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CONTENTS
1. A COMPREHENSIVE REVIEW O N RHIZOCTONIA SOLANI A
PATHOGENIC FUNGUS IMPACTING RICE PLANTS ...................... 1
2. BACULOVIRUSES AS INSECTICIDES IN INDIA: RECENT
ADVANCES AND FUTURE PROSPECTS ........................................... 15
3. PARASITIC ADAPTATION OF DIFFERENT PARASITES ............. 29
4. MODES OF DISSEMINATION OF DISEASE CAUSING PHYTO -
PARASITES ................................................................................................... 42
5. IMPACT AND CLASSIFICATIO N OF TRYPANOSOMA
PARASITES ................................................................................................... 59
6. IMPORTANCE OF SYMBIOTIC RELATIONSHIPS IN PLANTS . 70
7. COMPREHENSIVE INSIGHTS INTO LYMPHATIC FILARIAS IS:
GLOBAL IMPACT, ERADICATION INITIATIVES, AND
CHALLENGES AHEAD ............................................................................. 84
8. THE ORCHESTRA OF HELMINTHS: THE INTERPLAY OF
HELMINTH PARASITE S BETWEEN HUMANS AND
ANIMALS ..................................................................................................... 109
9. INFESTATION OF HELMINTH P ARASITES AND THEIR
EFFECT ON HUMAN BEING ................................................................. 151
10. PARASITIC DISEASES: IMPACT ON HEALTH OF FRESH
WATER EDIBLE FISH AND SOME DIAGNOSIS
APPROACHES ........................................................................................... 168
11. ALTERATION OF BEHAVIOUR DUE TO PARASITIC
INFESTATION ............................................................................................ 191
12. PARASITIC ADAPTATION OF FUNGI ASSOCIATED WITH
FLORAL AND FAUNA WITH THEIR ROLE IN ECOSYSTEM ... 204
1 | Parasitic Association
Chapter-1
A COMPREHENSIVE REVIEW ON RHIZOCTONIA
SOLANI A PATHOGENIC FUNGUS IMPACTING
RICE PLANTS
R. Marivignesh1*, Dr. M. I. Zahir Hussain1, Dr. M.
Sithijameela1, Dr. J. Shifa vanmathi1, Dr. P. S. Bensi1,
Chithaiya.P1, K. Ajintha1, G. Gayathri1, K. S. Uma Bharathi1,
Dr. M. Vijayalakshmi2
1. Department of Zoology, Sadakathullah Appa College
(Autonomous), Rahmath Nagar, Tirunelveli-627011 Affiliated to
Manonmaniam Sundaranar University, Tirunelveli, Tamilnadu,
India.
2. Department of Zoology, The M.D.T Hindu College, Tirunelveli-
10 Affiliated to Manonmaniam Sundaranar University,
Tirunelveli, Tamilnadu, India.
Abstract:
Rice (Oryza sativa) stands as a pivotal global staple, contributing
significantly to the sustenance of a substantial portion of the
world's population. However, the persistent threat posed by
Rhizoctonia solani, a formidable pathogenic fungus, continues to
challenge rice cultivation and productivity on a global scale. This
review endeavors to present a thorough examination of the
multifaceted interactions between Rhizoctonia solani and rice
plants, Rhizoctonia solani is a significant fungal pathogen known
for its detrimental effects on rice plants, causing considerable
economic losses in global rice production. This comprehensive
review synthesizes current knowledge on various aspects of
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Rhizoctonia solani, including its taxonomy, morphology, life
cycle, and the diverse mechanisms it employs to infect and
colonize rice plants. The review explores the factors influencing
the severity of Rhizoctonia solani-induced diseases, such as
environmental conditions, host susceptibility, and pathogen
variability. Additionally, the document examines the latest
advancements in molecular techniques and genomic studies that
contribute to a deeper understanding of the fungus and its
interactions with rice plants. Insights into disease management
strategies, including chemical, biological, and cultural control
measures, are discussed, highlighting the challenges and
opportunities in mitigating Rhizoctonia solani-associated damage
to rice crops. This review aims to provide a comprehensive
resource for researchers, agronomists, and policymakers working
towards sustainable solutions for managing Rhizoctonia solani and
safeguarding global rice production.
Key words: Rhizoctonia solani, Oryza sativa, Pathogens, Sheath
blight
Introduction
Rice (Oryza sativa) is not only a staple food but a cornerstone of
global sustenance, feeding a substantial portion of the world's
population. The leading contributors to global rice production are
currently China and India, with China holding the top position and
India following closely, collectively accounting for 51.4% of the
world's milled rice production (Seck et al., 2012). However, this
vital crop faces a persistent and formidable threat from Rhizoctonia
solani, a pathogenic fungus that poses significant challenges to rice
cultivation and productivity on a global scale. Rhizoctonia solani
Kühn, with its teleomorph identified as Thanatephorus cucumeris
Frank (Donk), is a necrotrophic soil-borne fungus. Initially
identified as a potato parasite by Kuhn in 1898, this fungus is
responsible for causing Rhizoctonia sheath blight (RSB)
(Almasia et al., 2008). Rhizoctonia solani has emerged as a major
concern due to its detrimental effects on rice plants, causing
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considerable economic losses in the realm of global rice
production. This review undertakes the crucial task of providing a
comprehensive examination of the intricate interactions between
Rhizoctonia solani and rice plants. Through a holistic approach, it
delves into various dimensions of this pathogenic fungus, spanning
its taxonomy, morphology, life cycle, and the diverse mechanisms
it employs to infect and colonize rice plants. The severity of
Rhizoctonia solani-induced diseases is influenced by a myriad of
factors explored within this review. From environmental
conditions to host susceptibility and pathogen variability,
understanding these determinants is pivotal for developing
effective strategies to mitigate the impact of this pathogen.
Moreover, the review sheds light on the latest advancements in
molecular techniques and genomic studies, which contribute
significantly to our understanding of Rhizoctonia solani and its
intricate interactions with rice plants. This exploration of cutting-
edge research enhances our capacity to unravel the complexities of
the fungus and opens avenues for targeted interventions. Disease
management strategies are a focal point of discussion in this
review, encompassing chemical, biological, and cultural control
measures. Through an examination of successes, limitations, and
ongoing challenges, the document aims to provide valuable
insights for researchers, agronomists, and policymakers. The
primary yearly hosts of the pathogen Rhizoctonia solani include
barley, pepper, wheat, tomatoes, beans, carrots, cloves,
cauliflower, chickpeas, potatoes, sugar beets, soybeans, tobacco,
rice, and more. Additionally, perennial host species of the pathogen
encompass fruit trees like pistachio and apricot, along with various
forest trees (Sneh et al., 1991; Bolton et al., 2010; Taheri and
Tarighi, 2011; Hane et al., 2014; Aydın and Ünal, 2021). The
ultimate goal is to pave the way for sustainable solutions that
effectively manage Rhizoctonia solani-associated damage to rice
crops, thereby safeguarding global rice production. This review, as
such, aspires to serve as a comprehensive resource for those
dedicated to advancing agricultural practices and ensuring the
resilience of one of the world's most critical food sources.
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Taxonomy of Rhizoctonia solani:
Rhizoctonia solani is a fungal pathogen belonging to the class
Basidiomycetes, order Cantharellales, and family
Ceratobasidiaceae. Within this family, it forms a distinct genus
called Rhizoctonia. The genus Rhizoctonia encompasses several
species, with Rhizoctonia solani being one of the most
economically significant and widely studied members.
Class: Basidiomycetes
Order: Cantharellales
Family: Ceratobasidiaceae
Genus: Rhizoctonia
Species: Rhizoctonia solani (Kühn J 1858)
Rhizoctonia solani is characterized by its septate, multinucleate
hyphae, and its reproductive structures are typically absent. The
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absence of a well-defined sexual reproductive stage contributes to
the challenges in its taxonomic classification. The classification of
Rhizoctonia solani is primarily based on cultural, morphological,
and molecular characteristics.
Morphology of Rhizoctonia solani:
1. Mycelium: Rhizoctonia solani exhibits a distinctive mycelial
structure. The mycelium is septate, meaning it is divided into
distinct cells by septa (cross-walls). The hyphae are multinucleate,
containing multiple nuclei within a single cell.
2. Sclerotia: One of the notable morphological features of
Rhizoctonia solani is the formation of sclerotia. Sclerotia are
compact masses of mycelium and serve as survival structures,
allowing the fungus to persist in the soil for extended periods. They
are often round or irregularly shaped and can vary in size.
3. Hyphal Anastomosis: Rhizoctonia solani is known for its
ability to undergo hyphal anastomosis, a process in which hyphae
from different individuals fuse. This feature plays a crucial role in
the formation of anastomosis groups, aiding in the identification
and classification of different strains.
4. Asexual Reproduction: Asexual reproduction in Rhizoctonia
solani occurs through the production of conidia, which are not as
commonly observed as in other fungi. The primary mode of
propagation is through mycelial growth and the formation of
sclerotia.
5. Lack of Sexual Reproduction: Unlike some fungi, Rhizoctonia
solani lacks a well-defined sexual reproductive stage. This
characteristic, along with its tendency for hyphal fusion and
anastomosis, contributes to the challenges in its taxonomy.
Understanding the taxonomy and morphology of Rhizoctonia
solani is crucial for accurate identification, classification, and
ultimately, the development of effective strategies for disease
management in various crops. Molecular techniques, including
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DNA sequencing, have become valuable tools in refining the
taxonomy of this complex fungal pathogen.
Life Cycle:
The life cycle of Rhizoctonia solani is characterized by its ability
to exist in different forms, including mycelium, sclerotia, and
anastomosis groups. The life cycle is primarily asexual, as the
fungus lacks a well-defined sexual reproductive stage. The
following outlines the key stages in the life cycle of Rhizoctonia
solani:
Disease cycle of Rhizoctonia solani
1. Survival Structures - Sclerotia:
o The life cycle often begins with the formation of survival
structures known as sclerotia. Sclerotia are dense masses of hyphal
tissue that serve as a reservoir of nutrients, allowing Rhizoctonia
solani to survive adverse environmental conditions such as drought
or extreme temperatures.
2. Germination of Sclerotia:
o When environmental conditions become favorable, sclerotia
germinate, giving rise to hyphae. The hyphae then spread out in
search of a suitable host or substrate.
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3. Mycelial Growth:
o The fungus primarily spreads through the growth of
mycelium. The mycelium is composed of septate, multinucleate
hyphae that can infect plants through various mechanisms.
4. Hyphal Anastomosis:
o A key feature of the Rhizoctonia solani life cycle is hyphal
anastomosis, where hyphae from different individuals come into
contact and fuse. This process leads to the formation of
anastomosis groups, which are essential for identifying different
strains of the fungus.
5. Infection and Colonization:
o Rhizoctonia solani infects plants through the mycelium. The
hyphae penetrate the plant tissues, causing various diseases
depending on the host plant and environmental conditions. The
fungus can infect different parts of the plant, including roots,
stems, and lower leaves.
6. Lesion Expansion and Sclerotium Formation:
o As the infection progresses, lesions may form on the infected
plant tissues. These lesions contribute to the further spread of the
fungus. Additionally, under certain conditions, Rhizoctonia solani
may form new sclerotia within infected plant tissues.
7. Release of Sclerotia:
o Sclerotia produced within infected tissues can be released into
the soil when infected plant material decomposes. These released
sclerotia can serve as a source of inoculum for future infections.
The life cycle of Rhizoctonia solani is completed when the fungus
produces new sclerotia, allowing it to survive in the soil during
unfavorable conditions. The absence of a clear sexual stage and the
predominance of asexual reproduction contribute to the
adaptability and persistence of Rhizoctonia solani in various
agricultural settings. Understanding this life cycle is crucial for
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developing effective disease management strategies, as the fungus
can cause significant economic losses in a variety of crops.
Disease Development:
Disease development caused by Rhizoctonia solani in rice plants is
multifaceted and can manifest in various forms, affecting different
parts of the plant. The severity and symptoms depend on factors
such as the strain of the pathogen, environmental conditions, and
the rice cultivar. Here's an overview of the typical disease
development process One of the common manifestations of
Rhizoctonia solani in rice plants is root rot. The fungus attacks the
roots, causing necrosis and decay. Infected roots may exhibit a
reddish-brown discoloration, and the overall root system can be
significantly compromised. Sheath blight is another major disease
caused by Rhizoctonia solani in rice. The fungus infects the sheaths
of rice plants, leading to the characteristic lesions that expand
along the leaf blades. Lesions often have a 'water-soaked'
appearance and may coalesce, resulting in extensive damage to the
foliage. Fungus can also infect the stems of rice plants, causing rot
and lesions. This can result in a weakening of the stem, leading to
lodging where the plant topples over especially during the later
stages of the rice plant's growth. Leaf spotting is a symptom where
small, dark lesions develop on the leaves of infected plants. These
spots may coalesce, leading to the formation of larger lesions and
compromising the overall photosynthetic capacity of the plant. In
young rice seedlings, Rhizoctonia solani can cause damping-off, a
condition where seedlings rot at the base of the stem, leading to
wilting and death. This can result in poor stand establishment and
reduced crop density. In Sclerotium Formation the disease
progresses, the fungus may produce sclerotia within infected
tissues. These survival structures serve as a means for Rhizoctonia
solani to persist in the soil, contributing to the pathogen's long-term
survival and potential for future infections.
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Factors Influencing Disease Severity:
Several factors influence the severity of diseases caused by
Rhizoctonia solani. Understanding these factors is crucial for
developing effective strategies to manage and mitigate the impact
of Rhizoctonia solani on crops. Here are key factors influencing
disease severity Environmental Conditions, Host Susceptibility,
Soil Conditions, Cultural Practices, Pathogen Variability,
Interactions with Other Pathogens, Fungicide Resistance, Plant
Growth Promoting Microorganisms (PGPM), by considering and
managing these factors, growers and researchers can develop
comprehensive strategies to minimize the severity of diseases
caused by Rhizoctonia solani and promote sustainable agriculture.
Advancements in Molecular Studies of Rhizoctonia solani
Advancements in molecular studies have significantly contributed
to our understanding of Rhizoctonia solani, providing valuable
insights into the pathogen's biology, genetic diversity, and
mechanisms of infection. Here are some key advancements in
molecular studies of Rhizoctonia solani:
1. Genomic Sequencing:
o The advent of high-throughput DNA sequencing technologies
has allowed researchers to sequence the entire genome of
Rhizoctonia solani. Genomic data provides a comprehensive view
of the pathogen's genetic makeup, including the identification of
genes associated with virulence, pathogenicity, and resistance to
fungicides.
2. Anastomosis Group Characterization:
o Molecular techniques have been instrumental in
characterizing different anastomosis groups (AGs) within
Rhizoctonia solani. Understanding the genetic diversity of the
pathogen helps researchers identify specific strains associated with
severe diseases and develop targeted management strategies.
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3. Identification of Pathogenicity Factors:
o Molecular studies have identified specific genes and proteins
in Rhizoctonia solani that play crucial roles in pathogenicity.
Understanding the mechanisms by which the fungus infects and
colonizes host plants allows for the development of targeted
interventions to disrupt these processes.
4. Gene Expression Profiling:
o Transcriptomic studies, which analyze the expression of genes
under different conditions, have provided insights into the dynamic
responses of Rhizoctonia solani during plant infection. This
information helps researchers understand how the pathogen adapts
to varying environments and host plants.
5. Molecular Markers for Strain Differentiation:
o Molecular markers, such as DNA-based markers and
microsatellites, have been developed for strain differentiation
within Rhizoctonia solani. These markers enable researchers to
distinguish between different strains and assess their distribution
and prevalence in agricultural settings.
6. Functional Genomics and Gene Editing:
o Functional genomics approaches, including gene knockout
and gene silencing techniques, have allowed researchers to
investigate the specific functions of genes associated with
pathogenicity. Gene editing technologies, such as CRISPR-Cas9,
offer the potential to modify the genome of Rhizoctonia solani for
research and disease control purposes.
7. Proteomic Studies:
o Proteomic analyses have been employed to identify and
characterize proteins produced by Rhizoctonia solani during
different stages of its life cycle. Proteomic studies contribute to a
better understanding of the molecular mechanisms involved in
infection and colonization.
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8. Metagenomic Approaches:
o Metagenomic studies analyze the genetic material recovered
directly from environmental samples, providing insights into the
diversity and dynamics of Rhizoctonia solani populations in soil
and plant tissues. This approach helps researchers understand the
factors influencing pathogen prevalence and distribution.
These molecular studies collectively enhance our understanding of
Rhizoctonia solani's biology, pathogenicity, and evolution. The
information gained from these advancements contributes to the
development of more precise and effective strategies for managing
diseases caused by Rhizoctonia solani in diverse agricultural
systems.
Disease Management Strategies:
Managing diseases caused by Rhizoctonia solani involves a
holistic approach that combines cultural, biological, and chemical
strategies. Given the complexity of the pathogen and its ability to
persist in diverse environments, an integrated management plan is
essential. Here are various disease management strategies for
Rhizoctonia solani, Implementing a crop rotation strategy with
non-host crops can help reduce the build-up of fungal in the soil.
This practice disrupts the pathogen's life cycle and minimizes the
risk of disease recurrence. Selecting and planting resistant cultivars
can be an effective strategy for managing fungal diseases. Resistant
varieties reduce the severity of infections and limit the impact on
crop yields. Breeding programs often focus on developing cultivars
with increased resistance to specific Rhizoctonia solani strains.
Maintaining appropriate spacing between plants can improve air
circulation and reduce humidity around the crop, creating an
environment less favorable for fungal development. Adequate
spacing also minimizes direct plant-to-plant contact, limiting the
spread of the pathogen. Ensuring proper soil drainage is crucial for
managing fungal diseases. Well-drained soils reduce the likelihood
of waterlogged conditions, which are conducive to the pathogen's
growth and spread. High nitrogen levels in the soil can promote
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lush plant growth, creating conditions favorable for fungus.
Balanced nutrient management, including avoiding excessive
nitrogen fertilization, helps maintain a healthy plant-soil system.
Beneficial microorganisms, such as certain bacteria and fungi, can
act as antagonists to Rhizoctonia solani. Application of biocontrol
agents, like Trichoderma spp and Mycorrhizal fungi, can help
suppress the pathogen and enhance plant resistance. Treating seeds
with fungicides or biological agents before planting can protect
seedlings from Rhizoctonia solani infections during the critical
early growth stages. This preventive measure helps establish a
healthy crop stand. Fungicides can be used as a part of an integrated
disease management strategy. However, it's important to note that
reliance solely on fungicides can lead to resistance development in
Rhizoctonia solani populations. Rotation of different fungicides
with distinct modes of action is recommended. Soil solarization
involves covering the soil with transparent plastic to raise soil
temperatures and reduce pathogen populations. Implementing
general good agricultural practices, such as proper sanitation,
removing crop debris, and avoiding the spread of contaminated
soil, can contribute to overall disease management and reduce the
risk of Rhizoctonia solani infections. Combining various disease
management strategies within an integrated pest management
framework ensures a comprehensive and sustainable approach to
controlling Rhizoctonia solani and mitigating its impact on crop
health. Diverse approaches are employed for managing diseases
induced by R. solani. These encompass chemical, physical, and
cultural measures, along with practices such as crop rotation, the
cultivation of resistant varieties, and the implementation of
biological control (Secor and Gudmestad, 1999; Bains et al., 2002;
Tsror, 2010). Implementing a combination of these strategies
tailored to the specific crop, environmental conditions, and local
context can help effectively manage diseases caused by
Rhizoctonia solani while promoting sustainable and resilient
agricultural systems.
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Conclusion:
In conclusion, this comprehensive review illuminates the intricate
dynamics between Rhizoctonia solani and rice plants. By delving
into the factors influencing disease severity, it becomes evident
that environmental conditions, host susceptibility, and pathogen
variability play pivotal roles in the pathogenicity of Rhizoctonia
solani. The advancements in molecular studies have opened new
frontiers, allowing for precise characterization, identification of
pathogenicity factors, and exploration of genetic diversity within
the fungus. The review underscores the importance of integrated
disease management strategies, ranging from cultural practices and
resistant cultivars to biological control and judicious fungicide use.
Recognizing the significance of crop rotation, optimal planting
density, and well-drained soils in mitigating Rhizoctonia solani's
impact, the implementation of these practices is crucial for
sustainable agriculture. As researchers, agronomists, and
policymakers navigate the complexities of Rhizoctonia solani, this
comprehensive resource aims to guide efforts toward informed
decision-making. By fostering collaboration and innovation, we
can develop strategies that not only manage the immediate threat
of Rhizoctonia solani but also contribute to the resilience and long-
term sustainability of global rice production.
References:
1. Almasia, N.I., A.A. Bazzini, H.E. Hopp and C. Vazquez-
Rovere. 2008. Overexpression of snakin-1 gene enhances
resistance to Rhizoctonia solani and Erwinia carotovora in
transgenic potato plants. Mol. Plant. Pathol., 9(3): 329-338.
2. Aydın, M.H., Ünal, F., 2021. Anastomosis groups and
pathogenicity of Rhizoctonia solani Kühn isolates isolated from
pistachio (Pistacia vera L.) saplings in Siirt province, Turkey.
Turkish Journal of Agricultural Research, 8(1): 18-26.
3. Bains, P.S., Bennypaul, H.S., Lynch, D.R., Kwachuk, L.M.,
Schaupmeyer, C.A., 2002. Rhizoctonia disease of potatoes
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(Rhizoctonia solani): Fungicidal efficacy and cultivar
susceptibility. Amererican Journal of Potato Research, 79(2): 99-
106.
4. Bolton, M.D., Panella, L., Campbell, L., Khan, M.F., 2010.
Temperature, moisture, and fungicide effects in managing
Rhizoctonia root and crown rot of sugar beet. Phytopathology,
100(7): 689-697.
5. Hane, J.K., Anderson, J.P., Williams, A.H., Sperschneider, J.,
Singh, K.B., 2014. Genome sequencing and comparative genomics
of the broad host-range pathogen Rhizoctonia solani AG8. PLoS
Genetics, 10(5): 1-16.
6. Kühn J., 1858. Die Krankenheiten der Kulturwachse, ihre
Ursachen und ihre Verhutung. Gustav Bosselman, Berlin, pp. 312.
7. Seck, P.A., A. Diagne, S. Mohanty and M.C.S.Wopereis.
2012. Crops that feed the world 7: Rice. Food Secur., 4(1): 7-
24. https://doi.org/10.1007/s12571-012-0168-1
8. Secor, G.A., Gudmestad, N.C., 1999. Managing fungal
diseases of potato. Canadian Journal Plant Pathology, 21(3): 213-
221.
9. Sneh, B., Burpee, L., Ogoshi, A., 1991. Identification of
Rhizoctonia Species. The American Phytopathological Society, St.
Paul, MN, USA.
10. Taheri, P., Tarighi, S., 2011. A survey on basal resistance and
riboflavin-induced defence responses of sugar beet against
Rhizoctonia solani. Journal of Plant Physiology, 168(10): 1114-
1122.
11. Tsror, L., 2010. Biology, epidemiology and management of
Rhizoctonia solani on potato. Journal of Phytopathology, 158(10):
649-658.
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Chapter-2
BACULOVIRUSES AS INSECTICIDES IN INDIA:
RECENT ADVANCES AND FUTURE PROSPECTS
Chithaiya. P1*, Dr. M. Sithijameela2*, Dr. M. I. Zahir Hussain2,
Dr. J. Shifa Vanmathi2, R. Marivignesh1, K. Ajintha1, G.
Gayathri1.
1. Research Scholar, Department of Zoology, Sadakathullah Appa
College (Autonomous), Rahmath Nagar, Tirunelveli-627011
Affiliated to Manonmaniam Sundaranar University, Tirunelveli,
Tamilnadu, India. E.mail: chithaiya.p@gmail.com Mob:
8807381865
2. Department of Zoology, Sadakathullah Appa College
(Autonomous), Rahmath Nagar, Tirunelveli-627011 Affiliated to
Manonmaniam Sundaranar University, Tirunelveli, Tamilnadu,
India.
Abstract
Insect pests pose significant threats to agricultural productivity
worldwide. Traditional insecticides have long been employed to
control these pests, but concerns regarding their harmful effects on
the environment and human health have paved the way for the
development of sustainable and targeted alternatives.
Baculoviruses, a group of insect-specific viruses, have emerged as
promising insecticides due to their high specificity, eco-
friendliness, and effectiveness in controlling various pest
populations. This research article provides an overview of recent
advances in utilizing baculoviruses as insecticides in India,
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discussing their potential benefits, challenges, and future
prospects.
Key words: Baculoviruses, Insecticides in India, Future Prospects.
Introduction
In the pursuit of sustainable and eco-friendly solutions to address
the pressing challenges of agricultural pest management, the
utilization of biological control agents has gained prominence.
Among these agents, baculoviruses have emerged as promising
biopesticides, offering targeted and species-specific control of
insect pests. In the context of Indian agriculture, where the reliance
on chemical insecticides has raised concerns about environmental
sustainability and the development of resistance, the exploration of
alternative strategies becomes imperative. This research article
delves into the recent advances in utilizing baculoviruses as
insecticides in India, shedding light on their unique characteristics,
modes of action, applications, challenges faced, and the promising
future prospects they hold for the agricultural landscape. The
escalating global demand for food production necessitates
effective pest management strategies that not only mitigate crop
losses but also align with the principles of sustainable agriculture.
Baculoviruses, belonging to the family Baculoviridae, present an
intriguing avenue for achieving these dual objectives. Their
specificity to certain insect species, coupled with their safety for
non-target organisms, makes them an attractive alternative to
conventional chemical insecticides.
As India stands at the forefront of the global agricultural landscape,
grappling with diverse climatic conditions and a myriad of crop-
specific pests, the need for innovative and sustainable pest
management practices becomes particularly pronounced (Fuxa
et.al, 2017). This article seeks to provide a comprehensive
overview of the recent advancements in the use of baculoviruses as
insecticides in the Indian context, emphasizing their potential
contribution to integrated pest management (IPM) and the
evolution of a more sustainable agricultural paradigm. The
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exploration of baculoviruses as insecticides in India involves a
multifaceted examination of their biological characteristics, modes
of infection, and recent breakthroughs in research and application.
Furthermore, this article will address the practical challenges faced
in deploying baculoviruses in the field, exploring potential
solutions and strategies for optimization. By examining the current
state of baculovirus research in the Indian agricultural context, we
aim to pave the way for a deeper understanding of their role,
challenges, and the promising future they hold as a cornerstone in
the sustainable management of insect pests in Indian agriculture.
Baculoviruses: Overview and Classification
Baculoviruses are a unique and fascinating group of insect viruses
known for their specificity in infecting insects, particularly
members of the order Lepidoptera. These viruses have garnered
significant attention due to their potential as biopesticides and their
intriguing life cycle, which involves distinct phases for
transmission and systemic infection. This section provides an
elaborate exploration of the overview and classification of
baculoviruses, shedding light on their biological characteristics,
classification criteria, and relevance in the context of insect pest
management.
1. Biological Characteristics:
Baculoviruses belong to the family Baculoviridae and are
characterized by large, enveloped, double-stranded DNA genomes.
The name "baculovirus" is derived from the characteristic rod-
shaped appearance of their virions. These viruses exhibit a unique
biphasic life cycle, consisting of the occlusion bodies (OBs) and
the budded virus (BV). The OBs serve as the primary means of
transmission, providing a protective matrix for the virus to persist
in the environment, while the BV facilitates systemic infection
within the host insect.
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2. Classification Criteria:
Baculoviruses are primarily classified based on the type of insect
hosts they infect, and the two major genera are
nucleopolyhedroviruses (NPVs) and granuloviruses (GVs).
a. Nucleopolyhedroviruses (NPVs):
NPVs infect larvae of lepidopteran insects. These viruses cause the
formation of polyhedra, which are inclusion bodies containing
numerous occlusion bodies (OBs). The polyhedra protect the virus
particles and facilitate their transmission to other susceptible hosts.
b. Granuloviruses (GVs):
GVs infect a broader range of lepidopteran insects, including both
larvae and pupae. Unlike NPVs, GVs form single-nucleocapsid
granules instead of polyhedra. The granules are embedded in the
host's epithelial cells and are released upon the death of the host,
contributing to the horizontal transmission of the virus.
3. Host Specificity:
One of the remarkable features of baculoviruses is their host
specificity. Each baculovirus strain tends to infect a limited range
of insect species, and sometimes even specific developmental
stages of those species. This specificity is advantageous in the
context of biological pest control as it minimizes the impact on
non-target organisms, making baculoviruses an environmentally
friendly alternative to chemical insecticides.
4. Significance in Insect Pest Management:
The specificity of baculoviruses, coupled with their safety for non-
target organisms, positions them as valuable tools in integrated pest
management (IPM) strategies. These viruses have demonstrated
efficacy against a variety of agricultural pests, such as the cotton
bollworm (Helicoverpa armigera) and the armyworm (Spodoptera
spp.). Their potential to contribute to sustainable agriculture by
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reducing reliance on chemical pesticides makes them a subject of
intensive research and development.
5. Modes of Action of Baculoviruses:
Baculoviruses, a group of insect-specific viruses, exert their
pathogenic effects through a series of well-coordinated and highly
specific interactions with their insect hosts. Understanding the
modes of action of baculoviruses is essential for harnessing their
potential as biopesticides and integrated pest management (IPM)
tools. This section provides a comprehensive exploration of the
mechanisms through which baculoviruses infect and manipulate
their hosts, leading to insect mortality.
6. Oral Infection and Midgut Epithelium Invasion:
Baculoviruses initiate infection through the oral route, as insects
typically ingest occlusion bodies (OBs) containing viral particles.
The alkaline environment of the insect midgut triggers the
dissolution of the occlusion bodies, releasing occlusion-derived
virus (ODV) particles. ODV particles attach to and enter midgut
epithelial cells through interactions with specific cell surface
receptors.
7. Primary Replication in Midgut Cells:
Once inside midgut cells, the viral genome is released, and
transcription and replication processes commence. The infected
midgut cells become the primary site for viral replication, resulting
in the formation of large virus-induced inclusion bodies.
8. Secondary Dissemination - Systemic Infection:
As infection progresses, a second type of virus, known as budded
virus (BV), is produced in large quantities within the midgut cells.
BVs spread to various tissues and organs, initiating a systemic
infection. The virus hijacks host cellular machinery to replicate,
leading to the destruction of multiple tissues throughout the insect
body.
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9. Lethal Impact on Host:
Baculoviruses induce physiological and biochemical changes in
infected insects, disrupting essential processes and causing
systemic failure. The orchestrated destruction of host tissues
culminates in the death of the infected insect. The host's cadaver
becomes a source of virus transmission, as occlusion bodies form
within infected tissues, protecting the viral particles until
consumed by other susceptible hosts.
10. Host-Specificity and Non-Target Safety:
Baculoviruses exhibit a high degree of host specificity, infecting a
limited range of insect species and developmental stages. This
specificity contributes to their safety for non-target organisms, an
important characteristic for environmentally sustainable pest
control strategies. Understanding the intricacies of baculovirus
infection is crucial for optimizing their use as biopesticides. The
specificity of baculoviruses to certain insect hosts minimizes the
impact on beneficial insects and other non-target organisms,
making them an attractive option for integrated pest management
programs. Additionally, the evolution of novel delivery methods,
such as formulations for field application, enhances the practicality
and efficacy of baculovirus-based insecticides. Ongoing research
continues to unveil the molecular details of baculovirus-host
interactions, providing insights that may lead to the development
of more potent and targeted pest control solutions.
Recent Advances in Baculovirus Research in India
Baculoviruses have emerged as promising candidates for
sustainable pest management in agriculture, and India has been
actively engaged in advancing research to harness the full potential
of these viruses. The following notes highlight some of the recent
advances in baculovirus research in the Indian context, focusing on
isolation, characterization, production optimization, and the
development of genetically modified strains (Ali et.al, 2020).
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1. Isolation and Characterization: Indian researchers have
made significant strides in isolating indigenous strains of
baculoviruses from diverse ecological niches. Characterization
studies involve genomic analyses, determining host specificity,
and understanding the biological and physiological features of
isolated strains.
2. Optimization of Production Methods: Efforts have been
directed towards optimizing the production of baculoviruses to
ensure scalability and cost-effectiveness. Researchers are
exploring various production systems, including insect cell culture
and biofermentation, with a focus on maximizing viral yield and
purity.
3. Genetic Modification for Enhanced Performance: Genetic
engineering techniques have been employed to modify baculovirus
strains for improved performance as insecticides. This includes
enhancing the speed of kill, expanding the range of susceptible
hosts, and increasing resistance to environmental factors.
4. Field Trials and Efficacy Studies: Field trials have been
conducted to assess the efficacy of baculovirus-based insecticides
under real-world conditions. Studies have focused on key
agricultural pests in India, such as the cotton bollworm
(Helicoverpa armigera) and the tobacco caterpillar (Spodoptera
litura).
5. Formulation Development: Researchers are working on
developing effective formulations for the field application of
baculovirus-based insecticides. Formulation studies aim to
enhance the stability, shelf life, and ease of application of
baculovirus products.
6. Exploration of Novel Delivery Systems: Novel delivery
systems are being explored to improve the precision and efficiency
of baculovirus application. This includes the development of
biopesticide formulations, such as sprays and granules, that
enhance the targeted delivery of baculoviruses to pest populations.
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7. Integration into Integrated Pest Management (IPM)
Strategies: Baculoviruses are being integrated into broader IPM
strategies in Indian agriculture. The goal is to develop holistic pest
management approaches that combine the strengths of
baculoviruses with other compatible control methods, reducing
reliance on chemical pesticides.
8. Collaboration and Knowledge Sharing: Collaboration
between research institutions, agricultural universities, and
industry partners has been instrumental in advancing baculovirus
research in India. Knowledge sharing and collaborative efforts
contribute to a more comprehensive understanding of baculovirus
biology and their practical applications in pest management.
Baculoviruses Applications in Agriculture
Baculoviruses, owing to their specificity and environmentally
friendly nature, have found diverse applications in agriculture for
pest control. These applications span various crops and target a
wide range of insect pests. The following notes elaborate on the
key aspects of the applications of baculoviruses in agriculture.
Targeted Pest Control: Baculoviruses are highly specific in their
host range, providing targeted control of specific insect pests
without affecting beneficial organisms. This specificity is
advantageous in preserving natural predators and pollinators in
agroecosystems. Key Target Pests: Baculoviruses have shown
efficacy against economically significant pests such as the cotton
bollworm (Helicoverpa armigera), corn earworm (Helicoverpa
zea), cabbage looper (Trichoplusia ni), and the armyworm
(Spodoptera spp.). The ability to target these pests addresses
critical challenges in major crops like cotton, corn, and vegetables.
Cotton Agriculture: In cotton agriculture, where bollworms pose a
severe threat, baculoviruses have been employed to manage
populations effectively. Baculovirus-based formulations have been
developed for application during key pest developmental stages.
Maize (Corn) Protection: Baculoviruses have demonstrated
success in controlling pests in maize crops, contributing to reduced
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reliance on chemical insecticides. Their application aligns with
sustainable agriculture practices and reduces the environmental
impact associated with conventional pesticides. Vegetable Crops:
Baculoviruses are applied in vegetable crops to combat pests like
the cabbage looper and diamondback moth (Plutella xylostella).
These applications contribute to the promotion of integrated pest
management strategies in vegetable cultivation. Rice Agriculture:
In rice fields, where stem borers and leaf folders are common pests,
baculoviruses have been explored for their potential in controlling
these insects. Research is ongoing to optimize application methods
for efficient pest suppression in rice crops. Application Methods:
Baculoviruses can be applied using various methods, including
foliar sprays, granule formulations, and seed coatings. These
methods allow for flexibility in adapting baculovirus applications
to different crop types and pest management strategies.
Compatibility with Biological Control: Baculoviruses are
compatible with other biological control agents, allowing for
integrated pest management approaches. This compatibility
supports the development of holistic strategies that combine the
strengths of various biocontrol methods. Residue-Free Produce:
The use of baculoviruses in agriculture contributes to the
production of residue-free or low-residue crops. This aligns with
consumer demand for safe and environmentally sustainable food
products (Loyola et.al, 2021).
Challenges in the Use of Baculoviruses as Biopesticides
While baculoviruses offer significant potential as biopesticides,
their practical application in agriculture faces several challenges
that need to be addressed for wider adoption and efficacy. The
following notes delve into some of the key challenges associated
with the use of baculoviruses, including the need for improved
formulations, optimizing production scalability, and addressing
factors influencing their persistence in the field. Formulation
Challenges: Baculoviruses, being sensitive biological entities, face
challenges related to formulation for field application.
Formulations must ensure the stability and viability of the virus,
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especially under variable environmental conditions. Stability and
UV Sensitivity: Baculoviruses are sensitive to ultraviolet (UV)
radiation, which can reduce their efficacy in the field. Formulations
need to incorporate stabilizers or protective agents to enhance
resistance to UV degradation. Persistence in the Field:
Baculoviruses often exhibit limited persistence in the field,
necessitating frequent reapplication. Enhancing their persistence is
crucial for sustained pest control and reducing the frequency of
application. Optimizing Application Timing: The effectiveness of
baculoviruses is influenced by the timing of their application
concerning the pest life cycle. Optimizing the timing of application
is critical for achieving maximum impact on pest populations.
Scalability of Production: While baculovirus production methods
have improved, scalability remains a challenge for large-scale
agricultural use. Developing cost-effective and scalable production
processes is essential for commercial viability. Cost
Considerations: The production and formulation of baculovirus-
based biopesticides can be cost-intensive. Reducing production
costs and making these biopesticides economically competitive
with chemical alternatives is a significant challenge. Host Range
Limitations: Baculoviruses exhibit specificity towards certain
insect hosts, limiting their applicability against a broader spectrum
of pests. Expanding their host range or developing multiple strains
for different pests is a challenge in achieving comprehensive pest
control. Resistance Management: Pests can develop resistance to
baculoviruses over time, similar to chemical insecticides.
Implementing effective resistance management strategies is
essential to prolong the utility of baculovirus-based biopesticides.
Environmental Persistence: Environmental factors such as
temperature and humidity can impact the persistence of
baculoviruses. Understanding and addressing these factors are
crucial for predicting and optimizing their field performance.
Regulatory Approval: Obtaining regulatory approvals for
baculovirus-based products can be a complex and time-consuming
process. Complying with regulatory standards and ensuring
product safety are critical for market acceptance. Public
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Perception: Public perception and awareness of biopesticides,
including baculoviruses, may influence their acceptance.
Education and outreach efforts are needed to inform farmers and
consumers about the benefits and safety of these biopesticides
(Gurule et.al, 2020).
Future Prospects of Baculoviruses as Insecticides in India
Baculoviruses, with their specificity and eco-friendly nature, hold
immense promise as insecticides in the agricultural landscape of
India. Ongoing research and recent advancements provide a
glimpse into the future prospects of baculoviruses in pest
management. The following notes highlight key areas of
development and the potential trajectory of baculovirus
applications in India (Pathak et.al, 2018).
1. Enhanced Formulations for Field Application: Future
research is likely to focus on developing advanced formulations
that improve the stability and persistence of baculoviruses in the
field. Incorporation of innovative delivery systems, such as
microencapsulation or nanotechnology-based formulations, can
enhance targeted delivery and protection against environmental
factors.
2. Optimized Production Methods: Scalability and cost-
effectiveness of baculovirus production are crucial for large-scale
agricultural use. Continued research will aim at refining and
optimizing production methods, exploring alternative hosts for
virus propagation, and identifying cost-effective media for mass
production.
3. Genetic Modification for Improved Performance: Genetic
engineering holds potential for developing strains of baculoviruses
with enhanced insecticidal properties. Future research may focus
on modifying viral genomes to improve speed of kill, broaden the
host range, and increase resistance to environmental stressors.
4. Expansion of Host Range: Research efforts may seek to
expand the host range of baculoviruses to target a broader spectrum
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of insect pests. Identifying and characterizing new strains that are
effective against key pests in various crops can contribute to the
versatility of baculovirus-based insecticides.
5. Integrated Pest Management (IPM) Strategies: The future
deployment of baculoviruses is likely to involve integration into
holistic IPM strategies. Combining the use of baculoviruses with
other biopesticides, cultural practices, and natural enemies can
enhance the overall effectiveness of pest management.
6. Climate-Adapted Strains: Given the diverse climatic
conditions in India, research may focus on developing climate-
adapted strains of baculoviruses. Strains that perform optimally in
varying temperature and humidity conditions can ensure year-
round efficacy in different regions.
7. Commercialization and Market Acceptance: As research
progresses, commercialization of baculovirus-based products will
play a crucial role in their widespread adoption. Effective
marketing strategies, farmer education, and collaborations with
agribusinesses will contribute to market acceptance.
8. Sustainable Agriculture Advocacy: Future prospects
involve positioning baculoviruses as central to sustainable
agriculture practices. Advocacy efforts may emphasize the
environmental benefits, reduced chemical residues, and overall
sustainability of baculovirus-based pest management.
Conclusion:
The exploration of baculoviruses as insecticides in India has
witnessed significant strides in recent years, marked by noteworthy
advancements in research and a burgeoning recognition of their
potential in sustainable agriculture. The elucidation of their unique
modes of action, coupled with the development of novel
formulations and genetic modifications, underscores the
transformative impact these viruses could have on pest
management practices. As we delve into the conclusion of this
exploration into "Baculoviruses as Insecticides in India: Recent
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Advances and Future Prospects," it becomes evident that these
biopesticides hold promise as a key component of integrated pest
management strategies, contributing to the evolution of a more
sustainable and environmentally conscious approach to
agriculture. The recent advances in isolating and characterizing
indigenous baculovirus strains in India, as highlighted in the work
of Kumar et al. (2022), signify a crucial step towards tailoring
solutions to the unique pest challenges faced by the country.
Understanding the local viral diversity becomes paramount for the
successful implementation of baculovirus-based insecticides,
ensuring their compatibility with the diverse agroecosystems
prevalent in India.
The challenges faced by baculoviruses, such as the need for
improved formulations, scalability optimization, and enhanced
field persistence, provide a roadmap for future research endeavors.
Collaborative efforts between research institutions, industry
stakeholders, and regulatory bodies will be instrumental in
addressing these challenges and unlocking the full potential of
baculoviruses in Indian agriculture.
The future prospects of baculoviruses as insecticides in India are
underscored by the anticipated refinement of production methods,
development of genetically modified strains for improved
performance, and the expansion of their host range to target a
broader spectrum of pests. As these advancements unfold, the
integration of baculoviruses into holistic integrated pest
management strategies is expected to gain momentum, fostering a
balanced and sustainable approach to pest control. Furthermore,
the commercialization and market acceptance of baculovirus-
based products will play a pivotal role in shaping their impact on
Indian agriculture. Advocacy efforts emphasizing the
environmental benefits, reduced chemical residues, and overall
sustainability of baculovirus-based pest management will be
crucial in garnering support from farmers and stakeholders alike.
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In conclusion, the recent advances in baculovirus research in India
signify a paradigm shift towards sustainable and environmentally
friendly pest management practices. As we navigate the
complexities of modern agriculture, the integration of innovative
solutions, such as baculoviruses, offers a beacon of hope for a more
resilient and ecologically conscious future in Indian agriculture.
The journey has just begun, and the continued collaboration
between researchers, policymakers, and the agricultural
community is essential to realizing the full potential of
baculoviruses as insecticides in the agrarian tapestry of India.
Reference:
1. Gurule, S., & Nayak, S. (2020). Baculovirus as a Promising
Biopesticide for Insect Pest Management. Advances in
Biotechnology, 19(1), 33-41.
2. Ali, S. S., & Xiang, J. M. (2020). Baculoviruses: Biopesticides
from the Nature. In Advances in Biopesticide Research and
Application (pp. 83-103). Springer.
3. Loyola, M. F. A., Jr., Tang, S., Nontakhot, J., &
Tuntawongwuriyaporn, S. (2021). Development of Baculovirus-
based Biopesticides for Insect Pest Management in Asia. In
Advances in Biopesticide Research and Application (pp. 149-173).
Springer.
4. Pathak, A. K., & Mishra, A. K. (2018). Baculovirus mediated
insect pest management: A review of current research and future
directions. 3 Biotech, 8(3), 138.
5. Fuxa, J. R., & Richter, A. R. (2017). Baculovirus insecticides
in pest management in India. In Advances in Insect Pest
Management Techniques (pp. 145-170). Springer.
6. R. Kumar et al., "Isolation, identification, and characterization
of Baculovirus isolates from India," Archives of Virology, 2022.
[DOI: 10.1007/s00705-022-05354-7]
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Chapter-3
PARASITIC ADAPTATION OF DIFFERENT PARASITES
DR. SHASHI KANT LABH
Assistant Professor
(Guest Faculty)
Department of Zoology, K.M.D.College Parbatta, Khagaria
Munger University Munger. Bihar
E-mail Id – labhshashi@gmail.com
ABSTRACT
A parasite is an organism which lives in or on another organism
called host and benefits by deriving shelter and nutrients from
them. All types of parasites show peculiar adaptations to survive in
or on the host system and to maximum benefit from them. Parasites
show three level adaptations; these are Structural Adaptations
(Morphological and Anatomical Adaptations), Physiological
Adaptation and Reproductive Adaptation. Parasites that live in, on
or with another organism (host). They feed, grow or multiply in a
way that harms their host. However, they need their host for their
survival. For this reason, they rarely kill their host, but they often
carry diseases that can be life-threatening. The host is an organism
which supports the parasite. The association between two different
organisms wherein one benefits at the expense of the other is called
parasitism. Man and other living things on earth live in an
entangling relationship with each other. They don’t exist in an
isolated fashion. They are interdependent; each forms a strand in
the web of life. Structural and functional modification of a
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parasite to live successfully in its specific habitat or
environment is known as parasitic adaptations.
KEYWORDS: Parasite, Host, Parasitism, Adaptation,
Disease.
INTRODUCTION
A parasite is an organism which lives in or on another organism
called host and benefits by deriving shelter and nutrients from
them. All types of parasites show peculiar adaptations to survive in
or on the host system and to maximum benefit from them. Parasites
show three level adaptations, these are Structural Adaptations
(Morphological and Anatomical Adaptations), Physiological
Adaptation and Reproductive Adaptation. Parasites that live in, on
or with another organism (host). They feed, grow or multiply in a
way that harms their host. However, they need their host for their
survival. For this reason, they rarely kill their host, but they often
carry diseases that can be life-threatening. The host is an organism
which supports the parasite. The association between two different
organisms wherein one benefits at the expense of the other is called
parasitism. The survival of the parasite in the body of the host
depends upon its ability to adapt to the surrounding environment at
the side of its infection, this is called microenvironment. To
adapt to this microenvironment, certain morphological, anatomical
and physiological changes occur and because of which the parasite
survive in the host. Such changes which facilitate a parasite to
adapt to parasitic mode of in the host itself are called parasitic
adaptation. In order to lead a parasitic mode of life complete or
partial degeneration or loss of organs has taken place in the body
of parasites.
DIFFERENT TYPES OF PARASITES
Ectoparasites: - A parasitic organism that lives on the outer
surface of its host is called ectoparasite, e.g. lice, ticks, mites etc.
Endoparasites: - Aparasites that live inside the body of
their host is called endoparasite, e.g. Entamoeba histolytica.
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Obligate Parasite: - A parasite that cannot complete its life
cycle without exploiting a suitable host is called obligate parasite,
e.g. Plasmodium spp.
Faculative Parasites: - An organism that exhibits both
parasitic and non-parasitic modes of living and hence does not
absolutely depend on the parasitic way of life, but is capable of
adapting to it if placed on a host. E.g. Naegleria fowleri.
Accidental Parasites: - When a parasite attacks an unnatural
host and survives. E.g. Hymenolepis diminuta (rat tapeworm).
DIFFERENTS TYPES OF HOST
Definite host: - A host that harbors a parasite in the adult
stage or where the parasite undergoes a sexual method of
reproduction. Example: Dog for Ancylostoma canium, Cattle for
fasciola gigantica.
Intermediate host: - It is the host which harbour the immature
stage of the parasite. In some cases, larval development is
completed in two different intermediate hosts, referred to as first
and second intermediate hosts.
Reservoir host: - A host that makes the parasite available for
the transmission to another host and is usually not affected by the
infection.
Natural host: - A host that is naturally infected with certain
species of parasite.
Accidental host:-A host that is under normal circumstances
not infected with the parasite.
PARASITIC ADAPTATION
Structural and functional modification of a parasite to live
successfully in its specific habitat or environment is known as
parasitic adaptations. Parasitic group of Helminthes are
modified morphologically, physiologically and anatomically to
live in particular environment.
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PARASITIC ADAPTATION OF FASCIOLA HEPATICA
Fasciola hepatica, commonly known as liver fluke is an
endoparasite of sheep which resides in the liver and duct. It is
worldwide distributed. It causes liver rot disease in sheep.
Systematic position
Kingdom – Animalia, Phylum – Platyhelminthes, Class –
Trematoda, Order – Digenea ,Genus – Fasciola, Species –
hepatica
Fig.1: Fasciola hepatica
1. Body wall with thick cuticle: - Cuticle serves the function
of protection as it is tough, resistant to the digestive juices of
the host. Spinules anchor the fluke in the bile passage.
2. Presence of oral and ventral suckers: - The suckers of
Fasciola help in the attachments with the host by vacuum.
Especially ventral sucker are more modified for this function.
3. Locomotory organs are absent: - Due to endoparasitic
nature there is no need of locomotion for food.
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4. Simple external organisation: - Due to endoparasitic mode
the appendages are absent and there is no distinction of head,
trunk and tail. Body is flat.
5. Respiration: - Respiration is anaerobic type due to absence
of oxygen.
6. Digestive system: - Digestive system modified to its
parasitic mode of life. Mouth is surrounded by oral sucker.
Pharynx is highly muscular and sucking in nature. Intestinal
caeca are present which provide to store more and more food.
Digestive glands are absent as the parasite feeds upon ready
food material.
7.Nervous system:- Nervous system poorly developed as the
parasite lives inside the body of the host so external
environmental influence is nil and internal changes are least.
Specialised sense organs are absent.
8. Reproductive organs: - Reproductive organs are well
developed. The life of parasite in uncertain and it totally
depend upon the host. Well-developed reproductive organs
produce gametes in huge number and bisexual provides the
chance of self-fertilization in absence of second host.
PARASITIC ADAPTATION OF TAENIA SOLIUM
Taenia solium is an endoparasite of man which is found in the
intestine. It attaches to the mucosa with the help of scolex and
rest tapering body lies freely in the intestine. It is commonly
found in the tropical region where nearly cooked pork is
utilized. It is dorsoventrally flattened like a ribbon which is
long, narrow and possesses numerous segments.
Systematic position
Kingdom – Animalia, Phylum – Platyhelminthes, Class –
Cestoda, Order – Taenoidea, Genus – Taenia, Species – solium
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Fig.2: Taenia solium
1. Body: - Body is dorsoventrally flattened ribbon like which
helps in floating.
2. Neck: - Neck region develops new segments throughout the
life of increase length and cover up the loss of riped proglotids.
3. Presence of thick cuticle: - The cuticle serves the protective
function against the digestive juices.
4. Appendages: - Appendages are absent as due to parasitic
mode of life here is no need of appendages.
5. Presence of Scoles: - It is adhesive organs having four cup
like sectorial suckers. A prominent conical rostellum with
double circle of chitinous hooks is present. Scolex helps in
attachment and burring in the intestinal mucosa.
6. Absence of alimentary canal: - The pre-digested food of
the host is absorbed directly by the general body surface so
there is no need of alimentary canal and digestive glands.
7.Production of antienzymes: - The adult passes whole life in
the intestine. Antienzyme sectetion protect it against the action
of all digestive juices. In absence of antienzyme formation
worms die.
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8. Respiration: - Anaerobic type of respiration is found due to
lack of abundant oxygen.
9. Sense organs: - Movement is limited so there is no sense
organs are present.
10. Reproductive organs: - Reproductive organs are well
developed due to uncertainty of the life. It may produce more
new forms in shot time. In Tania compete set of reproductive
organs is present in each proglotid. It may produce 500000 –
700000 eggs daily.
PARASITIC ADAPTATION OF ASCARIS
LUMBRICOIDES
Ascaris lumbricoids is an endoparasite which resides in the
intestine of man. It is worldwide in distribution. The number
of worms may be 500 or more in a single host.
Systematic position, Kingdom – Animalia, Phylum –
Aschelminthes, Class – Nematoda, Order – Ascaoidea, Genus
– Ascaris, Species – lumbricoids
Fig.3: Ascaris lumbricoids
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1. Cuticle: - Cuticle is thick, tough and made up of several
layers. It protects the body against the digestive juice of the
intestine of host.
2. Alimentary canal: - Pharynx is muscular and modified for
sucking the food.
3. Digestive gland: - Digestive glands are generally absent as
it receives the digested food from the host intestine.
4. Respiration: - Anaerobic type of respiration is take place.
5. Resparatory organs: - Respiratory organs are absent in
ascaris lumbricoides.
6. Nervous system: - Nervous system is poorly developed.
7. Reproductive organs: - Reproductive organs are highly
developed. The female is capable to produce about 20000 eggs
daily. Eggs may remain unchanged up to long time due to
presence of well protective egg shell.
PARASITIC ADAPTATION OF HIRUDINARIA
GRANULOSA
(The common Indian Cattle Leech)
The common Indian cattle leech, Hirudinaria granulos found
in freshwater tanks, ponds, lakes, swamps and slow streams. It
prefers shallow water and remains concealed under weeds, logs
and stones. It is sanguivorous (blood sucking). It sucks the
blood of fishes, frogs and also cattle or human beings when
they enter the pond. Leeches show great diversity in their
habits and habitat. Some species are marine and some are fresh
water while others are terrestrial.
Systematic position: Kingdom – Animalia, Phylum –
Annelida, Class – Hirudinea, Order – Gnathobdellida, Genus –
Hirudinaria, Species – granulosa
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Fig.4: External morphology of Leech (A. Dorsal view
B.Ventral view)
The hirudinaria granulosa lead a semiparasitic life as they are
sanguivorous. They exhibit several modification of parasitic
life in habits, habitat, external features, digestive system, sense
organs and mode of reproduction.
Adaptation in Habit and Habitat
The Hirudinaria is found in fresh water ponds, ditches tanks
slow running streams etc. which are frequently visited by men
and cattle. The leeches prefer shallow waters where they can
hide themselves under stones, logs and weeds to getting
maximum protection from enemies. The leeches are very active
swimmers and this proves good changes for searching the host
and escaping the enemies.
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Adaptation in External Morphology:
The external morphology of the Hirudenaria exhibits the
following ectoparasitic adaptation:
Shape: - The body is long and flat without any locomotory
organs. Due to absence of locomotory organs the host remains
unaware of the parasite.
Slimy body: - The body of the animal is slimy due to the
presence of slime gland in the body wall.
Sucker: - The animal is provided with adhesive suckers at both
the ends which help in clinging and also in locomotion. The
sucker provides firm adhesion at the time of feeding on the
host.
Jaws: - In leech the mouth is surrounded by three jaws which
are chitinous, curved and are provided with teeth on free edges.
The saw like movement of the jaw inflict a painless tri – radiate
wound on the skin of the host through which the blood oozes
out continuously.
Adaptation in Digestive System:-The digestive system is well
modified with the ectoparasitic life for ingestion, storage and
digestion of the food.
Suctorial apparatus: - The buccal cavity and the pharynx
form a sectorial apparatus which acts as a sectorial pump. The
pharynx is highly muscular and is provided with radiating
muscles for quick alternate expansion and contraction of the
pharyngeal cavity.
Hirudin:- Hirudin is secreted in the salivary glands which acts
as anticoagulant and prevent the clotting of blood. It ensures
the continuous supply of the blood. The hirudin is put on the
oozing blood at the wound though openings situated on the
salivary papillae of the jaws.
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Storing devices: - In leech the chances of getting the host for
food are rare and much depends upon chance. Sometimes the
animal has to live for months without food. So there are
modifications in the alimentary canal to store the food. The
crop is spacious, long elastic and capable of great dilation. It
is further provided with lateral diverticulae or storing pockets.
With this modification the leech stores blood and live without
food even for more than a year.
Fig.05: Alimentary Canal of Leech
Slow digestion: - The last chamber of the crop opens into the
stomach through a small aperture guarded by sphincter. The
blood passes into the stomach very slowly and drop by drop.
The digestion is very slow and complete digestion of the blood
may take several months. Due to slow digestion the active
digestive enzymes are lacking in the leeches.
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Sense Organs Adaptation:- The sense organs e.g, eyes,
annular receptors and the segmental receptors are well
developed which provide good opportunities to the animal for
semi-parasitic life.
Reproduction Adaptation
The animal is hermaphrodite which is advantageous for
parasitic life as both the individuals reproduce after copulation.
The formation of the cocoon is also advantageous as it serves
as protective chamber for the developing embryos. The cocoon
contains 1-14 embryos. The development is very quick and is
completed within 15days to ensure and maintain a regular
population.
CONCLUSION
Parasitic group of Helminthes are modified morphologically,
physiologically and anatomically to live in particular
environment. All types of parasites show peculiar adaptations to
survive in or on the host system and get maximum benefit
Parasitic group of Helminthes and nematodes are modified
morphologically, physiologically and anatomically to live in
particular environment. Ascaris lumbricoids is an nematodes
parasite in the small intestine of children and adult human
beings. Ascaris in narrow, cylindrical and vermiform. The size
of female is larger than the male.
REFERENCES
1. Belding,D, Textbook of clinical parasitology,2nd edition New
York,1952
2. Brown, H.W. and Neva. F.A. Basic clinical Parasitology (5th
edn) New York: 1982.
3. Viney, M. E. (1996). Developmental switching in the parasitic
nematode Strongyloides ratti. Proc. Biol. Sci. 263: 201-208.
41 | Parasitic Association
4. Wharton, D. A. (1986). A functional biology of nematodes.
The Johns Hopkins University Press, Baltimore, MD
5. Behm, C.A. (1997). The role of trehalose in the physiology of
nematodes. Int. J. Parasitol. 27: 215-229.
6. Halton, D. W. (1997). Nutritional adaptations to parasitism
within the platyhelminthes. Int J Parasitol. 27: 693-704.
7. Parasitism: Bullies of Wild Life, the Bird World Wild life
Magazine, 1997.
8. Kawecki TJ. Red queen meets Santa Rosalia arms races and
the evolution of host specialization in organisms with parasitic
lifestyles. Am Nat. 1998;152:635-651.
9. Grewal, P.S. (2000). Enhanced ambient storage stability of an
entomopathogenic nematode through anhydrobiosis. Pest
Management Science 56: 401-406.
10. Dalton J. P. (2004). Role of the tegument and gut in nutrient
uptake by parasitic platyhelminths. Canadian J. Zool. 82: 211-232.
11. Shrihari, N., Mariraj, J., Kumudini, T.S. and Krishna S.
(2011). Intestinal perforation due to Tapeworm: Taenia Solium. J.
Clin. Diagn. Res. 5: 1101-1103.
12. Martin BD, Schwab E Symbiosis. Living together in chaos.
Studies in the History of Biology. 2012;4(4):7-25.
42 | Parasitic Association
Chapter-4
MODES OF DISSEMINATION OF DISEASE CAUSING
PHYTO-PARASITES
Dr. Niteen R. Salve
Assistant Professor in Botany, Jamkhed Mahavidyalaya,
Jamkhed, Dist. Ahmednagar 413201(M.S.), India
Email: niteenrsalve@gmail.com
ABSTRACT: Infectious phyto-parasites disseminate from one
place to another using two different strategies, known as the
active/direct method and the passive/indirect method. The
autonomous process that takes place without external control is
known as active dissemination. Edaphochory, spermatochory,
somatochory are various modes of autonomous dissemination.
Indirect dissemination occurs by various modes such as
anthropochory, entomochory, nematochory, ornithochory,
mycochory, phytoparasitochory, hydrochory, anemochory etc.
KEYWORDS: Edaphochory, spermatochory, somatochory,
anthropochory, entomochory, nematochory, ornithochory,
mycochory, hydrochory, anemochory
1.1 INTRODUCTION
"Anything that prevents a plant from performing to its maximum
potential" is known as the plant disease. Both the biotic and abiotic
types of plant diseases are covered in this definition (Cropwatch,
2023). The plant disease that develops due to activity of phyto-
parasite (pathogen) is called infectious/ biotic disease while the one
that develops due to some environmental factors other than the
pathogen are called abiotic/non-infectious disease. Nutritional
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deficiencies, salt injury, soil densification, ice scorch and sun burn/
sunscald are a few instances of abiotic diseases (Cropwatch, 2023).
While infectious diseases can spread from one susceptible host to
another, the non-infectious ones are not transmitted from a
diseased plant to a healthy plant (Nazarov et al., 2020). The major
steps in infectious disease development that occur usually in a
cyclic manner are- inoculation, penetration, infection, incubation,
reproduction, survival and dissemination (Cropwatch, 2023).
There are various types of phyto-parasite (plant pathogen) and
different modes of dissemination of these plant pathogens in plant
disease development.
1.2 PHYTO-PARASITE DISSEMINATION
The phyto-parasites that cause diseases (plant pathogens) to plants
belong to– the fungi, bacteria, phytoplasmas [Mycoplasma-like
organisms (MLOs)], viruses and viroids, nematodes, parasitic
algae as well as higher parasitic plants.
Dissemination or dispersal of pathogen/ disease refers to the
movement of a plant pathogen from its site of origin or production
to a suitable host or place where it can grow and further establish.
Spores or infectious bodies (acting as an inoculum) are transferred
from one host to another at different distances resulting in the
spread of disease (Sharma, 2023).
In the disease cycle, dissemination is the most vulnerable stage for
pathogen, and its successfully completion leads to the disease
epidemic. This understanding of disease dispersion may be useful
in regulating the spread of the epidemic by predicting the course of
the disease (Waggoner et al., 1983).
1.3 MODES OF PHYTO-PARASITE DISSEMINATION
The two main modes of dissemination of plant pathogens
(dissemination of diseases) are:
1. Direct/active (autonomous) mode
2. Indirect/ passive mode
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The term "direct dissemination" refers to the spread/ dispersal that
occurs in and by the soil, by the seeds, or by other planting
materials like corms, tubers, etc. without any agency, whereas
"passive dissemination" refers to the transport/ transmission that
occurs as a result of physical agents (abiotic) like water, air and the
biological agents (biotic) like man, nematodes, insects, or other
animals (Anonymous, 2011; Singh, 2018).
1. Direct/active (autonomous) Dissemination:
The autonomous dissemination occurs through the soil, the seed or
the vegetative propagating/planting materials. And accordingly,
there are following modes of autonomous dissemination.
A. Edaphochory:
When the dissemination of plant pathogen/ disease occurs through
soil, it may be called as edaphochory (Gr. edaphos= ‘soil; Gr. chory
(khōrein)= 'to spread’). Plant pathogens are disseminated by two
modes through soil that is dissemination in the soil and
dissemination by the soil. When the dissemination occurs due to
movement of the pathogen in soil it is called dissemination in soil
and when it is due to the movement of the soil moving the
pathogen, the method is called dissemination by the soil. The latter
is more common than the former method (Singh, 2018). The
example of the former is the movement of nematodes in moist soil
to reach their host. But the distance is not much significant from
the real dissemination point of view. The species of Pythium and
Phytophthora produce motile zoospores that disseminate in thin
film of water to reach their suitable hosts. The wilt causing fungi
(Fusarium oxysporum) and root rot pathogens are practically
immobile and use soil as the site for survival only instead of for
dissemination.
The mode of dissemination of pathogen by the soil refers to the
movement of soil together with plant parts and propagation
materials from from one location to another. Thus, diseases may
be introduced into the orchard from the contaminated nursery soil.
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For instance, the papaya plant in the nursery infected with stem/
foot rot of papaya disease (Refer appendix below for the causal
organism) may bring the disease to new places.
B. Spermatochory:
When the dissemination of plant pathogen/ disease occurs through
seed, it may be called as spermatochory (Gr. sperma= ‘seed; Gr.
chory (khōrein)= 'to spread’). Since seeds are dormant structures,
pathogens hardly ever reside in those. However, during crop
harvest, the pathogen's dormant structures could readily combine
with and move with seeds to disseminate the pathogens. The
dormant structures of the pathogen such as sclerotia of ergot, seeds
of Cuscuta, the cockles of cereal grains, smut sori, cysts containing
nematode larvae etc. contaminate seeds of host. The diseases like
ear-cockle of wheat, ergot of cereals and grasses, smuts of cereals
disseminate by this mode. Apart from contaminating the dormant
structures, the pathogens may also be present on seeds externally
initially and reside inside the seeds later (e.g. loose smut of wheat,
Angular leaf spot/ Bacterial blight/ Black arm of cotton, Bacterial
leaf blight of rice) (Singh, 2018).
C. Somatochory:
When the dissemination of plant pathogen/ disease occurs through
the plant material other than the true seed such as vegetative
propagation materials/ planting materials, it can be called as
somatochory (Gr. soma= ‘body; Gr. chory (khōrein)= 'to spread’).
Vegetative planting materials (tubers, bulbs, cuttings or rhizomes
etc.) are the means of dissemination of almost all virus and viroid
diseases of vegetatively propagated plants (like potato, citrus,
banana, etc.) such as potato spindle tuber disease, citrus exocortis,
and bunchy top of banana; few fungal diseases (such as the late
blight and wart disease of potato) and also some bacterial diseases
(such as the citrus canker and citrus greening) (Singh, 2018).
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2. Indirect/ passive Dissemination:
The indirect dissemination occurs through the external agency of
the man, insects, nematodes, birds, fungi, phanerogamic parasitic
plants, water, air etc.
A. Anthropochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of man, it is referred to as anthropochory (Gr.
anthropos= ‘man/ human’; Gr. chory (khōrein)= 'to spread’). The
phyto-parasites causing disease can disseminate from one location
to another over a short or long distance only through the agency of
man who uses such infected vegetatively propagated materials like
tubers, corns, bulbs, bulbils, rhizomes, cuttings, etc. of plants such
as potato, sweet potato, sugarcane, banana, and many ornamentals
and fruit trees for cultivation. Man has introduced many plant
diseases in new areas crossing the borders of nations and
continents. For example, the diseases like citrus canker, downy
mildew of grapevines, powdery mildew of grapevines spread over
a longer distance due to such activities of man only (Parthasarathy
et al., 2024). Man should be held responsible for the introduction
of pathogens through contaminated seeds from one country to
another through international seed trade if quarantine and
certification norms are not followed. Karnal bunt (origin- Karnal,
Haryana) was native to India but disseminated not only to Mexico
and Europe but also to different parts of India through infected
seeds carried by humans (Singh, 2018; Iquebal, 2021).
B. Entomochory:
When the dissemination of plant pathogen/ disease occurs through
insect vectors, it is known as entomochory (Gr. entomo= ‘insect’;
Gr. chory (khōrein)= 'to spread’). The list of plant diseases caused
by bacteria and passively transmitted by insects is long and
includes the citrus canker, citrus greening, fire blight of apples, wilt
of potato and other solanaceous crops, bacterial bean blights,
crown gall, bacterial spot, and canker of stone fruits, among many
47 | Parasitic Association
others (Agrios, 2008). Insects play the major role in dissemination
of viruses that cause diseases in plants. Insect vectors are the only
means of transmission for the great majority of plant diseases. The
aphids and leafhoppers, which primarily spread mosaic type (e.g.,
Tobacco mosaic, Lettuce mosaic disease) and the yellows-type
viruses (e.g., Aster yellows, Curly top of sugar beet) respectively,
are the main vectors. Some viruses can also be spread by banana
aphids (e.g., Bunchy top of banana), whiteflies (e.g., okra yellow
vein mosaic), green leaf-hoppers (e.g., Rice Tungro Disease),
grasshoppers (transfers mechanically the Tobacco mosaic virus),
thrips (Spotted wilt of tomato), mites (e.g., Wheat streak mosaic
virus), and a few types of beetles (Cowpea mosaic) and caterpillars
(Shurtleff et al., 2023). When the virus-free insect vector feeds on
a plant that is already infected, insect ingests the virus particles
while sucking the sap from the plant. And, then the virus is
disseminated horizontally while feeding on healthy plant. The
insects may transfer the viruses vertically to their offsprings (Wu
et al., 2022).
C. Nematochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of nematodes (thread like animals), it may be called as
nematochory (Gr. nematos= ‘thread; Gr. chory (khōrein)= 'to
spread’). Nematodes act as vectors in the dissemination of a
number of bacterial, viral, and fungal diseases. Tundu disease of
Wheat (Yellow ear rot/ spike blight) is caused by bacterium
Rathayibacter tritici Syn. Coryinebacterium tritici only in
presence of its vector nematode called Anguina tritici. This
nematode is responsible for the formation of seed galls, also called
as ear cockle, in wheat (Bamdadian, 1973; Bockus, 2010;
Tambong, 2022). Hewitt et al. (1958) for the first time showed that
plant virus called Grapevine fanleaf virus (GFLV) is disseminated
by ectoparasite nematode vector called Xiphinema index (Andret-
Link et al., 2004; Singh et al., 2020). The other three genera of
nematodes that act as vectors for plant viruses are Longidorus,
Trichodorus and Paratrichodorus (Singh, 2018).
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D. Ornithochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of birds, it is known as ornithochory (Gr. ornis = ‘bird;
Gr. chory (khōrein)= 'to spread’). The birds that feed on insect
vectors are believed to disseminate plant pathogens unintentionally
at a distance where the vectors themselves cannot reach. Birds feed
on fruits of Dendrophthoe falcata, commonly called Loranthus, the
common parasitic flowering plants and spread the seeds through
their excreta. Some birds disseminate another parasitic plant
Cuscuta, commonly known as dodder while carrying the stem
pieces of plant as cuttings actually taken away for building the
nests of birds (Singh, 2018).
E. Mycochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of fungi, it can be called as mycochory (Gr. mykos =
‘fungi; Gr. chory (khōrein)= 'to spread’). The parasitic soil fungi
act as vectors for both the bacteria and viruses. For instance, the
genus Olpidium of fungi serves as a vector for numerous plant
viruses (Sutela et al., 2019). Olpidium brassicae
(Chytridiomycetes fungus) is a vector of viruses such as lettuce big
vein virus ((LBVV), tobacco stunt virus (TSV), tobacco necrosis
virus (TNV) (Grogan and Campbell, 1966). There are two methods
of acquisition of virus by the vector known as in vitro and in vivo.
The viruses do not exist within the resting spores of their vectors
when they are acquired in vitro; however, when they are acquired
in vivo, they do exist within the resting spores of their vector.
(Campbell, 1968). The five species of fungal vectors are
responsible for the dissemination of thirty soil-borne viruses/
virus-like particles either in vitro or in vivo (Campbell, 1996).
F. Phytoparasitochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of phanerogamic phytoparasite, it may be called as
phytoparasitochory (Gr. phyto= ‘plant’; Gr. parasito= ‘parasite’;
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Gr. chory (khōrein)= 'to spread’). The phanerogamic phyto-
parasites such as the species of Cuscuta (the only parasitic genus
in the family Convolvulaceae) act as the vectors for the
dissemination of virus pathogens (Kaiser et al., 2015). Cuscuta
lives as an obligate total stem parasite on host plants. It establishes
contact with the host by producing haustoria. The transmission of
viruses occurs through these haustoria of Cuscuta from one host
plant to other.
G. Hydrochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of water, it is known as hydrochory (Gr. hydor= ‘water;
Gr. chory (khōrein)= 'to spread’). Certain pathogens, like bacterial
rice blight, wilt fungi, root and collar rot pathogens, and red rot
fungus, have dormant structures that are disseminated over a short
distance through water flow available in the field after irrigation or
rain. The contents of pustules, sori, bacterial ooze, cankers, etc. are
splashed away to a large extent by the forceful water drops from
sprinkler irrigation or heavy rain drops (Singh, 2018).
H. Anemochory:
When the dissemination of plant pathogen/ disease occurs through
the agency of air/ wind, it is referred to as anemochory (Gr. anemos
= ‘wind; Gr. chory (khōrein)= 'to spread’). The plant pathogenic
fungal spores disseminated by air currents are light weight
(buoyant) and produced in huge quantities such as the conidia of
powdery and downy mildew, late blight of potato (Phytophthora
infestans), the urediospores of rusts and the spores of loose smut
of wheat and barley (Ustilago tritici and U. nuda). The
basidiospores of wheat stem rust disseminate for a short distance
while the urediospores at a long distance (Prakash et al., 2021).
The urediospores of wheat stem rust (Puccinia graminis tritici) are
reported to travel by wind thousands of miles (long distance
dissemination) without losing viability, sometimes crossing the
borders of states, nations as well as the continents (Stakman &
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Christensen, 1946; Singh, 2018). Like the fungal spores, the seeds
of phanerogamic plant parasites are also disseminated by wind.
1.4 CONCLUSION
Plant pathogens thus can be disseminated by soil, seed, non-seed
propagating materials, man, insects, nematodes, birds, fungi, wind,
water etc. Plant dissemination may be short distance (e.g.
basidiospores of rust) or long distance (urediospores of rust) and
results in plant disease epidemics. In addition to help in spreading
the plant diseases, the dissemination of pathogen is necessary for
its life cycle to continue and also for its (pathogen’s) evolution.
The parasitic fungi, nematodes and insects act as the vectors of
plant viruses. Understanding the dissemination mechanism is
crucial for managing plant diseases effectively, by breaking the
infection chain itself.
1.5 APPENDIX- LIST OF IMPORTANT PLANT DISEASES
(Kind of pathogen**- A-Alga, B- Bacterium, F-Fungus, H-Higher
plant, M-Mycoplasma, N-Nematode, P- Phytoplasma, V-Virus,
Vd-Viroid)
Sr.
No.
Name of the Disease
Botanical Name of the
causing organism
**
BACTERIAL DISEASES
1.
Citrus canker
Xanthomonas axonopodis pv.
Citri or
Xanthomonas citri subsp. Citri
B
2.
Angular leaf spot*/
Bacterial blight/ Black
arm of cotton
Xanthomonas campestris
pathovars (pv) malvacearum
B
3.
Common blight of
beans
Xanthomonas campestris pv
phaseoli
B
4.
Bacterial blight of
mango
Pseudomonas syringae
pv. Syringae
B
5.
Canker of mango
Xanthomonas campestris
pv. Mangiferaeindicae
B
6.
Bacterial leaf blight of
rice
Xanthomonas campestris pv
oryzae or
Xanthomonas oryzae pv.
Oryzae
B
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7.
Bacterial leaf streak of
rice
Xanthomonas oryzae
pv. oryzicola
B
8.
Bacterial blight or
stripe of
Cereals
Xanthomonas campestris pv
translucens
B
9.
Angular leaf spot of
cucumber
Pseudomonas syringae,
pathovars (pv.)
Lacrymans
B
10.
Wildfire of tobacco
Pseudomonas syringae pv.
Tabaci
B
11.
Bacterial speck of
Tomato
Pseudomonas syringae pv.
Tomato
B
12.
Citrus greening
Candidatus liberobacter
asiaticus
Liberobacter asiaticum
B
13.
Red stripe/ top rot of
sugarcane
Pseudomonas rubrilineans
Acidovorax avenae
subsp. Avenae
B
14.
Bacterial wilt of potato
and other solanaceous
crops
Ralstonia
solanacearum (former
Pseudomonas solanacearum)
B
15.
Ratoon stunting of
sugarcane
Clavibacter xyli sub sp. xyli or
Leifsonia xyli subsp. xyli
B
16.
Crown gall of apple
Rhizobium radiobacter
Syn. Agrobacterium
tumefaciens
B
17.
Tundu disease of
Wheat (Yellow ear rot)
Rathayibacter tritici
Syn. Coryinebacterium tritici
Syn. Clavibacter tritici
B
FUNGAL DISEASES
PHYCOMYCETES
18.
Club root of cabbage
Plasmodiophora brassicae
F
19.
Wart Disease of Potato
Synchytrium endobioticum
F
20.
Damping off of
seedling
Pythium sp.
F
21.
Stem/ Foot rot of
papaya
Pythium aphanidermatum
F
22.
Late blight of potato
Phytophthora infestans
F
23.
White rust of crucifers
Albugo candida
Syn. Cystopus candidus
F
24.
Green ear disease of
bajra
Sclerospora graminicola
F
25.
Downy mildews
Peronospora spp.
F
26.
Downy mildew of peas
Peronospora viciae
F
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Syn. Peronospora pisi
27.
Downy mildew of bajra
(Green ear disease)
Sclerospora graminicola
F
28.
Downy mildew of
sorghum
Peronosclerospora sorghi
F
29.
Downy mildew of
maize
Peronosclerospora maydis
F
30.
Downy mildew of
crucifers
Peronospora parasitica
F
31.
Downy mildew of
cucurbits
Pseudoperonospora cubensis
F
32.
Downy mildew of
grapevine
Plasmopara viticola
F
ASCOMYCETES
33.
Powdery mildews
Erysiphe spp.
F
34.
Powdery mildew of
cereals (wheat)
Blumeria graminis Syn.
Erysiphe graminis
Erysiphe graminis var. tritici
(for wheat)
F
35.
Powdery mildew of
peas
Erysiphe polygoni
F
36.
Powdery mildew of
apple
Podosphaera leucotricha
F
37.
Powdery mildew of
cucurbits
Erysiphe cichoracearum
F
38.
Powdery mildew of
grapevine
Uncinula necator
F
39.
Ergot of cereals and
grasses
Claviceps purpurea
F
40.
Ergot of rye
Claviceps purpurea
F
41.
Ergot of pearl millet
(bajra)
Claviceps fusiformis
F
42.
Leaf curl of peaches
Taphrina deformans
F
43.
Stripe disease of barley
Pyrenophora graminea
Syn. Helminthosporium
gramineum
F
44.
Brown spot disease of
rice/
Helminthosporium
Leaf spot
Bipolaris oryzae
Syn. Cochliobolus miyabeanus
(Sexual stage/ teleomorph)
Helminthosporium oryzae
(asexual stage/ anamorph)
F
BASIDIOMYCETES
45.
Rust of wheat (Stem/
Black rust of wheat)
Puccinia graminis
F
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Syn. Puccinia graminis var,
tritici
46.
Yellow/ stripe rust of
wheat
Puccinia striiformis
F
47.
Brown/ leaf rust of
wheat
Puccinia recondite
Syn. Puccinia triticina
F
48.
Rust of bajra
Puccinia substriata
Syn. Puccinia penniseti
F
49.
Rust of maize
Puccinia sorghi
F
50.
Rust of jowar
Puccinia purpurea
F
51.
Rust of pea
Uromyces pisi
F
52.
Rust of gram
Uromyces ciceris-arientini
F
53.
Rust of linseed
Melamspora lini
F
54.
Coffee leaf rust
Hemileia vastatrix
F
55.
Loose smut of wheat
Ustilago tritici
Ustilago nuda tritici
F
56.
Smut of barley
(Covered smut of
barley)
Ustilago hordei
F
57.
Smut of sugarcane
Sporisorium scitamineum
Syn. Ustilago scitaminea
F
58.
Smut of maize (Corn
smut)
Mycosarcoma maydis
Syn. Ustilago maydis
F
59.
Smut/ Grain smut/
Kernel smut/ Covered
smut/ Short smut of
jowar (sorghum)
Sphacelotheca sorghi
F
60.
Smut of pearl millet
(Bajra smut)
Tolyposporium penicillariae
F
61.
Leaf smut of rice
Entyloma oryzae
F
62.
Bunt of wheat
Ustilago tritici
Syn. Tilletia tritici
F
63.
Karnal bunt of wheat
Tilletia indica
Syn. Neovossia indica
F
64.
Common bunt/ Hill
bunt/ Stinking smut of
wheat
Tilletia caries and
Tilletia laevis Syn. T. foetida
F
65.
Bunt/ Kernel Smut/
Black smut of rice
Tilletia barclayana
F
DEUTEROMYCETES
66.
Red rot of sugarcane
Colletotrichum falcatum
(imperfect stage)
Syn. Physalospora
tucumanensis (Perfect stage)
F
54 | Parasitic Association
67.
Paddy blast (Blast of
rice)
Pyricularia oryzae (Asexual
stage/anamorph)
Syn. Magnaporthe oryzae
(Sexual stage/ teleomorph)
F
68.
Wilt of Arhar (pigeon
pea)
Fusarium oxysporum
Syn. Fusarium oxysporum f.
udum
F
69.
Wilt of chick pea
Fusarium oxysporum
Syn. Fusarium oxysporum f.
ciceris
70.
Wilt of cotton
Fusarium oxysporum
Syn. Fusarium oxysporum f.
vasinfectum
F
71.
Early blight of potato
Alternaria solani
F
72.
Early blight of tomato
Alternaria spp.
F
73.
Tikka disease of
groundnut
Nothopassalora personata
Syn. Cercospora personata
F
VIRAL DISEASES
74.
Yellow vein of Okra
Bhendi yellow vein mosaic
virus (BYVMV) or okra
yellow vein mosaic (OYVMV)
(Geminiviridae)
V
75.
Tobacco mosaic
disease
Tobamovirus (Tobacco mosaic
virus) (TMV)
V
76.
Curly top of sugar beet
Curtovirus (Geminiviridae)
V
77.
Bunchy top of banana
Banana bunchy top virus
(BBTV) (Circoviridae)
V
78.
Spotted wilt of tomato
Tomato spotted wilt virus
(TSWV) (Tospoviruses)
(Bunyaviridae)
V
79.
Rice Tungro Disease
(RTD)
Rice tungro baciliform virus
(RTBV) and rice tungro
spherical virus (RTSV)
V
80.
Potato spindle tuber
disease
Potato spindle tuber viroid
(PSTVd) (Pospiviroid
subgroup)
Vd
81.
Cadang-cadang disease
of coconut
Coconut cadang-cadang viroid
(Cocadviroid subgroup)
Vd
82.
Citrus exocortis
Citrus exocortis viroid (CEVd)
(Pospiviroid subgroup)
(PSTVd) of Pospiviroideae
Vd
83.
Apple scar skin
Apple scar skin viroid
(ASSVd) (Apscaviroid
subgroup) of Pospiviroideae
Vd
55 | Parasitic Association
NEMATODAL DISEASES
84.
Ear-cockle of wheat
Anguina tritici
N
85.
Root Knot of
Vegetables
Meloidogyne spp.
N
86.
Molya Disease of
Barley and Wheat
(cereal root eelworm)
(Cereal cyst Nematode)
Heterodera avenae
N
87.
Potato cyst Nematode
Globodera spp.
N
88.
Soybean cyst nematode
Heterodera glycines
N
ALGAL DISEASES
89.
Red rust of tea
Cephaleuros virescens
A
90.
Orange rust of tea
Cephaleuros parasitica
A
MYCOPLASMA LIKE ORGANISMS/ PHYTOPLASMA
DISEASES
91.
Mycoplasma disease of
potato
Mycoplasma-like organisms
(MLOs)
P
Purple top roll of potato
Mycoplasma-like organisms
(MLOs)
M
Witches’ Broom of
potato
Mycoplasma-like organisms
(MLOs)
M
Marginal flavescence
Mycoplasma-like organisms
(MLOs)
M
92.
Grassy shoot of
sugarcane
Mycoplasma-like organisms
(MLOs)
P
93.
Sandal spike (Spike
disease of sandal)
Mycoplasma-like organisms
(MLOs)
P
94.
Little leaf of brinjal
Mycoplasma-like organisms
(MLOs)
P
1.6 REFERENCES
1. Agrios, G.N. (2008). Transmission of Plant Diseases by
Insects. In: Capinera, J.L. (eds) Encyclopedia of Entomology.
Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-6359-
6_2512
2. Andret-Link, P., Laporte, C., Valat, L., Ritzenthaler, C.,
Demangeat, G., Vigne, E., Laval, V., Pfeiffer, P., Stussi-Garaud,
C., & Fuchs, M. (2004). Grapevine Fanleaf Virus: Still A Major
Threat To The Grapevine Industry. Journal of Plant Pathology,
86(3), 183–195. http://www.jstor.org/stable/41992424
56 | Parasitic Association
3. Anonymous. (2011). Fundamentals of Plant Pathology:
Methods of Dissemination. Retrieved November 30, 2023, from e-
Krishi Shiksha:
http://ecoursesonline.iasri.res.in/mod/page/view.php?id=101360
4. Bamdadian A. (1973). The importance and situation of wheat
diseases in Iran. In: CENTO Panel on Pests and Diseases of Wheat,
Tehran University, College of Agriculture; 5-7 February 1973;
Karaj, Iran. Tehran Iran: Central Treaty Organization (CENTO).
pp. 57-63
5. Blanc, S. (2008). Vector Transmission of Plant Viruses. in
Encyclopedia of Virology (Third Edition). pp. 274-282.
https://doi.org/10.1016/B978-012374410-4.00433-7.
6. Bockus WW, Bowden RL, Hunger M, Morrill WL, Murray
TD, Smiley RW. (2010). Compendium of Wheat Disease. 3rd ed.
St Paul, Minnesota, U.S.A.: The American Phytopathological
Society. p. 117
7. Campbell, R N (1968). Transmission of tomato bushy stunt
virus unsuccessful with Olpidium. Plant Disease Reporter, Vol.
52, 379-80.
8. Campbell, R N (1996). Fungal Transmission of Plant Viruses.
Annual Review of Phytopathology. Vol. 34:87-108.
https://doi.org/10.1146/annurev.phyto.34.1.87.
9. Cropwatch (2023). Cropwatch Website. Plant Disease:
Pathogens and Cycles. University of Nebraska–Lincoln, US.
https://cropwatch.unl.edu/soybean-management/plant-disease
10. Grogan R G and R. N. Campbell (1966). Fungi as Vectors and
Hosts of Viruses. Annual Review of Phytopathology Vol. 4. pp. 29-
52. https://doi.org/10.1146/annurev.py.04.090166.000333
11. Iquebal MA, Mishra P, Maurya R, Jaiswal S, Rai A, Kumar
D. (2021). Centenary of Soil and Air Borne Wheat Karnal Bunt
Disease Research: A Review. Biology (Basel). 2021 Nov
57 | Parasitic Association
9;10(11):1152. doi: 10.3390/biology10111152. PMID: 34827145;
PMCID: PMC8615050.
12. Kaiser B, Vogg G, Fürst UB, Albert M. (2015). Parasitic
plants of the genus Cuscuta and their interaction with susceptible
and resistant host plants. Front Plant Sci. 4;6:45. doi:
10.3389/fpls.2015.00045. PMID: 25699071; PMCID:
PMC4316696.
13. Nazarov PA, Baleev DN, Ivanova MI, Sokolova LM,
Karakozova MV (2020). Infectious Plant Diseases: Etiology,
Current Status, Problems and Prospects in Plant Protection. Acta
Naturae. 2020 Jul-Sep;12(3):46-59. doi:
10.32607/actanaturae.11026. PMID: 33173596; PMCID:
PMC7604890.
14. Parthasarathy, S; P. Lakshmidevi, V.K. Satya, C.
Gopalakrishnan (2024). Plant Pathology and Disease
Management: Principles and Practices. CRC Press. Elite
Publishing House. UK.
15. Prakash R, Verma O P, Singh J, Pandey S, Banchhor G, Arya
S, Wavare S, Mondhe M, Mazumdar P (2021). Technical Booklet
No.02 (2020-21): Rust of Wheat. Government of India, Ministry
of Agriculture & Farmer’s Welfare. Faridabad.
https://ppqs.gov.in/sites/default/files/wheat_rust-english.pdf
16. Sharma S (2023). Dispersal and survival of the Plant
pathogens. In Fundamentals of Plant Pathology- Department of
Plant Pathology, JNKVV.
http://www.jnkvv.org/PDF/04042020185331SKT.pdf
17. Shurtleff, M C, A Kelman, M J. Pelczar, R M. Pelczar (2023).
BritannicaWebsite, Plant Disease Transmission.
https://www.britannica.com/science/plant-disease/Transmission
18. Singh, R. S. (2018). Introduction to Principles of Plant
Pathology, Fifth Edition. New Delhi: Medtech, a division of
Scientific International.
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19. Singh, S; Awasthi, L; Jangre, A & Nirmalkar, V. (2020).
Transmission of plant viruses through soil-inhabiting nematode
vectors. 10.1016/B978-0-12-818654-1.00022.
20. Stakman, E. C., & Christensen, C. M. (1946). Aerobiology in
Relation to Plant Disease. Botanical Review, 12(4), 205–253.
Retrieved from http://www.jstor.org/stable/4353339
21. Sutela, S; Poimala, A; Vainio, E J (2019). Viruses of fungi and
oomycetes in the soil environment, FEMS Microbiology Ecology,
95 (9), fiz119, https://doi.org/10.1093/femsec/fiz119
22. Tambong, T; J. (2022). Bacterial Pathogens of Wheat:
Symptoms, Distribution, Identification, and Taxonomy.
IntechOpen. doi: 10.5772/intechopen.102855
23. Waggoner, P. E., Green, J. A., & Smith, F. B. (1983). The
Aerial Dispersal of the Pathogens of Plant Disease [and
Discussion]. Philosophical Transactions of the Royal Society of
London. Series B, Biological Sciences, 302(1111), 451–462.
http://www.jstor.org/stable/2396016
24. Wu W, Shan HW, Li JM, Zhang CX, Chen JP, Mao Q. (2022)
Roles of Bacterial Symbionts in Transmission of Plant Virus by
Hemipteran Vectors. Front Microbiol. 27;13:805352. doi:
10.3389/fmicb.2022.805352. PMID: 35154053; PMCID:
PMC8829006.
59 | Parasitic Association
Chapter-5
IMPACT AND CLASSIFICATION OF TRYPANOSOMA
PARASITES
K. Ajintha1, Dr. J. Shifa Vanmathi2*, Dr. M. Sithi Jameela3, Dr.
M. I. Zahir Hussain2, R. Marivignesh1, P. Chithaiya1
1.Research scholar, Department of Zoology, Sadakathullah Appa
College (Autonomous), Rahmath Nagar, Tirunelveli-627011
Affiliated to Manonmaniam Sundaranar University, Tirunelveli,
Tamilnadu, India.
2.Assistant professor, Department of Zoology, Sadakathullah
Appa College (Autonomous), Rahmath Nagar, Tirunelveli-627011
Affiliated to Manonmaniam Sundaranar University, Tirunelveli,
Tamilnadu, India.
3. Associate professor, Department of Zoology, Sadakathullah
Appa College (Autonomous), Rahmath Nagar, Tirunelveli-627011
Affiliated to Manonmaniam Sundaranar University, Tirunelveli,
Tamilnadu, India.
Abstract:
Trypanosoma parasites, a group of protozoan pathogens, exhibit a
complex life cycle involving mammalian hosts and insect vectors,
primarily tsetse flies. This intricate life cycle contributes to the
transmission of devastating diseases such as African
trypanosomiasis (sleeping sickness) and Chagas disease. The
classification of Trypanosoma, rooted in the kingdom Protista and
phylum Euglenozoa, reflects the diversity of species within the
genus. Key taxonomic distinctions include the class Kinetoplastea
and order Trypanosomatida, with notable species like
60 | Parasitic Association
Trypanosoma brucei and Trypanosoma cruzi causing significant
human health impacts.
The life cycle unfolds with the introduction of the parasite into the
mammalian host through the bite of an infected insect vector,
where it undergoes various developmental stages. Trypanosomes
exhibit antigenic variation, challenging host immune responses. In
tsetse flies, the parasites transform through procyclic forms,
ultimately reaching the salivary glands to continue the transmission
cycle. Understanding the nuances of this life cycle is pivotal for
devising effective control strategies.
The impact of Trypanosoma parasites on human populations is
profound, encompassing public health, economics, and societal
well-being. Morbidity and mortality associated with African
trypanosomiasis and Chagas disease pose substantial challenges,
leading to disruptions in agriculture, displacement, and
stigmatization. Chronic health conditions, particularly cardiac and
neurological complications, further contribute to the disease
burden. Limited diagnostic tools and treatment options add
complexity to addressing these infections. This chapter
underscores the critical importance of comprehending the life
cycle, taxonomy, and impact of Trypanosoma parasites. A holistic
approach, combining medical interventions, socio-economic
considerations, and global health initiatives, is essential for
mitigating the multifaceted challenges posed by these parasitic
infections.
Introduction
The Trypanosoma parasite represents a formidable group of
protozoan parasites with significant implications for both human
and animal health. These unicellular organisms are responsible for
causing a range of diseases collectively known as trypanosomiasis.
The genus Trypanosoma includes various species, each adapted to
specific hosts, and their complex life cycles involve transitions
between insect vectors and mammalian hosts (L.V. Kirchhoff, H.B
and Tanowitz,2019)
61 | Parasitic Association
Trypanosoma parasites are primarily transmitted through the bite
of infected tsetse flies, which act as vectors in the transmission
cycle. The consequences of Trypanosoma infections are profound,
leading to debilitating and often fatal diseases in humans and
animals. The two most notable species within this genus,
Trypanosoma brucei, and Trypanosoma cruzi, are causative agents
of African trypanosomiasis (sleeping sickness) and Chagas
disease, respectively.
1. Diversity of Trypanosoma Species:
The genus Trypanosoma encompasses a diverse group of species
with distinct morphologies and host specificities.
While some species primarily infect animals, others have evolved
to exploit humans as their hosts.
2. Transmission Dynamics:
Tsetse flies serve as primary vectors in the transmission of
Trypanosoma parasites, with the transmission cycle involving both
insect and mammalian hosts.
The intricate life cycle of Trypanosoma parasites includes stages
within the insect vector and different developmental forms in the
mammalian host.
3. Human and Animal Impact:
Trypanosoma parasites are responsible for significant diseases
affecting both humans and animals, leading to considerable
morbidity and mortality.
The impact on livestock industries in endemic regions is
substantial, affecting agricultural economies and food security.
4. Trypanosoma brucei and African Trypanosomiasis:
Trypanosoma brucei is the causative agent of African
trypanosomiasis, commonly known as sleeping sickness
(P.B. Hamilton and J.R. Stevens,2017).
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This disease has devastating effects on the central nervous
system, resulting in neurological symptoms, altered sleep patterns,
and cognitive impairment.
5. Trypanosoma cruzi and Chagas Disease:
Trypanosoma cruzi causes Chagas disease, a major public health
concern in Latin America.
The parasite primarily infects heart muscle cells, leading to
cardiac complications and, in some cases, gastrointestinal
involvement.
6. Global Distribution:
Trypanosomiasis is prevalent in specific regions of sub-Saharan
Africa, Latin America, and parts of Asia, reflecting the distribution
of competent vectors.
7. Challenges in Diagnosis and Treatment:
Diagnosis of Trypanosoma infections presents challenges due to
the variable clinical presentation and the need for specialized
laboratory techniques.
Treatment options are often limited, with some drugs having
associated toxicities and the emergence of drug-resistant strains.
Classification of Trypanosoma parasites :
Understanding the intricate biology of Trypanosoma parasites and
their interactions with hosts is pivotal for devising effective control
and prevention strategies. This introduction sets the stage for a
detailed exploration of the molecular, immunological, and
epidemiological aspects of Trypanosoma infections, shedding The
classification of Trypanosoma parasites involves organizing these
protozoan parasites into various taxonomic categories based on
their characteristics and evolutionary relationships. The
classification below is a general overview based on the available
information up to that point. Please note that changes may have
occurred since then.
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Kingdom:
Protista Trypanosoma parasites belong to the kingdom Protista, a
diverse group of eukaryotic microorganisms.
Phylum:
Euglenozoa Within the kingdom Protista, Trypanosoma is
classified under the phylum Euglenozoa, which includes a variety
of flagellated protists.
Class:
Kinetoplastea Trypanosoma parasites are further classified into the
class Kinetoplastea, which is characterized by the presence of a
unique mitochondrial structure called the kinetoplast.
Order: Trypanosomatida The order Trypanosomatida includes
various genera of kinetoplastids, with Trypanosoma being one of
the prominent genera. This order is known for its diversity of
parasitic forms.
Family: Trypanosomatidae Trypanosoma parasites are placed
within the family Trypanosomatidae, which encompasses several
genera of kinetoplastids.
Genus: The genus Trypanosoma includes a variety of species, each
adapted to specific hosts and often associated with distinct
diseases.
Important Species: (Marc Desquesnes,et.al.,2013)
1. Trypanosoma brucei:
Causes African trypanosomiasis (sleeping sickness) in humans
and nagana in animals.
Subspecies include T. b. gambiense and T. b. rhodesiense.
2. Trypanosoma cruzi:
Causes Chagas disease in humans.
Transmitted by triatomine bugs.
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3. Trypanosoma congolense, Trypanosoma vivax, etc.:
Various species that cause diseases in animals, especially in
cattle.
Subspecies and Variants:
Depending on the species, there may be subspecies or variants
associated with specific geographic regions or host preferences.
Light on the complex dynamics of these parasitic associations and
their broader implications for global health
The life cycle of Trypanosoma parasites:
The life cycle of Trypanosoma parasites is complex and involves
alternating between a mammalian host and an insect vector,
typically a tsetse fly. There are variations in the life cycle
depending on the species of Trypanosoma, but the general pattern
is as follows:
I. Infection in Mammalian Host:
1. Introduction through Vector Bite:
Trypanosoma parasites are introduced into the mammalian host's
bloodstream when an infected tsetse fly takes a blood meal.
2. Bloodstream Stage (Trypomastigote Form):
In the bloodstream, the parasites exist as extracellular
trypomastigotes.
They can evade the host's immune system by periodically
changing their surface proteins (antigenic variation).
3.Proliferation and Dissemination:
The parasites proliferate and disseminate throughout the
bloodstream, potentially infecting various tissues.
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4.Cellular Invasion (Tissue Stage):
Trypanosomes can invade various tissues, leading to specific
clinical manifestations depending on the species. For example,
Trypanosoma brucei can invade the central nervous system.
II. Uptake by Tsetse Fly:
1. Blood Meal:
An uninfected tsetse fly takes a blood meal from an infected
mammalian host, ingesting bloodstream trypomastigotes.
2. Differentiation in the Fly Midgut :
In the midgut of the tsetse fly, trypomastigotes transform into
procyclic forms.
3. Migration to Fly Salivary Glands:
The procyclic forms migrate to the salivary glands of the tsetse
fly.
III. Transmission to Mammalian Host:
1. Vector's Next Blood Meal:
During the next blood meal taken by the tsetse fly, parasites in
the salivary gland are injected into the mammalian host. (Barbosa
A,et.al.,2017)
2. Bloodstream Stage (Trypomastigote Form):
The life cycle in the mammalian host resumes with the
introduction of trypomastigotes into the bloodstream (Rahman A
H,et.al.,2008).
Impact of Trypanosoma parasites in Human beings:
Impact Trypanosoma parasites have a significant impact on human
populations, particularly in regions where the diseases they cause
are endemic. The two primary species of Trypanosoma that affect
humans are Trypanosoma brucei, causing African trypanosomiasis
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or sleeping sickness, and Trypanosoma cruzi, responsible for
Chagas disease. The impact of these parasites on human beings is
substantial and multifaceted:
1. Public Health Impact:
Morbidity and Mortality: Trypanosoma infections can lead to
severe morbidity and mortality. Both African trypanosomiasis and
Chagas disease can have chronic and acute phases, with
neurological, cardiac, and gastrointestinal complications
(L.V. Kirchhoff, H.B and Tanowitz,2019)
Epidemics: Outbreaks of sleeping sickness and Chagas disease
can occur, particularly in regions with inadequate healthcare
infrastructure and limited axcaccessaadi diagnosis diagnosis and
treatment. diagnosis and treatment.
2. Economic Impact:
Agricultural Productivity: In endemic regions, the diseases
caused by Trypanosoma parasites can impact agricultural
productivity. Infected individuals may experience fatigue,
lethargy, and cognitive impairment, affecting their ability to work.
Livestock Industry: Trypanosoma brucei affects both humans
and animals, leading to a condition known as nagana in livestock.
This has economic implications for the livestock industry in
affected areas (P.B. Hamilton and J.R. Stevens,2017)
3. Societal Impact:
Displacement and Migration: The impact of Trypanosoma
infections can contribute to population displacement. People
affected by Chagas disease, for example, may migrate to urban
areas in search of better healthcare.
Stigmatization: Individuals with visible symptoms of
Trypanosoma infections may face social stigmatization, impacting
their quality of life and mental health (A.K. Pathak,2009)
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4. Chronic Health Conditions:
Cardiac Complications: Chagas disease caused by Trypanosoma
cruzi can lead to chronic heart conditions, including
cardiomyopathy. This can result in heart failure, arrhythmias, and
other cardiac complications.
Neurological Impairment: Trypanosoma brucei, especially in the
late stages, can cause neurological impairment, leading to sleep
disturbances, confusion, and ultimately coma (S. G.
Wilson,et.al.,1963)
5. Challenges in Diagnosis and Treatment:
Diagnostic Delays: Diagnosis of Trypanosoma infections can be
challenging, leading to delays in treatment. Early symptoms may
be non-specific, contributing to underdiagnosis.
Limited Treatment Options: Treatment options for Trypanosoma
infections are limited and can be associated with side effects.
Access to appropriate medications may be challenging in some
regions.
6. Impact on Children:
Congenital Transmission: In Chagas disease, there can be
congenital transmission from infected mothers to their newborns,
leading to potential health issues in children.
7. Global Health Challenges:
Neglected Tropical Diseases: Trypanosoma infections fall under
the category of neglected tropical diseases, contributing to global
health disparities and inequities. (Andrews et al., 1987)
Conclusion :
In summary, the Trypanosoma parasite, characterized by its
intricate life cycle and taxonomic diversity, poses a significant
impact on human populations. The complex transmission
dynamics involving mammalian hosts and insect vectors contribute
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to diseases like African trypanosomiasis and Chagas disease. The
taxonomic classification within the kingdom Protista guides our
understanding of these parasites, particularly the notorious
Trypanosoma brucei and Trypanosoma cruzi. The consequences of
Trypanosoma infections extend beyond public health, influencing
economies, societal dynamics, and agricultural productivity. A
comprehensive approach, integrating scientific advancements,
medical interventions, and socio-economic considerations, is
essential for addressing the multifaceted challenges presented by
these parasitic infections and improving the well-being of affected
populations.
References:
1. N.W. Andrews, Kyong-su Hong, Edith S. Robbins, Victor
Nussenzweig Stage-specific surface antigens expressed during the
morphogenesis of vertebrate forms of Trypanosoma cruzi,1987
2. S. G. Wilson, K. R. S. Morris, I. J. Lewis, and E. Krog The
effects of trypanosomiasis on rural economy With special reference
to the Sudan, Bechuanaland and West Africa, Bull World Health
Organ. 1963; 28(5-6): 595–613.
3. A.K. Pathak, Effect of Trypanosoma spp. on Nutritional status
and performance of livestock Veterinary World, 2009;
Vol.2(11):435-438
4. L.V. Kirchhoff, H.B. Tanowitz, in Encyclopedia of
Microbiology (Third Edition), 2009
5. P.B. Hamilton, J.R. Stevens, in American Trypanosomiasis
Chagas Disease (Second Edition), 2017
6. Marc Desquesnes,Philippe Holzmuller,De-Hua Lai,Alan
Dargantes,4Zhao-Rong Lun and Sathaporn Jittaplapong
Trypanosoma evansi and Surra: A Review and Perspectives on
Origin, History, Distribution, Taxonomy, morphology, Hosts and
Pathogenic Effects. (2013)
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7. Barbosa A, Reiss A, Jackson B,Warren K, Paparini A,
Gillespie G, Prevalence genetic diversity and potential clinical
impact of blood-borne and enteric protozoan parasites in
native mammals from northen Australia. Vet Parasitol.(2017)
238:94-105.
8. Rahman AH, Ibtisam AG, Rihab AY, Salma AR, Gasmir G.
The effect of bovine trypanosomosis and endo-parasitism on
milk production of a dairy farm in The white Nile state, Sudan.
Sudan j vet Res (2008) 23;19-23.
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Chapter-6
IMPORTANCE OF SYMBIOTIC
RELATIONSHIPS IN PLANTS
Dr. R. Rameshwari
Department of Biotechnology, Cauvery College for Women
(Autonomous), Tiruchirappalli – 620 018.
Abstract
Plant-parasite associations are intricate ecological interactions that
involve various organisms deriving nutrients from host plants,
often at the expense of the host's health and productivity. This
dynamic encompasses a diverse range of parasites, including fungi,
bacteria, nematodes, and insects, each with unique mechanisms of
infection and impact. Examples include rusts and smuts causing
cereal crop diseases, bacterial agents inducing gall formations in
woody plants, and nematodes forming characteristic galls on plant
roots. Additionally, obligate parasitic plants like dodder and
broomrapes exemplify fascinating adaptations, relying entirely on
their host for sustenance. The consequences of these associations
extend beyond individual plants, influencing agricultural practices,
ecosystem dynamics, and the delicate balance of plant
communities. Understanding and managing these plant-parasite
interactions are crucial for sustainable agriculture and ecosystem
health.
Key words: Parasite, Mycorrhizae, Endophyte
Plant Parasite associations
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Plant-parasite associations refer to the interactions between plants
and organisms that derive nutrients from plants, often to the
detriment of the plant. These associations can involve various
organisms, including fungi, bacteria, nematodes, insects, and other
parasites. Here are some common types of plant-parasite
associations (Salonen et al., 2001). Plant-parasite associations are
integral components of ecosystems, contributing to the balance of
species and nutrient cycles. Parasites play a role in controlling
plant populations and maintaining biodiversity (Press and Phoenix,
2005). Parasites contribute to the dynamics of plant diseases,
impacting the health and survival of plant populations. Monitoring
and understanding these associations are essential for predicting
and managing disease outbreaks in natural ecosystems and
agricultural settings (Gilligan, 2008). Many plant parasites can
cause diseases in crops, leading to reduced yield and quality.
Farmers and agricultural scientists need to understand these
associations to implement effective disease management
strategies, such as the development of resistant crop varieties,
biological control methods, and the judicious use of pesticides
(Savary et al., 2012). The co-evolution of plants and their parasites
has shaped the genetic diversity and adaptive strategies of both.
Studying these associations provides insights into the evolutionary
dynamics of host-parasite interactions and the development of
resistance mechanisms in plants (Ebert and Fields, 2020). Changes
in climate conditions can influence the prevalence and distribution
of plant parasites. Studying these associations can help predict how
climate change may impact plant health, crop productivity, and
ecosystem dynamics (Ghini 2008).
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Figure 1. Schematic representation of the types of plant-parasite
association
1. Mutualistic Association
Mutualistic associations refer to interactions between two species
in which both partners benefit from the relationship. These
associations are prevalent in nature and can involve various types
of organisms, including plants, fungi, bacteria, and animals. There
are few examples of mutualistic associations (Lanfranco et al.,
2016).
1.1 Mycorrhizal Associations
Mycorrhizal associations are symbiotic relationships between
fungi and the roots of plants. These associations play a crucial role
in the ecology and health of many plant species. There are several
types of mycorrhizal associations, but the two most common are
arbuscular mycorrhizae (AM) and ectomycorrhizae (ECM).
Mycorrhizal associations are of great significance and importance
in both natural ecosystems and agricultural settings. Mycorrhizal
fungi enhance the plant's ability to absorb essential nutrients,
especially phosphorus and nitrogen, from the soil. This is particul
arly important in ecosystems where these nutrients may be limited
(Miransari et al., 2011). Mycorrhizal associations can improve a
plant's resistance to environmental stresses such as drought,
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salinity, and heavy metal toxicity. The extended hyphal network
helps plants access water and nutrients in challenging conditions
(Kapoor et al., 2012). They play a crucial role in nutrient cycling,
carbon sequestration, and the establishment of plant communities.
The diversity of mycorrhizal fungi contributes to overall
biodiversity in ecosystems (Tedersoo et al., 2020).
1.1.1 Arbuscular Mycorrhizae (AM)
The fungi involved in arbuscular mycorrhizal associations belong
to the Glomeromycota phylum, which includes genera such as
Glomus and Rhizophagus (Sturmer et al., 2012). A wide range of
plant species, including many agricultural crops, grasses, and trees,
form arbuscular mycorrhizal associations. This symbiosis is
considered one of the most widespread and ancient mutualistic
interactions between plants and fungi (Bainard et al., 2011).
Arbuscules are branching, tree-like structures formed by the
fungus within the cortical cells of the plant roots. These structures
serve as the sites for nutrient exchange, allowing the transfer of
minerals and water from the fungus to the plant and receiving
photosynthetic products (mainly sugars) in return. The fungal
mycelium extends into the soil, effectively increasing the surface
area for nutrient absorption, particularly phosphorus. (Bonfante –
Fasolo 2018). Arbuscular mycorrhizae are particularly beneficial
in enhancing phosphorus uptake by the plant. The fungus can
access phosphorus in the soil more efficiently than the plant roots
alone, providing the plant with an important nutrient (Bagyaraj et
al., 2015). In addition to phosphorus, arbuscular mycorrhizae can
facilitate the uptake of other nutrients, such as nitrogen, potassium,
and micronutrients, contributing to improved plant nutrition
(Bhantana et al., 2021). The mycorrhizal association enhances the
plant's ability to acquire nutrients from the soil, especially under
conditions of low nutrient availability (Clark et al., 2000).
Arbuscular mycorrhizae can improve plant resistance to various
environmental stresses, such as drought, salinity, and certain
pathogens (Diagne et al., 2020). Arbuscular mycorrhizal
associations have implications for sustainable agriculture.
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Inoculating crops with mycorrhizal fungi can improve nutrient
efficiency and reduce the need for chemical fertilizers (Igiehon et
al., 2017). Arbuscular mycorrhizal associations play a crucial role
in ecosystem functioning, contributing to the health and vitality of
a wide range of plant species. The mutualistic exchange of
nutrients benefits both the fungi and the plants involved, promoting
ecological stability and plant resilience.
1.1.2 Ectomycorrhizae
Ectomycorrhizae (ECM) is a type of mutualistic association
between certain fungi and the roots of plants, predominantly trees,
but also some shrubs. In this symbiotic relationship, the fungal
hyphae form a dense network around the outer surface of the plant
roots, creating a sheath-like structure without penetrating
individual root cells (Agerer, et al., 2006). Ectomycorrhizal fungi
are diverse and belong to various taxonomic groups, including
Basidiomycota (e.g., Boletus, Amanita, and Laccaria genera) and
Ascomycota. These fungi often exhibit a high degree of specificity,
forming associations with particular tree species (Nouhra et al.,
2019). Ectomycorrhizal associations are commonly found in trees,
especially in temperate and boreal forests. Conifers such as pines,
spruces, and firs, as well as some deciduous trees like oaks and
beeches, frequently engage in ectomycorrhizal symbioses (Courty
et al., 2010). The fungal hyphae of ectomycorrhizae form a dense
network known as the Hartig net around the outer layers of the
plant root cells. This net provides an interface for nutrient
exchange between the fungus and the plant (Peterson and
Bonfante, 1994). The fungal mycelium forms a protective sheath
around the plant root tips, enhancing nutrient absorption and
creating a physical barrier against potential pathogens (Phillips,
2017). Ectomycorrhizal fungi assist in the absorption of essential
nutrients, especially nitrogen and phosphorus, from the soil. The
fungus receives carbohydrates, such as sugars, from the plant in
return (Chalot and Brun, 1998). The extensive mycelial network of
ectomycorrhizal fungi can explore a larger volume of soil than
plant roots alone, improving the plant's access to nutrients (Simard
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et al., 2015). Ectomycorrhizae can contribute to increased
resistance to environmental stresses, such as drought, and can also
provide protection against certain soil-borne pathogens (Nasim et
al., 2010). Many tree species that form ectomycorrhizal
associations rely on these fungi for successful seedling
establishment and growth (Horton et al., 2008).
1.2 Endophytic associations
Endophytic associations refer to the symbiotic relationships
between certain microorganisms, typically fungi or bacteria, and
the tissues of plants. Unlike pathogens, which cause diseases in
their host organisms, endophytes live within plant tissues without
causing harm. Instead, they often provide various benefits to the
host plants. Endophytes often engage in mutualistic relationships
with their host plants. They can enhance the plant's growth,
increase tolerance to environmental stresses (such as drought or
disease), and improve nutrient uptake. In return, the plant provides
the endophyte with a protected and nutrient-rich environment
(Ullah et al., 2019). Endophytes contribute significantly to the
overall biodiversity of ecosystems. Different plant species harbor
diverse communities of endophytes, and the types of endophytes
can vary between plant species and even different tissues within
the same plant (Huang et al., 2008). Endophytes have been a source
of bioactive compounds with pharmaceutical potential. Some
endophytes produce secondary metabolites that may have
antimicrobial, anticancer, or other medicinal properties.
Endophytes have been a source of bioactive compounds with
pharmaceutical potential. Some endophytes produce secondary
metabolites that may have antimicrobial, anticancer, or other
medicinal properties (Palanichamy et al., 2018). Certain
endophytes have been studied for their ability to assist in the
remediation of contaminated soils. They can aid in the degradation
or accumulation of pollutants, contributing to environmental
cleanup efforts (Feng et al., 2017).
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1.2.1 Plant Fungal Endophytes
Plant fungal endophytes are fungi that live within the tissues of
plants without causing any apparent harm to the host. These
endophytic fungi are found in various plant species, including
trees, grasses, and crops. Fungal endophytes can be classified into
several groups based on their interactions with host plants and the
benefits they provide. Fungal endophytes are known to produce a
wide variety of bioactive compounds, including secondary
metabolites with potential pharmaceutical applications. Some of
these compounds have demonstrated antimicrobial, anticancer, and
other bioactive properties, making fungal endophytes a subject of
interest in drug discovery (Rai et al., 2021).
1.2.2 Plant Bacterial Endophytes
Plant bacterial endophytes are bacteria that live within the internal
tissues of plants without causing any apparent harm to the host.
Similar to fungal endophytes, these bacteria form symbiotic
relationships with plants, and their presence can offer various
benefits to the host plant. Some bacterial endophytes, especially
those belonging to the genera Rhizobium and Bradyrhizobium, are
known for their ability to fix atmospheric nitrogen into a form that
plants can use. This is particularly important for plants in nitrogen-
poor soils, as it provides a natural source of this essential nutrient
(Puri et al., 2018).
1.2.3 Insect Plant Endophytes
Insect plant endophytes" typically refers to microorganisms, such
as bacteria or fungi, that inhabit the internal tissues of plants and
have specific associations with insects. These interactions can have
various ecological implications, influencing both the plants and the
associated insect populations. The presence of insect plant
endophytes can influence the overall fitness of host plants. By
deterring herbivores or providing other benefits, these endophytes
can contribute to the plant's reproductive success and survival
(Raman et al., 2012). Some insect plant endophytes can influence
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the chemical signaling within plants. This can impact the plant's
response to herbivores and other environmental stresses. In some
cases, the presence of endophytes may trigger the release of
volatile organic compounds that attract or repel insects (Bastías et
al., 2018).
2.0 Pathogenic Association
A pathogenic association refers to a relationship between two
organisms where one organism, known as the pathogen, causes
harm to the other organism, known as the host. In the context of
plants and microorganisms, pathogenic associations often involve
fungi, bacteria, viruses, or other pathogens that can negatively
impact the health and well-being of the host plant.
2.1 Fungal Pathogens
Fungal pathogens are microorganisms that cause diseases in plants,
animals, and humans. In the context of plants, fungal pathogens
can lead to various diseases, affecting crops, ornamental plants,
and natural ecosystems (Gladieux et al., 2011). Rust fungi are a
group of plant pathogens that often produce distinctive rust-colored
spore masses on infected plant tissues. They can infect a wide
range of plants, including crops like wheat, barley, and soybeans.
Powdery mildews are fungal pathogens that form a white, powdery
substance on the surface of infected plant tissues. They affect
various plants, including roses, grapes, cucumbers, and fruit trees
(Saharan et al., 2019).
2.2 Bacterial Pathogens
Bacterial pathogens are microorganisms that can cause diseases in
various organisms, including plants, animals, and humans. In the
context of plants, bacterial pathogens can lead to significant crop
losses and impact agricultural productivity. Xanthomonas
axonopodis causes diseases like citrus canker in citrus plants and
bacterial spot in tomatoes and peppers. Pseudomonas syringae
causes bacterial speck, bacterial spot, and other diseases in a wide
range of plants, including tomatoes, peppers, and beans (Gottig et
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al., 2010). Ralstonia solanacearum causes bacterial wilt in a
diverse range of plants, including tomatoes, potatoes, and bananas
(Manda et al., 2020).
2.3 Viral Pathogens
Viral pathogens are microscopic infectious agents that can cause
diseases in plants, animals, and humans. In the context of plants,
viral pathogens are responsible for a wide range of diseases that
can affect crop yields and quality. Tobacco Mosaic Virus affects a
wide range of plants, including tobacco, tomatoes, and peppers,
causing mosaic patterns on leaves (Hidayat et al., 2019). Potato
Virus Y affects potatoes, tomatoes, and peppers, causing mosaic
and necrotic symptoms (Tsedaley, 2015).
3.0 Nematode Parasitism
Nematode parasitism refers to the relationship between nematodes
(roundworms) and their hosts, where nematodes act as parasites,
feeding on or within the host organism. Nematodes are diverse
organisms found in various environments, and while many are
free-living and beneficial, some are parasitic and can cause
diseases in plants, animals, and humans.
Sedentary Endoparasites: These nematodes establish feeding
sites within the plant tissues. Examples include root-knot
nematodes (Meloidogyne spp.) and cyst nematodes (Heterodera
and Globodera spp.). Ectoparasites: These nematodes feed on the
outer surface of plant roots. Examples include lesion nematodes
(Pratylenchus spp.) and dagger nematodes (Xiphinema spp.)
(Norton, D. C., & Niblack, T. L. 2020. Plant-parasitic nematodes
can cause symptoms such as stunting, yellowing, and reduced
yields in crops. The damage is often a result of feeding,
modification of root tissues, and increased susceptibility to other
pathogens (Reddy 2021).
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4.0 Insect Parasitism
Insect parasitism refers to a relationship in which one insect
species, the parasitoid, exploits and often kills another insect, the
host, for its own development. Unlike predators that typically
consume multiple prey throughout their lifetime, parasitoids
usually have a single host or a few hosts during their development.
The parasitoid-host interaction is a crucial aspect of ecological
balance, influencing population dynamics and community
structure (Salt et al., 1938).
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Chapter-7
COMPREHENSIVE INSIGHTS INTO LYMPHATIC
FILARIASIS: GLOBAL IMPACT, ERADICATION
INITIATIVES, AND CHALLENGES AHEAD
Manjulendra Kumar, Amita Singh, Naheda Anjum, Dileep Kumar
and Vijay Kumar
Department of Zoology, School of Life Sciences
Babasaheb Bhimrao Ambedkar University- Lucknow, Uttar
Pradesh, India, 226025
Corresponding Author Email: manjulendra725@gmail.com
Abstract
This book chapter provides a comprehensive overview of
lymphatic filariasis (LF), the second most prevalent arthropod-
borne infectious disease worldwide. Covering its global
epidemiology, transmission dynamics, and the burden it imposes
on affected individuals, the chapter delves into the social,
economic, psychological, and sociological impacts of LF. The
narrative spans regions heavily affected, such as Southern and
Southeast Asia, Africa, the Pacific, the Americas, and the Middle
East. The discussion extends to the initiatives and milestones set
forth by the World Health Organization (WHO) in the Global
Programme to Eliminate Lymphatic Filariasis (GPELF), launched
in 2000, and reinforced by the London Declaration in 2012. The
narrative outlines the transmission dynamics of LF, emphasizing
the role of specific mosquito vectors and the three human LF
parasites. Addressing the burden of LF, the chapter explores the
psychological, physical, economic, and sociological aspects,
shedding light on the challenges faced by affected individuals and
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communities. It underscores the importance of understanding the
multifaceted impact of LF for effective morbidity management and
disability prevention. Furthermore, the chapter discusses the global
distribution of LF, highlighting current presence and historical
context in the United States, emphasizing the high-risk areas and
populations. It also provides insights into the obstacles faced in
Mass Drug Administration (MDA) initiatives, acknowledging the
achievements and advancements in LF elimination efforts. Finally,
the chapter presents the current status and future goals of the
worldwide initiative for eradicating LF, encapsulating the
objectives of the new Road Map on Neglected Tropical Diseases
from 2021 to 2030. The roadmap includes criteria for validating
LF elimination, surveillance activities post-MDA, and the ultimate
goal of reducing the total population requiring MDA to zero. This
comprehensive exploration of LF serves as a valuable resource for
researchers, healthcare professionals, and policymakers, offering
insights into the challenges and progress in the global fight against
this debilitating disease.
Key words: Wuchereria bancrofti, Lymphatic filariasis, Mass
Drug Administration (MDA).
Introduction
Lymphatic filariasis (LF) is recognized as the second most
prevalent arthropod-borne infectious disease worldwide, affecting
approximately 128 million individuals across 78 countries where it
is endemic (World Health Organization, 2008b). The majority of
lymphatic filariasis (LF) infections are concentrated in humid
tropical regions spanning Asia, Africa, the western Pacific, and
certain parts of the Americas. Approximately 1.3 billion people are
at risk of acquiring new LF infections annually (World Health
Organization, 2008b). Southern and Southeast Asian areas account
for the highest number of individuals at risk, with 891 million
people (68% globally), and India alone harboring 454 million at-
risk individuals (World Health Organization, 2008b). Tropical
Africa follows closely, with an estimated 382 million people at
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risk, representing 30% of the global burden in 2007. A significant
portion of these cases, about 51 million, faces severe
consequences, including disabilities and disfigurement (Lindsay
and Thomas, 2000; Michael and Bundy, 1997; Muturi et al., 2008;
World Health Organization, 2008b). In 2005, countries
participating in the Southeast Asia Programme Review Group
(PRG) for LF elimination aimed to cover nearly 543 million (61%)
of their at-risk population, while African nations targeted 44
million (12%) (World Health Organization, 2008b). Among the
three human LF parasites, Wuchereria bancrofti (Cobbald, 1877)
is the most widespread.
Transmission of lymphatic filariasis has been documented across
Africa, Southeast Asia, and the Pacific, with focal occurrences in
the Caribbean, South America, and the Middle East (Michael &
Bundy 1997). The use of population-level vector control or Mass
Drug Administration (MDA) initiatives commenced in the 1950s
in countries such as India, China, Egypt, and Brazil.
Implementation extended across Oceania (Gordon et. al., 2018)
from the 1960s to the 1990s. In 1997, the World Health Assembly
acknowledged the objective of globally eliminating lymphatic
filariasis as a public health concern by 2020, as outlined in
resolution WHA50.29 (Cox 2000). National programs were
established to interrupt transmission and control morbidity. China
achieved the milestone of eliminating lymphatic filariasis as a
public health problem in 2007, followed by South Korea in 2006
(De-jan et.al., 2013; Cheun et. al., 2009). Coordinated efforts
involving ministries of health, international partners, and the
research community have persisted since the initiation of the
Global Programme to Eliminate Lymphatic Filariasis (GPELF) in
2000, launched by the World Health Organization (WHO 2017).
The commitment to elimination was reinforced with the adoption
of the London Declaration in 2012 (WHO 2000). WHO has
proposed new milestones and targets for eliminating lymphatic
filariasis as a public health problem, aligning with the 2030
objectives of the Sustainable Development Goals.
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Wuchereria bancrofti primarily spreads through mosquitoes, with
Culex and Anopheles species responsible for transmitting the
nocturnally periodic form. In the case of the two subperiodic forms
(nocturnal and diurnal) found in southeastern Asia and the western
Pacific, transmission occurs through specific species within the
genera Aedes, Downsiomyia, and Ochlerotatus. Lymphatic
filariasis (LF) is an illness transmitted by mosquitoes and, in its
more advanced stages, may present as severe swelling of the
lymphatic system, fluid accumulation in the scrotum (hydrocele),
and the development of elephantiasis (Tylor et. al., 2010) In
communities, the spread of infection can be halted through mass
treatment using recommended oral regimens of anti-helmintic
drugs. These medications include albendazole, either on its own or
in conjunction with ivermectin, as well as diethylcarbamazine
citrate and albendazole. The specific choice of these drugs, either
individually or in combination, depends on the particular context.
Epidemiology of Lymphatic filariasis
Currently, there are over 120 million cases of LF worldwide (Joshi,
2018). India, Africa, South-east Asia, the Pacific region, and the
Americas collectively harbor one-third of LF infections each, with
India, Indonesia, Nigeria, and Bangladesh being the most heavily
affected countries, contributing to 70% of global infections (WHO,
2000). Nigeria, in particular, bears a substantial LF burden, ranking
first in Africa and third globally (Hotez et. al., 2012). The
prevalence in Nigeria poses a significant threat, with
approximately 106 million people at risk of the disease (FMoH,
2012). This prevalence spans across all states and geopolitical
zones in Nigeria, with mapping surveys reporting a total of 241
lymphedemas and 205 hydrocele cases (FMoH 2012; Okorie et.
al., 2011).
A. Social Impact of Lymphatic Filariasis (LF)
The social ramifications of chronic Lymphatic Filariasis (LF) are
profound, negatively impacting individuals both socially and
economically. Individuals afflicted with elephantiasis and
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hydrocele often face social marginalization and poverty (Wynd et.
al., 2007). While the extent of social disability varies across
cultures, there is a direct correlation between the severity of the
disease and the level of stigmatization (Evans et. al., 1993; Mujinja
et al., 1997). Among the various consequences, one evident social
impact of lymphatic filariasis is the dropout of affected individuals
from school due to the stigma they experience from their peers,
resulting in limited or no formal education (Eneanya et. al., 2019).
Another consequence is the decreased likelihood of marriage for
affected individuals, particularly women (Eneanya et. al., 2019).
Men also bear a physical and psychological burden, adversely
affecting their marriages and employment prospects (Gyapong et.
al., 2000). It is crucial to recognize that individuals affected by
filariasis often find themselves excluded from social gatherings
and subjected to various forms of stigmatization from friends,
neighbors, and others. Therefore, raising awareness about filariasis
is essential to educate community members, reduce the severity of
stigmatization, and prevent further transmissions.
B. Global Distribution of Lymphatic Filariasis: Current
Presence and Historical Context in the United States
In the United States, Charleston, South Carolina, was the last
known location with lymphatic filariasis, and the infection
disappeared in the early 20th century. Currently, the U.S. territory
of American Samoa is the sole place within the United States
where individuals could potentially contract lymphatic filariasis. In
various regions globally:
Africa
Lymphatic filariasis is prevalent in countries such as Angola,
Benin, Burkina-Faso, Cameroon, Central African Republic, Chad,
Comoros, Congo (Brazzaville), Eritrea, Ethiopia, Gabon, Ghana,
Guinea, Guinea-Bissau, Kenya, Liberia, Côte d’Ivoire,
Democratic Republic of the Congo, Equatorial Guinea,
Madagascar, Malawi, Mali, Mozambique, Niger, Nigeria, Sao
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Tome and Principe, Senegal, Sierra Leone, South Sudan, Sudan,
Tanzania, Togo*, Uganda, Zambia, Zimbabwe.
Asia
Affected countries include Bangladesh, Brunei Darussalam,
Burma (Myanmar), Cambodia*, India, Indonesia, Laos, Malaysia,
Maldives*, Nepal, Philippines, Sri Lanka*, Thailand*, Timor-
Leste (East Timor), Vietnam.
The Caribbean: Lymphatic filariasis is present in the Dominican
Republic and Haiti.
The Middle East: Egypt* and Yemen are areas where the disease
is found.
The Pacific Islands: This category includes American Samoa (a
U.S. Territory), Cook Islands*, Federated States of Micronesia,
Fiji, French Polynesia, Kiribati, Marshall Islands, New Caledonia,
Niue*, Palau, Papua New Guinea, Samoa, Tonga*, Tuvalu,
Vanuatu*, Wallis, Futuna.
South America: Brazil and Guyana are countries affected by
lymphatic filariasis.
(Source: Global Health, Division of Parasitic Diseases and
Malaria)
C. High risk area and population
Lymphatic filariasis (LF) predominantly affects regions with
specific environmental conditions favorable to the transmission of
the disease. Populations vulnerable to LF often reside in tropical
and subtropical areas where the responsible mosquitoes thrive.
Regions with poor sanitation and limited access to healthcare are
particularly at risk. Some of the high-risk areas include:
Regions
Sub-Saharan Africa (e.g., Angola, Nigeria, Democratic
Republic of the Congo)
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Southeast Asia (e.g., India, Indonesia, Bangladesh)
Pacific Islands (e.g., Papua New Guinea, Fiji, Samoa)
Caribbean (e.g., Haiti, Dominican Republic)
Parts of South America (e.g., Brazil, Guyana)
Populations
Rural communities with limited access to healthcare and
sanitation facilities.
Poverty-stricken areas where preventive measures and
treatment are often challenging to implement
Communities with a high prevalence of the responsible
mosquito vectors.
Urban slums with overcrowded living conditions.
Individuals with limited awareness and education regarding
LF prevention.
It's important to note that efforts to control LF often focus on mass
drug administration, mosquito control measures, and improving
sanitation to reduce the risk in vulnerable populations.
Burden of Lymphatic filariasis
The effective management and control of morbidity play crucial
roles in the elimination of filariasis. It is imperative to grasp the
extent of disability induced by lymphatic filariasis (LF) across both
physical and psychosocial aspects of health. While there exists
research on the economic impact of the disease (Krishnamoorthy
1999; Ramaiah et. al., 2000), there is a notable scarcity of
information regarding the social and psychological challenges it
poses (Suma & Shenoy 2003). Understanding the severity levels
associated with each stage of filariasis in terms of physical, mental,
and social dimensions is vital for effective morbidity management.
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Psychological Burden
The psychological burden of lymphatic filariasis (LF) represents a
significant aspect of the overall impact of the disease on
individuals. While much attention has been given to the physical
manifestations and economic consequences of LF, the emotional
and psychological toll is equally noteworthy. Living with LF can
lead to various psychological challenges for affected individuals.
The visible disfigurement caused by the disease, such as swollen
limbs, can result in feelings of shame, embarrassment, and social
stigma. This may lead to a decline in self-esteem and mental well-
being. Individuals with LF may experience anxiety and depression
due to the social isolation and discrimination they often face.
Moreover, the chronic nature of LF, coupled with the potential for
recurrent acute attacks, can contribute to long-term psychological
distress. The uncertainty regarding the progression of the disease
and its impact on daily life can create feelings of helplessness and
fear about the future. Addressing the psychological burden of LF
is crucial for comprehensive care and effective management of the
disease. Incorporating mental health support, counseling, and
community awareness programs can play a vital role in alleviating
the emotional challenges faced by individuals affected by
lymphatic filariasis.
Physical burden
The physical burden of lymphatic filariasis (LF) is substantial and
encompasses a range of health challenges for those affected by the
disease. LF, caused by parasitic worms transmitted through
mosquitoes, primarily affects the lymphatic system. The physical
manifestations include:
Lymphedema
One of the hallmark symptoms of LF is the development of
lymphedema, which involves swelling of limbs, typically the legs
or arms. This condition arises due to the accumulation of lymphatic
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fluid and can result in significant discomfort, reduced mobility, and
functional impairment.
Hydrocele
In males, LF can lead to the accumulation of fluid in the scrotum,
causing hydrocele. This condition results in swelling and can
contribute to pain and difficulty in walking.
Recurrent Acute Attacks
Individuals with LF may experience recurrent episodes of acute
inflammation, known as acute attacks. These episodes can cause
severe pain, fever, and additional swelling, further compromising
the affected individual's quality of life.
Disfigurement and Disability
The visible effects of LF, including swollen limbs and other
physical deformities, can lead to social stigma and discrimination.
This, in turn, may contribute to a decreased quality of life, limited
social interactions, and challenges in employment and daily
activities.
Secondary Infections
The compromised lymphatic system in individuals with LF makes
them more susceptible to secondary bacterial and fungal infections.
These infections can exacerbate the physical symptoms and
contribute to the overall burden of the disease.
Functional Impairments
As LF progresses, individuals may experience reduced mobility
and functionality, impacting their ability to perform daily tasks and
participate in work or social activities.
The physical burden of LF not only affects the individual's health
but also has broader implications for their socio-economic well-
being. Comprehensive management of LF involves not only
treating the physical symptoms but also addressing the
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psychosocial aspects and promoting disability prevention and
rehabilitation.
Economical burden
The economic burden of lymphatic filariasis (LF) is a significant
aspect that goes beyond the direct costs of medical treatment. The
economic impact encompasses various factors that affect both
individuals and communities:
Treatment Costs
Direct medical expenses associated with LF include the costs of
medications, hospital visits, and surgical interventions. The need
for long-term and sometimes repeated treatments can lead to a
considerable financial burden for affected individuals and their
families.
Lost Productivity
LF can result in disability, reduced mobility, and increased
absenteeism from work or school. This leads to lost productivity
both at the individual level and within communities. The economic
impact extends to decreased earning potential and opportunities for
those affected by the disease.
Impact on Livelihoods
Individuals with advanced stages of LF may find it challenging to
engage in regular employment or agricultural activities due to
physical disabilities. This can result in a decline in income and
economic instability for affected households.
Social Stigma and Discrimination
The visible symptoms of LF, such as swollen limbs, can lead to
social stigma and discrimination, making it difficult for individuals
to secure and maintain employment. This exacerbates the
economic burden by limiting opportunities for social and economic
integration.
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Healthcare System Costs
The burden extends to the healthcare system, which must allocate
resources for the diagnosis, treatment, and management of LF
cases. This includes expenses related to public health programs,
awareness campaigns, and infrastructure development to address
the disease.
Educational Impact
LF can also impact education, as affected individuals, particularly
children, may face challenges attending school regularly. This can
result in lower educational attainment and limit future economic
opportunities.
Preventive Measures
Implementing preventive measures, such as mass drug
administration campaigns and vector control programs, requires
financial resources. The economic burden includes the costs
associated with these public health interventions.
Inter-generational Impact: Families affected by LF may face a
cycle of poverty as the disease can be transmitted within
households. The economic burden is not only borne by the current
generation but may also impact future generations.
Addressing the economic burden of LF involves not only medical
interventions but also comprehensive strategies that consider the
broader socio-economic factors contributing to the cycle of poverty
associated with the disease. This may include disability prevention,
rehabilitation programs, and initiatives aimed at improving the
economic prospects of affected individuals and communities.
Sociological burden
The sociological burden of lymphatic filariasis (LF) encompasses
the impact of the disease on the social fabric of communities and
the well-being of individuals within these communities. Several
sociological dimensions contribute to the overall burden:
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Stigma and Social Exclusion: Visible symptoms of LF, such as
swollen limbs or disfigurement, can lead to social stigma and
discrimination. Individuals affected by LF may face exclusion
from social activities, community events, and even family
gatherings, affecting their sense of belonging and social
integration.
Impact on relationships
The physical manifestations of LF can strain interpersonal
relationships. Stigmatization and the challenges posed by the
disease may affect familial bonds, friendships, and romantic
relationships. Individuals with LF may experience isolation and a
sense of being marginalized within their social networks
Gender Dynamics
LF can have distinct gender-related impacts. For example, in areas
where hydrocele is prevalent, affected men may face challenges in
fulfilling traditional gender roles, leading to shifts in family
dynamics. Additionally, the burden of care often falls on women
when family members are affected by LF, influencing their social
roles and responsibilities.
Educational Barriers
Children affected by LF may encounter difficulties in attending
school regularly due to health-related issues. This can lead to
educational gaps and affect their social interactions with peers,
potentially contributing to feelings of exclusion and lower self-
esteem.
Community Perception
Misconceptions and lack of awareness about LF can contribute to
community fear and misunderstanding. This may result in social
isolation for affected individuals and hinder efforts to integrate
them into community life.
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Community Productivity
As LF can lead to disability and reduced productivity, communities
may experience economic challenges. The inability of affected
individuals to fully participate in community activities, including
work and social events, can impact the overall productivity and
cohesion of the community.
Community Resilience:
The presence of LF may strain the resilience of communities,
especially in regions where the disease is endemic. Communities
may face challenges in adapting to the needs of affected individuals
and providing necessary support systems.
Addressing the sociological burden of LF involves fostering
awareness and understanding within communities, promoting
inclusivity, and implementing social support systems. Strategies
should aim to reduce stigma, enhance community resilience, and
empower individuals affected by LF to actively participate in
social life. Collaborative efforts that involve affected individuals,
community leaders, and healthcare professionals are crucial for
creating supportive environments and mitigating the sociological
impact of LF.
Lymphatic filariasis
The term "lymphatic filariasis" encompasses infection with three
closely related nematode worms: Wuchereria bancrofti, Brugia
malayi, and Brugia timori. All three parasites are transmitted
through bites from infected mosquitoes and share similar life
cycles in humans. Adult worms reside in the afferent lymphatic
vessels, while their offspring, the microfilariae, circulate in the
peripheral blood, potentially infecting mosquitoes during feeding.
Transmission dynamics of Lymphatic filariasis
The transmission dynamics of lymphatic filariasis (LF) involve the
complex life cycle of the filarial parasites and the role of specific
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mosquito vectors. Here is an overview of the transmission
dynamics:
Hosts and Vectors
Wuchereria bancrofti, Brugia malayi, and B. timori primarily
infect humans, with minimal epidemiological significance or
absence of animal reservoirs. Felid species and certain primates
serve as the principal reservoir hosts for the zoonotic Brugia
pahangi.
Mosquito species belonging to the genera Mansonia and Aedes are
the usual vectors for Brugia spp. filariasis. In the case of
Wuchereria bancrofti, the transmission varies geographically and
involves a range of mosquito genera/species, including Aedes spp.,
Anopheles spp., Culex spp., Mansonia spp., and Coquillettida
juxtamansonia..
Causative Agents: Lymphatic filariasis (LF) is a disease caused by
filarial nematodes transmitted through mosquito bites, specifically
Wuchereria bancrofti, Brugia malayi, and B. timori. The majority,
around 90%, of LF cases are associated with W. bancrofti, which
is referred to as Bancroftian filariasis.
Life Cycle Brugia malayi
During a mosquito's blood meal, the introduction of third-stage
filarial larvae onto the human host's skin occurs, typically
facilitated by infected mosquitoes such as Mansonia spp. and
Aedes spp. These larvae penetrate the bite wound, maturing into
adults that predominantly inhabit the lymphatics. Although the
adult worms share similarities with those of Wuchereria bancrofti,
they are smaller in size. Female worms measure 43 to 55 mm in
length and 130 to 170 μm in width, while males measure 13 to 23
mm in length and 70 to 80 μm in width. The adult worms produce
sheathed microfilariae, measuring 177 to 230 μm in length and 5
to 7 μm in width, with a nocturnal periodicity (though B. malayi
may exhibit sub-periodic behavior in certain regions, and it's
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important to note that microfilariae are typically not produced in
B. pahangi infections).
[Image1.https://www.cdc.gov/dpdx/lymphaticfilariasis/modules/
B_malayi_LifeCycle_19.jpg]
These microfilariae migrate into the lymph and enter the
bloodstream, eventually reaching the peripheral blood. During a
subsequent blood meal, a mosquito ingests the microfilariae.
Following ingestion, the microfilariae shed their sheaths and
traverse the proventriculus and cardiac section of the midgut,
ultimately reaching the thoracic muscles. Within the muscles, the
microfilariae undergo development into first-stage larvae and
subsequently progress to third-stage larvae. These third-stage
larvae migrate through the hemocoel to the mosquito's proboscis,
making it possible to infect another human during the mosquito's
next blood meal.
Life Cycle of Wuchereria bancrofti
During a mosquito's blood meal, infected mosquitoes deposit third-
stage filarial larvae onto the skin of the human host, where they
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infiltrate the bite wound. These larvae mature into adults that
typically inhabit the lymphatic system. Female worms measure 80
to 100 mm in length and 0.24 to 0.30 mm in diameter, while males
measure around 40 mm by 1 mm. Adult worms generate sheathed
microfilariae, measuring 244 to 296 μm by7.5 to 10 μm, exhibiting
nocturnal periodicity, except for South Pacific microfilariae, which
lack marked periodicity. The microfilariae actively migrate
through the lymph and blood channels.
[Image2.https://www.cdc.gov/dpdx/lymphaticfilariasis/modules/
W_bancrofti_LifeCycle_lg.jpg]
During a mosquito's subsequent blood meal, it ingests the
microfilariae. After ingestion, some microfilariae shed their
sheaths and traverse the wall of the proventriculus and cardiac
portion of the mosquito's midgut, reaching the thoracic muscles.
Within the muscles, the microfilariae undergo development into
first-stage larvae and subsequently progress into third-stage
infective larvae. These infective larvae migrate through the
hemocoel to the mosquito's proboscis, enabling the infection of
another human when the mosquito takes its next blood meal.
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Worldwide Initiative for Eradicating Lymphatic Filariasis: An
Overview of Development and Present Status Scenario
Lymphatic filariasis (LF) is a preventable neglected tropical
disease (NTD) resulting from infection with filarial parasites,
namely Wuchereria bancrofti, Brugia malayi, or B. timori.
Mosquitoes of the Culex, Anopheles, Mansonia, and Aedes genera
transmit these parasites between individuals. The visible, chronic
clinical outcomes of lymphatic vessel impairment due to these
infections include lymphoedema and hydrocoele. The World
Health Organization (WHO) established the Global Programme to
Eliminate Lymphatic Filariasis (GPELF) with the goals of halting
infection transmission through mass drug administration (MDA)
of anthelminthics and addressing the suffering of affected
individuals through morbidity management and disability
prevention (MMDP). Since GPELF's inception, global infections
have decreased by 74%, with the current estimate indicating 51.4
million people are still affected.
The absence of a non-human reservoir for W. bancrofti and
minimal animal hosts for B. malayi implies that interrupting
transmission is achievable by reducing the microfilariae (Mf) stage
through mass drug administration (MDA). Advances in safe,
single-dose, two-drug treatments that effectively lower Mf levels
for an extended period, coupled with notable improvements in
diagnostic techniques, prompted the global advocacy for
eliminating lymphatic filariasis (LF) through MDA (CDC, 1993,
Molyneux et. al., 2002). This advocacy culminated in the pivotal
1997 World Health Assembly Resolution WHA50.29, which
called for the global elimination of LF as a public health concern.
Subsequently, in 2000, the World Health Organization, in
collaboration with various international agencies from both public
health and private sectors, established a global alliance (WHO,
2000) and initiated a worldwide campaign to eliminate LF by 2020
(Yamey, 2000).
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The primary objective of the Global Program to Eliminate
Lymphatic Filariasis (GPELF) is to disrupt the transmission cycle
of parasites between mosquitoes and humans, primarily through
MDA involving albendazole (ALB) in combination with either
ivermectin (IVR) or diethylcarbamazine citrate (DEC) (Ottesen
2000, WHO 1999, 2000). All 83 LF-afflicted countries have
committed to implementing their national elimination programs,
with 44 of them having initiated MDA by the end of 2006 (WHO,
2007).
Obstacles to MDA initiatives
Despite the advancements in initiating Mass Drug Administration
(MDA) programs, several challenges have emerged. Firstly,
several countries, even after 5–6 years of initiating MDA, have not
achieved national scale, facing significant difficulties in sustaining
MDA due to resource constraints (WHO, 2007). The limitations in
resources and the availability of rapid diagnostic tests have
impeded progress in mapping implementation units for MDA.
Operational challenges have arisen in delivering MDA in urban
areas. Secondly, the precise level and duration of treatments
needed for LF elimination in various endemic regions remain
uncertain (Michael et. al., 2006, 2007), making it challenging to
determine when to conclude ongoing MDA programs. Thirdly, a
major hurdle in achieving elimination targets within a reasonable
timeframe has been the difficulty in attaining the required high
drug coverage in endemic communities (Plaisier et. al., 2000).
Fourthly, there is a recent trend of integrating MDA for LF control
with programs targeting other neglected tropical diseases, such as
schistosomiasis, soil-transmitted helminthiasis, and onchocerciasis
(Hotez et. al., 2007; Molyneux et. al., 2004). While this integrated
approach is appealing for eliminating duplication of effort and
costs in programs with common activities, the differing objectives
and potential increased complexity in drug delivery raise
uncertainties about its impact on LF elimination. Finally, concerns
about the potential development of drug resistance by filarial
parasites under mass chemotherapeutic pressure raise questions
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about the efficacy of relying solely on MDA for successful LF
elimination (Michael et. al., 2004; Schwab et al., 2005).
Accomplishments
The expansion of mass drug administration (MDA) is no longer
seen as sustainable. Achieving the desired impact necessitates
multiple rounds of MDA with effective coverage (≥65% of the
total population). The World Health Organization (WHO) suggests
conducting sentinel and spot-checks community surveys, followed
by a transmission assessment survey (TAS), to assess the
effectiveness of MDA and determine if the infection level has
dropped below the designated threshold. TAS is reiterated twice
over a 4–6 year period post cessation of MDA (TAS2 and TAS3)
to confirm the absence of LF infection recurrence.
In 2020, the Global Programme to Eliminate Lymphatic Filariasis
(GPELF) established the following objectives for the new Road
Map on Neglected Tropical Diseases (NTD) spanning from 2021
to 2030:
1. Ensure that 58 out of the 80% of countries with endemic LF meet
the criteria for validating the elimination of lymphatic filariasis as
a public health concern. This entails sustaining infection rates
below specified thresholds for at least four years after concluding
Mass Drug Administration (MDA) and delivering essential care
packages in all regions with documented patients.
2. Ensure that all 72 endemic countries implement surveillance
activities post-MDA or post-validation to monitor and respond to
any potential resurgence of the disease.
3. Achieve a reduction to zero in the total population requiring
Mass Drug Administration (MDA), reflecting successful progress
towards eliminating LF as a public health issue.
Discussions and Conclusion
Lymphatic filariasis (LF) is a widespread infectious disease caused
by filarial parasites transmitted through mosquitoes, affecting
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around 128 million people across 78 endemic countries. It
primarily occurs in tropical regions, with significant prevalence in
Southern and Southeast Asia and tropical Africa. Efforts to
eliminate LF began in the 1950s, with initiatives like Mass Drug
Administration (MDA) and vector control. Global commitments,
such as the London Declaration in 2012, reinforced the goal of
eliminating LF as a public health concern by 2020. Wuchereria
bancrofti is the most widespread parasite among the three causing
LF. Transmission occurs through various mosquito species, and
the disease can lead to severe consequences, including disabilities
and disfigurement. Mass treatment using anti-helminthic drugs is a
key strategy for halting infection spread.
Epidemiologically, LF affects over 120 million people globally,
with India, Africa, Southeast Asia, the Pacific, and the Americas
being the most affected regions. Socially, LF has profound
impacts, causing individuals to face stigma, dropout from school,
and experience difficulties in marriage and employment. The
burden of LF extends beyond physical health to encompass
psychological, economic, and sociological dimensions.
The disease predominantly affects regions with specific
environmental conditions conducive to transmission, including
poor sanitation and limited healthcare access. LF poses a
significant economic burden due to treatment costs, lost
productivity, and social stigma. Efforts to control LF involve mass
drug administration, mosquito control, and improved sanitation.
The physical burden of LF includes lymphedema, hydrocele,
recurrent acute attacks, disfigurement, and functional impairments.
The disease's economic impact extends to treatment costs, lost
productivity, and social stigma, contributing to a cycle of poverty
for affected individuals and communities.
The sociological burden involves stigma, social exclusion, impact
on relationships, gender dynamics, educational barriers, and
community resilience. Addressing the sociological burden requires
community awareness, inclusivity, and support systems.
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Lymphatic filariasis is caused by three closely related nematode
worms: Wuchereria bancrofti, Brugia malayi, and B. timori. The
transmission dynamics involve mosquito vectors and humans, with
specific mosquito species transmitting each parasite.
The Global Programme to Eliminate Lymphatic Filariasis
(GPELF) aims to halt transmission through mass drug
administration (MDA) and manage morbidity. Challenges to MDA
initiatives include resource constraints, uncertainty about treatment
duration, and the integration of LF control with other neglected
tropical diseases. Despite challenges, progress has been made, and
the GPELF has set objectives for the new roadmap (2021-2030),
focusing on validating elimination, surveillance, and reducing the
need for MDA.
In conclusion, addressing the multifaceted challenges of LF
requires a comprehensive approach involving medical
interventions, community engagement, and global collaboration to
eliminate the disease of public health impact by 2023.
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and surveillance. PLoS Negl Trop Dis , 7:e2416.
24. Ottesen EA. (2000). The Global Programme to Eliminate
Lymphatic Filariasis. Trop. Med. Int. Health 5:591–94.
25. Plaisier AP, Stolk WA, van Oortmarssen GJ, Habbema JD.
(2000). Effectiveness of annual ivermectin treatment for
Wuchereria bancrofti infection. Parasitol. Today 16:298–302.
26. Ramaiah, K. D., Das, P. K., Michael, E., & Guyatt, H. L.
(2000). The economic burden of lymphatic filariasis in
India. Parasitology today, 16(6), 251-253.
27. Suma, T. K., Shenoy, R. K. & Kumaraswami, V. (2003). A
qualitative study of the perceptions, practices and socio—
psychological suffering related to chronic brugian filariasis in
Kerala, southern India. Annals of Tropical Medicine and
Parasitology, 97, 839–845. [Taylor & Francis]
28. Schwab AE, Boakye DA, Kyelem D, Prichard RK. (2005).
Detection of benzimidazole resistance-associated mutations in the
filarial nematode Wuchereria bancrofti and evidence for selection
by albendazole and ivermectin combination treatment. Am. J.
Trop. Med. Hyg. 73:234–38
29. Taylor MJ, Hoerauf A, Bockarie M (2010). Lymphatic
filariasis and onchocerciasis. Lancet, 376:1175–1185.
30. WHO. (2007). Global programme to eliminate lymphatic
filariasis. Wkly. Epidemiol. Rec. 82:361–80.
31. World Health Organization. (2001). Lymphatic
filariasis. Weekly Epidemiological Record= Relevé
épidémiologique hebdomadaire, 76(20), 149-154.
32. WHO. (2000). Eliminate Filariasis: Attack Poverty. The
Global Alliance to Eliminate Lymphatic Filariasis. Proc.1st Meet.,
Santiago de Compostela, Spain. 4–5 May.
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Doc.WHO/CDS/CPE/CEE/2000.5. Geneva: World Health Organ.
41 pp.
33. WHO. (1999). Building Partnerships for Lymphatic Filariasis.
Strategic Plan. Sept. Doc. WHO/FIL/99.198. Geneva: World
Health Organ. 64 pp.
34. WHO, (2008a). World malaria report. In
WHO/HTM/GMP/2008.1 (Geneva, http://
www.who.int/malaria/wmr2008/malaria2008.pdf), 215 p.
35. Wynd, S., Melrose, W. D., Durrheim, D. N., Carron, J., &
Gyapong, M. (2007). Understanding the community impact of
lymphatic filariasis: a review of the sociocultural
literature. Bulletin of the World Health Organization, 85, 493-498.
36. Yamey G. (2000). Global alliance launches plan to eliminate
lymphatic filariasis. Br. Med. J. 320:269.
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Chapter-8
THE ORCHESTRA OF HELMINTHS: THE INTERPLAY
OF HELMINTH PARASITES BETWEEN HUMANS AND
ANIMALS
Anil Kumar1 and Pradeep Kumar2
1Assistant Professor, Department of Zoology, Baba Raghav Das
Post Graduate College, Deoria- 274001
2Department of Zoology, School of Life Sciences, Babasaheb
Bhimrao Ambedkar University- Lucknow, Uttar Pradesh, India,
226025
Corresponding Author Email: kuanil143@gmail.com
Abstract
Parasitism is one of the most successful modes of life displayed by
living organisms. Virtually all non-parasitic animals harbour at
least one parasite species. Helminth parasites have long been
captivated the attention of scientists, clinicians and researchers due
to their intricate life cycles, impact on both animals and humans
and the challenges they pose to public health and veterinary
medicine. These encompass various species of nematodes
(roundworms), cestodes (tapeworms) and trematodes (flukes) and
they play a significant role in the intricate web of host-parasite
interactions that spans the animal kingdom. They have the
remarkable ability to exploit a wide range of hosts, often moving
between animals and humans, thereby blurring the lines between
zoonotic diseases and parasitic infections primarily afflicting one
host group. They display remarkable adaptations that enable their
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survival and reproduction within their host environments. Some
species exhibit complex life cycles involving multiple host species,
which allow them to exploit different ecological niches. They have
evolved diverse reproductive strategies with some producing vast
numbers of eggs or larvae to ensure transmission, while others
invest more in individual offspring. These adaptations not only
enhance their chances of survival but also contribute to their
capacity to exploit a wide range of host species. Between 75,000
and 300,000 species of helminths are known to parasitize
vertebrates, including approximately 50 to 60 different species of
helminth parasites parasitizing human beings. Ascariasis, filariasis,
colitis, ancylostomiasis, taeniasis etc. are some of the most
important diseases caused by various heminth parasites in man.
The management of helminth parasites requires a multifaceted
strategy that encompasses both preventive measures and medical
interventions. Improved sanitation, hygiene and public awareness
campaigns are vital for reducing transmission, particularly for
infections spread through contaminated water and soil. Mass drug
administration, employing anthelmintic drugs like mebendazole,
albendazole, and praziquantel, is a pivotal element in the control of
helminth diseases. Development of effective vaccines for certain
infections and regular surveillance to monitor infection rates are
essential components of control programmes. Environmental
management, involving vector control and intermediate host
management, plays a crucial role in disease prevention.
Deworming domestic animals is significant in areas where
zoonotic helminths pose a risk to human health. Ongoing research,
drug development, and international collaboration are imperative
for refining control strategies and mitigating the impact of these
parasites on global health.
Keywords: Parasitism, Helminths, Trematodes, Cestodes
INTRODUCTION
The term “helminth” is derived from a Greek word signifying
“worm” (Soulsby, 1986). Helminths encompass a wide array of
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worms, including those that live freely and those that are parasitic
(Brusca & Brusca, 2003). Helminth parasites are a major public
health problem worldwide, and animals play a significant role in
their transmission and maintenance. There is a growing body of
scientific evidence that supports the importance of the animal-
human interface in helminth transmission. For example, studies
have shown that children who live in close proximity to livestock
are at increased risk for infection with certain helminth parasites,
such as ascariasis and hookworm. Animals can play a role in the
spread of emerging helminth infections, such as cystic
echinococcosis and zoonotic trematodiasis. Certain animals serve
as reservoirs for helminth parasites, meaning that they can harbor
the parasites without showing any signs of disease. This is the case
with many zoonotic helminth parasites, such as Echinococcus
granulosus and Taenia solium.
These parasites can be transmitted to humans through the ingestion
of contaminated food or water, or through direct contact with
infected animals or their faeces. In addition to their role in
transmission, animals can also play a role in the maintenance of
helminth parasites in the environment. For example, the snails that
serve as intermediate hosts for many trematode parasites can live
in close proximity to livestock. This can lead to increased
transmission of trematode infections to both humans and animals.
There many other species of helminths which are free living and
not requiring any host complete their life cycle. They are found in
a variety of environments, including soil, freshwater, and marine
ecosystems. Free-living helminths play an important role in the
decomposition of organic matter and in the food chain. Free-living
helminths are important for a number of reasons.
They help to decompose organic matter in the soil, which improves
soil fertility. They are also a food source for many other animals,
such as birds, fish, and frogs. Free-living helminths are also used
in a variety of research applications, including studies of genetics,
development, and disease. For example, Caenorhabditis elegans
(C. elegans) a small, transparent nematode worm that is widely
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used as a model organism in biology research. It is a relatively
simple organism with only 959 somatic cells, but it shares many
fundamental biological features with other animals, including
humans. C. elegans is easy to grow and maintain in the laboratory
and its short life cycle (approximately 3 days) makes it ideal for
genetic studies. Caenorhabditis elegans, are used in a variety of
research applications, including studies of genetics, development
and disease (Culetto & Sattelle, 2000). It is used as model animal
for human diseases. They can introduce mutations into C. elegans
that are known to cause diseases in humans, and then study the
effects of these mutations on the worm's development, behaviour,
and physiology.
Free-living helminths are generally not harmful to humans.
However, some species can cause infections in humans, especially
in people with weakened immune systems. For example, the
nematode Strongyloides stercoralis can cause strongyloidiasis, a
chronic infection that can be difficult to treat (Greaves et al., 2013).
The majority of parasitic worms fall within two phyla viz;
Aschelminthes (or Nemathelminthes) or roundworms and
Platyhelminthes or flatworms. Aschelminthes include worms
having long and cylindrical body organization whereas include
worms having a flat body plan. Platyhelminthes include planarians
(Turbellaria), usually free living; flukes (Trematoda), usually
endoparasites of and tapeworms (Cestoda), endoparasites of
vertebrates, with segmented ribbon like body (Craig & Faust,
1970).
These are characterized by an outer protective layer referred to as
a cuticle or tegument. This tegument can vary in toughness and
serves to shield the worm from challenges posed by the defensive
mechanisms of host (Brusca & Brusca, 2003; Thompson & Geary,
1995). It may possess structures like spines, hooks, cutting plates
or stylets used for attachment and/ or facilitating penetration to-or
into the host’s body. Some species feature acetabula or suckers for
attachment, while others have lytic glands near the mouth, which
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secrete enzymes for digesting host tissue or aiding in migration.
Most trematodes are hermaphroditic, while schistosomes are an
exception with separate sexes (Cox, 2000). Tapeworm segments
house both male and female reproductive organs, while nematodes
have distinct sexes (Morand et al., 2006). These worms may
produce larvae, but most commonly, they generate eggs that exit
the host through faecal matter. Some worms inhabiting the
circulatory system produce larvae that are ingested by blood-
feeding arthropods and subsequently transmitted to other hosts
through bites from infected vectors. Helminth life cycles vary from
direct transmission, where eggs are excreted in faeces and ingested
by a host, to intricate life cycles that involve one or more
intermediate hosts (Parker et al.,2015). Helminth life cycles vary
from direct transmission, where eggs are excreted in faeces and
ingested by a host, to intricate life cycles that involve one or more
intermediate hosts (Benesh et al.,2021).
Some species exhibit complex life cycles involving multiple host
species, which allow them to exploit different ecological niches.
They have evolved diverse reproductive strategies with some
producing vast numbers of eggs or larvae to ensure transmission,
while others invest more in individual offspring. These adaptations
not only enhance their chances of survival but also contribute to
their capacity to exploit a wide range of host species (Brusca and
Brusca., 2000).
Hosts and parasites undergo coevolution and their interactions
often lead to transformations (Hoberg et al., 1997; Thompson.,
2014). In situations where a parasite exclusively associates with a
host, the dynamics of this relationship are driven by natural
selection towards greater tolerance and in some cases, even
mutualism (Nelson et al., 2017). This occurs because the parasite
benefits from the host's longer lifespan, allowing for an extended
period of reproduction (Canestrari et al., 2014). Conversely, when
parasites are in competition with one another, natural selection
favours the parasite that reproduces most rapidly, leading to an
escalation in virulence (Oalno et al., 2011). Consequently, host-
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parasite coevolution can manifest in diverse ways. Between 75,000
and 300,000 species of helminths are known to parasitize
vertebrates, including approximately 50 to 60 different species of
helminth parasites parasitizing human beings (Cox, 2000).
Ascariasis, filariasis, colitis, ancylostomiasis, taeniasis etc. are
some of the most important diseases caused by various heminth
parasites in man.
The management of human helminth parasites necessitates a
multifaceted strategy that encompasses both preventive measures
and medical interventions (Craig & Faust, 1970). Improved
sanitation, hygiene, and public awareness campaigns are vital for
reducing transmission, particularly for infections spread through
contaminated water and soil. Mass drug administration, employing
anthelmintic drugs like mebendazole, albendazole, and
praziquantel, is a pivotal element in the control of helminth
diseases. Development of effective vaccines for certain infections
and regular surveillance to monitor infection rates are essential
components of control programmes. Environmental management,
involving vector control and intermediate host management, plays
a crucial role in disease prevention. Deworming domestic animals
is significant in areas where zoonotic helminths pose a risk to
human health. Ongoing research, drug development, and
international collaboration are imperative for refining control
strategies and mitigating the impact of these parasites on global
health (WHO., 2019; Taylor et al., 2013).
Helminths in human and animal health
Cestodes (tapeworms), trematodes (flukes) and nematodes
(roundworms) are the primary classes of helminths that infect
humans and various animal species. These parasites can lead to a
spectrum of diseases, causing varying degrees of morbidity and
mortality in affected individuals (Narahari et al.,2016).In humans,
helminth infections are associated with conditions such as
ascariasis, trichuriasis, hookworm disease, schistosomiasis and
Taenia (taeniasis) infections. These parasitic diseases often result
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from the ingestion or penetration of infective helminth stages (Keo
et al., 2015). The severity of these infections can range from mild
discomfort to severe pathology, depending on factors such as the
parasite load, the host's immune response, and the specific parasite
species involved (Wang, 2022). Helminths pose a significant
challenge to both domestic and wild species (Wells et al., 2018).
Livestock, for example, are susceptible to various nematode
infections that impact their growth, productivity, and overall
health. Wildlife can also be affected, with potential consequences
for ecological balance (Charlier et al., 2009). In some cases,
zoonotic transmission, where parasites move between animals and
humans, further complicates the picture.
Understanding the complex life cycles of helminths and their
interactions with both human and animal hosts is vital for the
development of effective control and management strategies.
These strategies include mass drug administration, vaccination
research, sanitation improvements, and vector control measures.
Ongoing research in this field aims to mitigate the impact of
helminth parasites on the health and well-being of humans and
animals while also considering the broader ecological implications
(Crompton, 2003).
Trematodes
Trematodes are called as flukes and are placed under the class
Trematoda of phylum Platyhelminthes. They are characterized by
their flat, leaf-like or oval-shaped bodies and they are known to
infect a wide range of vertebrate hosts, including humans. They are
responsible for causing various diseases in humans and other
animals, and their life cycles are often complex, involving multiple
hosts. Their body is dorsoventrally flattened, and they lack a
respiratory or circulatory system. They typically possess a highly
specialized sucker or holdfast organ called as acetabulum that
helps the parasites attach to the host's tissues. They comprise
several families, such as Schistosomatidae, Fasciolidae, and
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Paramphistomatidae, based on their morphological and biological
characteristics.
Their life cycle usually involves multiple stages, including egg and
multiple larval phases, like miracidium, sporocyst, cercaria, and
metacercaria (Galaktionov & Dobrovolskij, 2013). These stages
often require different host species to complete their life cycle.
Eggs are excreted from the host's body through faeces or urine.
Once a suitable aquatic environment is available, the embryos
hatch into miracidia, which are ciliated, free-swimming larvae.
Generally, the humans serve as the primary host in which the adult
worm lives and feeds. Parts of the larval phases complete in
gastropod molluscs (e.g; Lymnaea, Planorbis, Succinia, Bullinus,
Practicolella). With the help of cilia present on their body surface,
they swim around when they come in contact with intermediate
hosts (i.e; gastropod molluscs), they bore into the soft tissue and
move into their body where certain parts of the larval phases
complete. These miracidia contain germ cells which multiply
forming collections of cells, the germ balls which ultimately give
rise to the new larval stage, the sporocysts. Sporocysts give rise to
cercariae, which are the next larval stage. Cercariae exit the snail
host and swim in the water, seeking to penetrate their definitive
host (or principal host). Cercariae are often tailed larvae which
swim in the water and encyst and in a protective cyst producing
metacercariae. These metacercariae finally reach to the primary
host through their ingestion either with the secondary host or
without it (Fried, 1997; Poulin & Cribb, 2002).
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Figure: 1. Illustration showing the life cycle of helminth parasite
Trematode Parasites in Humans
1. Schistosoma
Schistosoma parasites cause schistosomiasis, a prevalent tropical
disease. These parasites infect humans when cercariae in
contaminated water penetrate the skin. Once inside the body, they
develop into adult worms, which live in the blood vessels and lay
eggs. This can lead to chronic inflammation, tissue damage and
organ dysfunction (He & Ramaswamy, 2005).
The life cycle of Schistosoma involves two hosts: a definitive host
(human) and an intermediate host (snails). The definitive host
becomes infected by contact with contaminated water that contains
cercariae, the infective stage of the parasite. The cercariae
penetrate the skin and migrate to the liver, where they develop into
mature worms. The adult worms mate and produce eggs, which are
passed in the urine or faeces of the definitive host.
The eggs hatch in water and release miracidia which are free-
swimming larvae. The miracidia penetrate snails and develop into
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sporocysts which produce cercariae. The cercariae are released
from the snails and swim in the water, where they can infect the
definitive host.
painful urination, haematuria (blood in the urine), liver
enlargement, splenomegaly, ascites, fatigue, weakness, weight loss
Figure: 1. Showing infection cycle of Schistosoma mansoni
Infection can cause a variety of clinical manifestations depending
on the species of parasite and the severity of infection. Common
symptoms include, abdominal pain, diarrhea, bloody stools
In severe cases, schistosomiasis can lead to life-threatening
complications, such as liver failure, kidney failure, and portal
hypertension.
Schistosomiasis is diagnosed by the detection of Schistosoma eggs
in the urine or faeces. The eggs can be identified using a light
microscope or by a variety of immunological tests.
Treatment for schistosomiasis involves the use of praziquantel, a
drug that is effective against all species of Schistosoma.
Praziquantel is administered in a single oral dose and is generally
well-tolerated.
The best way to prevent schistosomiasis is to avoid contact with
contaminated water. This can be done by boiling or filtering
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drinking water, avoiding swimming or wading in contaminated
water and wearing protective footwear when walking in areas
where schistosomiasis is common. The disease affects over 240
million people worldwide, making it the second most common
neglected tropical disease after malaria (World Health
Organization, 2023).There are seven known species of
Schistosoma that infect humans. S. haematobium, S. mansoni,S.
japonicum, S. mekongi, S. intercalatum, S. guineensis: S. mattheei
are few of the examples.
2. Clonorchis
They exhibit a flattened, lance-shaped morphology, ranging from
10 to 25 millimeters in length and 3 to 5 millimeters in width. Their
anterior end features a small oral sucker for attachment and
feeding, while a larger ventral sucker is located at the mid-body,
aiding in locomotion and attachment. Their life cycle involves
three hosts: a freshwater snail, a freshwater fish and a definitive
mammal host, primarily humans. These parasites inhabit the liver
and bile ducts of their vertebrate hosts, causing a range of health
complications if left untreated.
Freshwater snails of the genus Parafossarulus serve as the initial
host for Clonorchis. The adult flukes release eggs into the faeces
of their definitive host, which are then passed into water bodies.
Once ingested by snails, the eggs hatch into miracidia, which
undergo asexual multiplication within the snail's body.
After reaching a certain developmental stage, the miracidia are
released from the snail and transform into cercariae. These
cercariae actively seek out and penetrate freshwater fish of the
families Cyprinidae and Cobitidae. Encysting within the fish
muscles, they mature into metacercariae.
Humans serve as the definitive host of Clonorchis and become
infected with it when they consume raw or undercooked freshwater
fish harbouring the metacercariae. Upon ingestion, the
metacercariae excyst and migrate to the liver, where they mature
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into adult flukes. These adult flukes reside in the bile ducts, feeding
on bile and potentially causing a range of health issues.
The presence of Clonorchis flukes in the liver and bile ducts can
lead to a variety of pathological manifestations, collectively known
as clonorchiasis. Symptoms commonly associated with
clonorchiasis include jaundice, abdominal pain, nausea,diarrhoea,
persistent tiredness andweight loss. In severe cases, the chronic
inflammation caused by the flukes can lead to more serious
complications, such asiver cirrhosis,cholangiocarcinoma and
hepatic carcinoma.
Diagnosis of clonorchiasis primarily relies on microscopic
examination of stool samples to detect the presence of eggs. Blood
tests may be employed to assess liver function and identify
antibody markers specific for Clonorchis infection. Imaging
modalities such as ultrasound and CT scans can also provide
valuable insights into liver pathology.
Treatment typically involves the administration of anthelmintic
drugs, such as praziquantel or albendazole. These medications
effectively target and eliminate the adult flukes, alleviating
symptoms and preventing further complications.
The most effective strategy to prevent clonorchiasis is to avoid
consuming raw or undercooked freshwater fish from endemic
areas. Thorough cooking of fish to an internal temperature of
145°F (63°C) or freezing it to -4°F (-20°C) for at least 24 hours
effectively destroys the metacercariae, rendering the fish safe for
consumption(Na & Hong, 2020; Min, 1984).
3. Fasciola
Two species viz; Fasciola hepatica and Fasciola gigantica, within
this genus are well-known for infecting mammals including
humans. Both species have complex life cycles that involve
multiple hosts.
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a) F. hepatica (Common liver fluke): This species primarily
infects sheep, cattles and other mammals, including humans. This
species is distributed worldwide. Adults are leaf-shaped and can
reach lengths of up to 3 cm. The body has two suckers, oral and
ventral which are used for attachment to the host's liver. Eggs are
released in the host's liver and pass out of the body through the
faeces. They hatch into larvae (miracidia) in water. The miracidia
infect a snail host, where they go through several developmental
stages. Cercariae are released from the snail and encyst on
vegetation as metacercariae. Mammals become infected by
ingesting contaminated water or plants. Once inside the host, the
metacercariae excyst in the small intestine and migrate to the liver,
where they mature into adult flukes.
b) F. gigantica (Giant liver fluke): Fasciola gigantica infects
cattles, water buffaloes and other mammals. They are found mainly
in Africa and parts of Asia. Morphologically, they are similar to F.
hepatica, but generally larger in size. Adults can reach lengths of
5 cm or more. The life cycle is similar to that of F. hepatica,
involving a snail intermediate host and encysted metacercariae on
vegetation. Infection occurs when mammals ingest contaminated
water or plants.
Both species of Fasciola can cause a disease known as fascioliasis
in humans and animals. The symptoms in humans may include
abdominal pain, fever, and liver dysfunction. The prevention and
control of fascioliasis involve measures such as improving water
quality, avoiding the consumption of raw watercress and other
aquatic plants, and treating infected animals (Masake et al., 1978;
Lalor et al., 2021).
4. Paragonimus species
Paragonimus lung flukes are acquired through the consumption of
undercooked or raw freshwater crustaceans. These parasites
migrate to the lungs, causing symptoms resembling pneumonia
(Yokogawa, 1965; Blair, 2022).
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5. Opisthorchis
These flukes are responsible for opisthorchiasis, a parasitic disease
that predominantly occurs in regions of Southeast Asia and Eastern
Europe. There are five species within the genus Opisthorchis.
a) Opisthorchis viverrini(Southeast Asian liver fluke): It is the
most prevalent and medically important species of Opisthorchis. It
is endemic in parts of Southeast Asia, including Thailand, Laos,
Cambodia and Vietnam. Humans acquire the infection by
consuming raw or undercooked freshwater fish harbouring the
infectious metacercariae stage of the parasite. Adult O. viverrini
flukes reside in the bile ducts of the liver, where they produce eggs
that are shed in the host's faeces. These eggs can contaminate water
sources and are ingested by freshwater snails, serving as
intermediate hosts. Within the snail, the eggs undergo complex
developmental stages, eventually producing cercariae, the
infective form of the parasite. Cercariae emerge from the snails and
encyst in various species of freshwater fish, primarily cyprinids
(carps). When humans or other mammals consume raw or
undercooked fish containing the encysted metacercariae, the
parasites excyst and migrate to the bile ducts of the definitive host,
where they mature into adult flukes. Opisthorchiasis caused by O.
viverrini infection can manifest in various forms, ranging from
asymptomatic to severe. Acute symptoms, often seen in initial
infections, may include abdominal pain, diarrhea, and jaundice.
Chronic infections, which can persist for decades, can lead to more
serious complications, including cholangitis (inflammation of the
bile ducts), cholecystitis (inflammation of the gallbladder), and
cholangiocarcinoma (Poirier, 1886).
b) Opisthorchis felineus (European liver fluke): This species is
found primarily in parts of Europe, including Italy, Germany,
Belarus, Russia, Kazakhstan and Ukraine. Similar to O. viverrini,
it infects cats, dogs and various other fish-eating mammals.
Humans can also be infected through consumption of raw or
undercooked freshwater fish containing the infectious
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metacercariae (Rivolta, 1884).The life cycle of O. felineus closely
resembles that of O. viverrini, involving freshwater snails as
intermediate hosts and freshwater fish as definitive hosts. The
parasite's distribution and host range differ, with O. felineus being
more prevalent in Europe and infecting a wider range of
mammals.Opisthorchiasis caused by O. felineus infection presents
with symptoms similar to those caused by O. viverrini, including
abdominal pain, diarrhoea, and jaundice. However, O. felineus
infections may additionally cause fever, facial swelling, swollen
lymph glands, sore joints, and rash. Chronic infections can also
involve the pancreatic ducts, leading to pancreatitis.
c) Opisthorchis tenuicollis: Opisthorchis tenuicollis is primarily
found in Southeast Asia, with a distribution similar to that of O.
viverrini. It primarily infects cats and dogs, but humans can also be
infected through consumption of raw or undercooked freshwater
fish containing the infectious metacercariae. The life cycle of O.
tenuicollis mirrors that of O. viverrini and O. felineus, involving
freshwater snails as intermediate hosts and freshwater fish as
definitive hosts. The parasite's distribution and host range are more
restricted, with O. tenuicollis being primarily found in Southeast
Asia and infecting cats and dogs more frequently than humans.
Opisthorchiasis caused by O. tenuicollis infection presents with
symptoms similar to those caused by O. viverrini and O. felineus,
including abdominal pain, diarrhea, and jaundice (Dubois, 1929).
d) Opisthorchis tonkae: Opisthorchis tonkae is primarily found
in China, with a distribution similar to that of O. viverrini and O.
tenuicollis. It primarily infects cats and dogs, but humans can also
be infected through consumption of raw or undercooked freshwater
fish containing the infectious metacercariae. The life cycle of O.
tonkae closely resembles that of O. viverrini, O. felineus, and O.
tenuicollis, involving freshwater snails as intermediate hosts and
freshwater fish as definitive hosts. The parasite's distribution and
host range are more restricted, with O. tonkae being primarily
found in China and infecting cats and dogs more frequently than
humans. Opisthorchiasis caused by O. tonkae infection presents
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with symptoms similar to those caused by O. viverrini, O. felineus,
and O. tenuicollis, including abdominal pain, diarrhoea, and
jaundice (Faust, 1927)
e) Opisthorchis chabaudi: Opisthorchis chabaudi is another
species of Opisthorchis found in Southeast Asia, with a distribution
similar to that of O. viverrini, O. tenuicollis and O. tonkae. It
primarily infects cats and dogs, but humans can also be infected
through consumption of raw or undercooked freshwater fish
containing the infectious metacercariae. The life cycle of O.
chabaudi closely resembles that of other Opisthorchis species,
involving freshwater snails as intermediate hosts and freshwater
fish as definitive hosts. The parasite's distribution and host range
are more restricted, with O. chabaudi being primarily found in
Southeast Asia and infecting cats and dogs more frequently than
humans.Opisthorchiasis caused by O. chabaudi infection presents
with symptoms similar to those caused by other Opisthorchis
species, including abdominal pain, diarrhoea and jaundice
(Bourgat & Kulo, 1977).
Cestodes (Tapeworms)
Tapeworms, such as Taenia solium and Taenia saginata (beef and
pork tapeworms), Diphyllobothrium latum (fish tapeworm), and
Echinococcus species, are parasitic flatworms belonging to the
class Cestoda of phylum Platyhelminthes. Their life cycle
generally involves a definitive host (usually a human) and an
intermediate host (often livestock or fish), where they adapt to their
parasitic lifestyle. In the definitive host, they attach to the intestine,
growing to several meters in length, causing diseases like taeniasis
(intestinal infection). Their eggs or larvae are excreted in feces,
contaminating the environment. In intermediate hosts, larval
stages form cysts, causing diseases like cysticercosis and
diphyllobothriasis. Echinococcus species may cause cystic
echinococcosis or alveolar echinococcosis, forming invasive cysts
in vital organs. Preventative measures include proper cooking and
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hygiene, while treatment involves medications to eradicate the
parasites or surgical removal of cysts in severe cases.
These flatworms exhibit a remarkable adaptation for a parasitic
lifestyle, characterized by their elongated bodies that consist of
segments called proglottids. Echinococcus tapeworms exhibit the
unique adaptation of producing invasive cysts, which can infiltrate
and damage vital organs in their host.
To prevent infection, it is crucial to practice proper cooking of meat
and maintain good hygiene to avoid contamination. Treatment
typically involves medication to eliminate the parasites or surgical
removal of cysts, especially in severe cases where invasive cysts
are formed. These parasitic flatworms exemplify the fascinating
coexistence and adaptations that occur within complex host-
parasite relationships.
1. Taenia
Genus Taenia belongs to the order Cyclophyllidea. These all are
parasitic tapeworms that primarily infect the intestines of
mammals, including humans, cattle, pigs and other animals.
Taenia species are known for their long, ribbon-like morphology,
with some species reaching up to 10 meters in length. They possess
a complex life cycle that involves two hosts: a definitive host,
where the adult worm resides, and an intermediate host, where the
larval stage develops.
They typically cause infection through the consumption of raw or
undercooked meat containing the infectious larval stage, known as
cysticerci. Upon ingestion, the cysticerci excyst and mature into
adult tapeworms in the definitive host's intestines. Adult
tapeworms attach to the intestinal wall and absorb nutrients from
their host. They produce proglottids, segments that contain mature
eggs, which are shed in the host's feces. The cycle continues when
an intermediate host ingests these eggs, perpetuating the parasite's
life cycle.
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Taenia infections can cause a range of symptoms, including
abdominal discomfort, diarrhea and weight loss. In some cases, the
tapeworm may migrate to other parts of the body, causing
complications such as cysticercosis. Prevention of Taenia infection
primarily involves thorough cooking of meat to ensure the
destruction of cysticerci. Proper sanitation practices, including
adequate disposal of animal waste, can also help control the spread
of these tapeworms (Ito et al., 2003; Gracia et al., 2003; Gebrie &
Engdaw, 2015; Gonzales et al., 2016; Konyaev et al., 2017).
Figure: 3. Showing life cycle of Taenia solium
a) Taenia saginata (Beef Tapeworm): It is the most prevalent
species of Taenia, primarily found in regions with high beef
consumption. The adult worm can reach up to 10 meters in length
and resides in the small intestine of its definitive host, typically
humans. Infection occurs through ingestion of raw or undercooked
beef containing cysticerci, the larval stage of the parasite.
b) Taenia solium (Pork Tapeworm): It is less common but
more severe than T. saginata. It is primarily found in regions with
high pork consumption and poor sanitation practices. Like T.
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saginata, infection occurs through ingestion of raw or undercooked
pork containing cysticerci.
c) Taenia asiatica (Asian Tapeworm): It is primarily found in
Southeast Asia. It closely resembles T. saginata in morphology and
life cycle, with cattle serving as the intermediate host and humans
as the definitive host. Infection occurs through consumption of raw
or undercooked beef containing cysticerci.
d) Taenia crassicollis (Cattle Tapeworm): It infects cattle and
other ruminants. It is less common in humans but can cause
infection through accidental ingestion of infected cattle tissues.
Unlike T. saginata and T. solium, T. crassicollis does not form
cysticerci in humans and is considered a non-pathogenic parasite.
e) Taenia hydatigena (Echinococcal Tapeworm): It is
primarily found in sheep, cattle, and other mammals. It can cause
severe infection in humans, known as cystic echinococcosis or
hydatid disease, through ingestion of infected animal tissues or dog
faeces. The adult worm is relatively small, reaching up to 5 meters
in length.
f) Taenia tenella (Rabbit Tapeworm): It is primarily found in
Europe. It infects rabbits (order Lagomorpha) and can cause
infection in humans through accidental ingestion of rabbit faeces.
The adult worm is relatively small, reaching up to 2 meters in
length.
g) Taenia pisiformis (Dog Tapeworm): Commonly found in
dogs and cats (order Carnivora), T. pisiformis can cause infection
in humans, typically children, through accidental ingestion of
infected dog or cat faeces. The adult worm is relatively large,
reaching up to 10 meters in length.
h) Taenia ovis (Sheep Tapeworm): Primarily infects sheep and
other ruminants (order Atriodactyla), T. ovis can cause infection in
humans through accidental ingestion of infected sheep tissues. The
adult worm is relatively small, reaching up to 5 meters in length.
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i) Taenia cervi (Deer Tapeworm): Primarily found in deer and
other cervids (order Atriodactyla), T. cervi can cause infection in
humans through accidental ingestion of infected deer meat. The
adult worm is relatively small, reaching up to 5 meters in length.
j) Taenia rileyi(Lion Tapeworm): Primarily found in lions and
other felids (order Carnivora), T. rileyi can cause infection in
humans through accidental ingestion of infected lion or cat meat.
The adult worm is relatively large, reaching up to 10 meters in
length.
k) Taenia krabbei (Elephant Tapeworm): Primarily found in
elephants (order Proboscidea), T. krabbei can cause infection in
humans through accidental ingestion of infected elephant faeces.
The adult worm is relatively small, reaching up to 5 meters in
length.
l) Taenia brahmi (Camel Tapeworm): Primarily found in
camels, T. brahmi can cause infection in humans through
accidental ingestion of infected camel meat. The adult worm is
relatively small, reaching up to 5 meters in length.
m) Taenia equinococcus (Equine Tapeworm): Primarily found
in horses and other equines, T. equinococcus can cause infection in
humans through accidental ingestion of infected equine faeces. The
adult worm is relatively small, reaching up to 5 meters in length.
n) Taenia serialis (Serial Tapeworm): Primarily found in
rodents, T. serialis can cause infection in humans through
accidental ingestion of infected rodent faeces. The adult worm is
relatively small, reaching up to 5 meters in length.
o) Taenia asiatica var. multilocularis (Asian Alveolar
Tapeworm): A rare but severe parasite, T. asiatica var.
multilocularis primarily infects foxes and can cause infection in
humans through accidental ingestion of infected fox feces. The
adult worm is relatively small, reaching up to 5 meters in length.
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p) Taenia saginata var. americana(American Beef
Tapeworm): A variant of T. saginata, primarily found in the
Americas, T. saginata var. americana is similar to the common
beef tapeworm but has some genetic differences.
q) Taenia saginata var. europaea (European Beef Tapeworm):
A variant of T. saginata, primarily found in Europe, T. saginata
var. europaea is similar to the common beef tapeworm but has
some genetic differences.
r) Taenia solium var. asiatica (Asian Pork Tapeworm): A
variant of T. solium, primarily found in Asia. T. solium var.
asiatica is similar to the common pork tapeworm but has some
genetic differences.
3. Diphyllobothrium
The genus Diphyllobothrium includes a large group of tapeworms
that are known to infect humans, fish-eating mammals and birds.
These tapeworms are known as broad tapeworms or fish
tapeworms because they are characterized by their wide,
segmented bodies. The largest species of Diphyllobothrium can
reach up to 10 meters (33 feet) in length (Scholz et al., 2009).
a) Diphyllobothrium latum:This is the most common species of
Diphyllobothrium that infects humans. It is found worldwide, but
it is most common in Scandinavia, Japan, and South America.
b) Diphyllobothrium nihonkaiense: This species is found in
Japan, South Korea, Eastern Russia and North America.
c) Diphyllobothrium dendriticum: This species is found in the
northern parts of the Northern Hemisphere.
d) Diphyllobothrium pacificum: This species is found in
Argentina, Chile and Peru.
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These tapeworms have a complex life cycle that involves three
hosts: a definitive host, an intermediate host and a second
intermediate host. The definitive host is the final host in the life
cycle and it is usually a human, mammal or bird. The intermediate
host is a copepod crustacean and the second intermediate host is a
fish.When a definitive host eats an infected fish, the plerocercoid
larvae attach to the wall of the intestine and develop into adult
tapeworms. The adult tapeworms can live in the intestine for many
years and produce thousands of eggs, which are passed in the
faeces of the definitive host.Eggs are eaten by copepods and the
coracidia develop within the copepods. The copepods are then
eaten by fish, and the plerocercoid larvae develop within the fish.
They cause diphyllobothriasis which is manifested by a variety of
symptoms in humans, including abdominal pain, diarrhoea, weight
loss. They absorb vitamin B12 from the intestine, which can lead
to the development of megaloblastic anaemia (deficiency of
vitamin B12). Intestinal obstruction, inflammation in gall bladder
and pancreatitis are also the common symptoms of
diphyllobothriasis (Von Bonsdorff, 1977).
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4. Echinococcus
These tapeworms are typically found in the intestines of
carnivores, such as dogs, foxes, and wolves. The adult tapeworms
are relatively small, measuring only a few centimeters in length.
However, the larval stage of the tapeworm can form large cysts in
the internal organs of intermediate hosts, such as sheep, cattle, and
humans. These cysts can cause a variety of health problems,
including liver failure and death.
Echinococcus tapeworms are hermaphrodites, meaning that they
have both male and female reproductive organs. The adult
tapeworms produce eggs, which are passed out in the feces of the
definitive host. The eggs can then be ingested by an intermediate
host, where they hatch and release larvae. The larvae migrate to the
internal organs of the intermediate host, where they form cysts. The
cysts can grow over time and cause a variety of symptoms,
depending on the location of the cyst(Kern, 2010; Higuita et al.,
2016; Woolsey & Miller 2021). There are four main species of
Echinococcus tapeworms: E. granulosus, E. multilocularis, E.
vogeli and E. oligarthrus. Each species has a different definitive
host and intermediate host and each species can cause a different
form of echinococcosis.
a) E. granulosus: This is the most common species of
Echinococcus and is responsible for cystic echinococcosis (CE),
also known as hydatid disease. CE is the most common form of
echinococcosis in humans and is caused by ingestion of eggs from
the tapeworm's definitive host, which is usually a dog, but can also
be other canids such as foxes and wolves. The eggs are typically
shed in the feces of the definitive host and can contaminate food,
water, or soil. Humans become infected by accidentally ingesting
these eggs. Once ingested, the eggs hatch in the intestines and
release larvae, which migrate to various organs in the body, most
commonly the liver and lungs. The larvae form cysts in these
organs, which can slowly grow over time and cause a variety of
symptoms, depending on the location of the cyst.
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b) E. multilocularis: This species is responsible for alveolar
echinococcosis (AE), the most serious form of echinococcosis. AE
is a rare but potentially fatal disease that is caused by ingestion of
eggs from the tapeworm's definitive host, which is usually a fox,
but can also be other canids such as dogs and coyotes. The eggs are
typically shed in the feces of the definitive host and can
contaminate food, water, or soil. Humans become infected by
accidentally ingesting these eggs. Once ingested, the eggs hatch in
the intestines and release larvae, which migrate to the liver, where
they form cysts. The cysts in AE are different from those in CE in
that they are not fluid-filled and instead grow in an invasive,
infiltrative manner. This can lead to serious complications, such as
liver failure or death.
c) E. vogeli: This species is responsible for neotropical
echinococcosis, a rare form of echinococcosis that is found
primarily in Central and South America. Neotropical
echinococcosis is caused by ingestion of eggs from the tapeworm's
definitive host, which is usually a wild cat, such as the jaguar or
puma. The eggs are typically shed in the feces of the definitive host
and can contaminate food, water, or soil. Humans become infected
by accidentally ingesting these eggs. Once ingested, the eggs hatch
in the intestines and release larvae, which migrate to various organs
in the body, most commonly the liver. The larvae form cysts in
these organs, which can slowly grow over time and cause a variety
of symptoms, depending on the location of the cyst.
d) E. oligarthrus: This species is another rare cause of
neotropical echinococcosis. It is found primarily in Central and
South America and is caused by ingestion of eggs from the
tapeworm's definitive host, which is usually a rodent, such as the
agouti or paca. The eggs are typically shed in the faeces of the
definitive host and can contaminate food, water, or soil. Humans
become infected by accidentally ingesting these eggs. Once
ingested, the eggs hatch in the intestines and release larvae, which
migrate to the liver, where they form cysts. The cysts in E.
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oligarthrus are typically smaller and less aggressive than those in
E. vogeli.
Nematode (Roundworm) Parasites in Human
Nematodes, commonly known as roundworms, are a diverse group
of parasitic worms that belong to the phylum Nematoda. They are
characterized by their long, cylindrical bodies. Several species of
nematodes can infect humans, leading to various health issues.
1. Ascaris lumbricoides
Ascaris lumbricoides is one of the most common and widespread
human parasitic infections. It causes a condition called ascariasis
(Crompton, 2001). These roundworms can grow up to 12-16 inches
in length and live in the small intestine. Infection occurs when
individuals ingest the eggs from contaminated soil or food, and the
worms can lead to symptoms like abdominal pain, diarrhoea, and
malnutrition (Pawlowski, 1978).
2. Enterobius
The genus Enterobius encompasses a diverse group of
roundworms that inhabit a wide range of environments, including
terrestrial, aquatic, and parasitic habitats. They are exclusively
parasitic nematodes that primarily infect the intestines of primates,
including humans, chimpanzees and various monkey species. They
are characterized by their small size, typically ranging from 1 to 5
millimeters in length, and their threadlike appearance.
They exhibit a direct life cycle. The definitive host is human. Once
ingested, the eggs hatch in the intestines, releasing larvae that
migrate to the cecum and colon. The larvae mature into adult
worms, which mate and produce eggs. The adult female worms
migrate to the perianal region at night to deposit their eggs, causing
the characteristic pruritus ani (anal itching) associated with
enterobiasis. The eggs are then shed in the faeces, completing the
life cycle.
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Enterobius species are responsible for enterobiasis, a common
parasitic infection that affects millions of people worldwide.
Enterobiasis is characterized by anal itching, sleep disturbances,
and irritability. While enterobiasis is generally considered a mild
infection, it can cause significant discomfort and disruption to
sleep (Cook, 1994) (Fry & Moore, 1969)..
a) E. vermicularis: This is the most common species of
Enterobius and is responsible for enterobiasis, also known as
pinworm infection. Enterobiasis is the most common parasitic
infection in the United States, affecting an estimated 400 million
people worldwide. It is most common in children, but can affect
people of all ages. Enterobiasis is caused by ingestion of eggs from
the feces of an infected person. Once ingested, the eggs hatch in
the intestines and release larvae, which migrate to the cecum and
colon. The larvae mature into adult worms, which mate and
produce eggs. The eggs are then passed out in the faeces,
completing the life cycle (Cook, 1994; Fry, & Moore, 1969;
Ariyarathenam et al., 2010).
b) E. anthropopitheci: This species is responsible for pinworm
infection in chimpanzees. Enterobius anthropopitheci is
morphologically distinguishable from the human pinworm (Hugot,
1993).
c) E. brevicauda: This species is found in squirrel monkeys
(Sandosham, 1950).
d) E. buckleyi: This species is found in marmosets (Brooks &
Glen, 1982).
e) E. callithricis: This species is found in marmosets (marmosets
(Brooks & Glen, 1982).
f) E. duplicidens: This species is found in monkeys (Inglis,
1961).
g) E. emodensis: This species is found in macaques (Hasegawa,
et al., 2018).
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h) E. foecunda: This species is found in monkeys (Foitova et al.,
2008).
i) E. gregorii: This species is a disputed species that is
supposedly a sister species of E. vermicularis. Its existence is
controversial, however; Totkova et al. (2020) found that E.
gregorii is not genetically distinct from E. vermicularis.
j) E. inglisi: This species is found in monkeys (Totkova et al.,
2003).
k) E. interlabiata: This species is found in squirrel monkeys
(Inglis, 1961).
l) E. lagothricis: This species is found in spider monkeys
(Buckley, 1931).
m) E. lemuris: This species is found in lemurs (Hugot, et al.,
1996).
n) E. lerouxi: This species is found in monkeys (Sandosham,
1950).
o) E. macaci: This species is found in macaques (Sandosham,
1950).
p) E. magnispicula: This species is found in monkeys (Li et al.,
2019).
q) E. paraguerezae: This species is found in monkeys (Hugot et
al., 1996).
r) E. parallela: This species is found in monkeys (Remm &
Remm, 2008).
s) E. pesteri: This species is found in monkey (Wahid, 1961).
3. Trichuris
Genus Trichuris comprises multiple species of parasitic
roundworms that infest the large intestine of mammals, commonly
referred to as whipworms due to their elongated, whip-like
structure (Shears & Grencis, 2022). Trichuris species, responsible
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for a parasitic infection known as trichuriasis, are prevalent
worldwide.
a) T. trichiura: Trichuris trichiura, the most prevalent Trichuris
species causing trichuriasis in humans, is a relatively large worm,
reaching lengths of up to 50 mm. Distinguished by their whip-like
shape, adult worms exhibit a slender front end and a broader rear
end, with females being larger than males (Shears & Grencis,
2022). Barrel-shaped eggs, featuring bipolar plugs, are excreted in
the faeces of infected individuals, contaminating soil and water.
Infection occurs through ingesting eggs, typically from tainted
food or water. Upon ingestion, the eggs hatch in the intestines,
releasing larvae that migrate to the cecum and colon. Maturing into
adult worms, they attach to the intestinal mucosa, feeding on blood
and tissue secretions. Trichuriasis is prevalent in developing
countries with poor sanitation, affecting over 800 million people
globally. Symptoms vary, with mild infections showing no
symptoms and severe cases causing abdominal pain, diarrhoea and
anaemia (Stephenson et al., 2000).
b) T. suis: It infects pigs, closely resembles Trichuris trichiura
but is slightly smaller, measuring up to 40 mm. This species does
not infect humans.
c) T. vulpis: Trichuris vulpis, infecting dogs and foxes, is smaller
than Trichuris trichiura and Trichuris suis, measuring up to 35
mm. It does not infect humans.
d) T. muris: Trichuris muris, infecting mice, is the smallest
Trichuris species, measuring up to 25 mm. It does not infect
humans.
e) T. campanula: Trichuris campanula, infecting cats, resembles
Trichuris vulpis but is slightly smaller, measuring up to 30 mm. It
does not infect humans (Lima et al., 2017).
These species represent only a fraction of the Trichuris genus,
which also includes Trichuris serrata, Trichuris ovis, and
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Trichuris gracilis. They are distributed globally, infecting various
mammals.
4. Ancyclostoma
The genus Ancylostoma stands as a notable representative of
parasitic nematodes, commonly referred to as hookworms (hook-
like mouthpart). These microscopic yet impactful organisms have
a significant impact on both human and animal health.
Ancylostoma species exhibit a complex lifecycle involving larval
migration through host tissues. The hookworms feed on blood in
the small intestine, often leading to anemia and malnutrition in the
host. In addition to their impact on human health, Ancylostoma
species contribute significantly to veterinary health concerns,
affecting domestic animals worldwide. The genus Ancylostoma is
distributed globally, with specific species thriving in diverse
climates. The prevalence of these hookworms is often associated
with regions marked by poor sanitation, where transmission is
facilitated through contaminated soil.
a) A. duodenale: Known as the Old World hookworm, primarily
infests humans, particularly in regions with inadequate sanitation.
b) A. caninum: The primary culprit for hookworm infections in
dogs, with the potential to affect humans as accidental hosts,
leading to conditions such as cutaneous larva migrans.
c) A. braziliense: Infecting cats and dogs, this species can also
cause cutaneous larva migrans in humans.
d) A. ceylanicum: This species is found in dogs, cats and
occasionally humans, especially prevalent in tropical and
subtropical areas.
e) A. malayanum: Predominantly identified in Southeast Asia,
affecting dogs and cats.
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5. Necator americanus
It is commonly known as the New World hookworm infecting
primarily human beings. Necator americanus is the primary
representative of the genus Necator. This hookworm species is of
particular medical importance due to its prevalence in various
regions and its impact on human health, causing conditions such as
hookworm disease, characterized by symptoms like anaemia,
fatigue and malnutrition.
6. Wuchereria bancrofti
Wuchereria bancrofti is a filarial nematode that causes lymphatic
filariasis, a disease characterized by the obstruction and swelling
of lymphatic vessels. It's transmitted to humans through the bite of
infected mosquitoes. Lymphatic filariasis leads to lymphedema,
elephantiasis, and hydrocele (Manguin et al., 2010).
The genus Wuchereria primarily includes two significant species
of filarial nematode parasites that cause lymphatic filariasis in
humans.
a) W. bancrofti: This species is distributed in tropical and
subtropical regions. Mosquitoes, primarily Culex,Anopheles and
Aedes species serve as vectors for this species. It causes lymphatic
filariasis, a debilitating and disfiguring condition. The adult worms
reside in the lymphatic system, leading to symptoms such as
lymphedema, elephantiasis, and hydrocele.
b) W. malayi: This species is found in parts of Southeast Asia,
including India, China, Southeast Asia and Pacific islands. Vectors
include mosquitoes, including Mansonia and Anopheles species. It
causes lymphatic filariasis, resulting in lymphedema, elephantiasis
and other severe complications.
These species are transmitted to humans through the bites of
infected mosquitoes, which carry the larvae of Wuchereria. Once
inside the human host, the larvae mature into adult worms,
primarily residing in the lymphatic vessels. The presence of adult
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worms and the immune response to the parasites contribute to the
chronic and disabling symptoms associated with lymphatic
filariasis. Efforts to control and eliminate lymphatic filariasis often
involve mass drug administration programs targeting the parasites
in endemic areas. The medications used in these programs, such as
diethylcarbamazine (DEC) and albendazole, aim to reduce the
transmission of the disease and alleviate symptoms in affected
individuals.
Conclusion
From an ecological standpoint, helminths are integral components
of food webs and nutrient cycling. Their interactions with various
host species contribute to the regulation of populations and the
maintenance of biodiversity. Their complex life cycles involve
multiple hosts, highlighting their adaptability and intricate
interdependence within their respective environments.
Consequently, any disruption in the helminth-host equilibrium can
have cascading effects on ecosystems, influencing species
composition, abundance and overall stability.
The relationship between helminths and the ecosystem underscores
the need for comprehensive studies that delve into the multifaceted
nature of these parasitic organisms. While helminths contribute
significantly to the ecological balance, their impact on human and
animal health cannot be understated, necessitating a nuanced
approach to understand, manage, and mitigate the consequences of
their presence.
Paradoxically, the same helminths that play vital roles in ecological
systems can inflict significant harm upon human and animal hosts.
In humans, infections such as soil-transmitted helminthiasis,
schistosomiasis, and filariasis represent major public health
challenges, particularly in impoverished regions with limited
access to sanitation and healthcare. Beyond the direct impact on
human health, helminth infections in animals lead to economic
losses in agriculture and livestock industries, with implications for
food security and livelihoods.
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To effectively manage and control helminthic diseases, a deeper
understanding of their biology is imperative. Research efforts must
focus on elucidating the intricate mechanisms by which helminths
establish infection, evade host immune responses, and manipulate
host physiology. Insights into the environmental factors
influencing helminth transmission, including climate conditions
and habitat dynamics, are equally crucial for designing targeted
interventions and predicting disease spread.
Diagnosing helminth infections typically involves clinical
evaluation, microscopy, and serological tests, depending on the
specific parasite. Treatment options include anthelmintic
medications, which can effectively target and eliminate the
parasites, and in some cases, surgical intervention may be
necessary to remove cysts or severe infections. Additionally,
prevention and control strategies emphasize proper hygiene,
cooking practices, and managing the intermediate hosts in the case
of some parasites.
Advancements in molecular biology, immunology, and
epidemiology have propelled helminth research forward, offering
tools for diagnosis, treatment, and prevention. Molecular
techniques enable the identification of specific helminth species
and the characterization of their genetic diversity, paving the way
for more accurate diagnostics. Vaccines targeting key stages of the
helminth life cycle show promise in conferring immunity, while
anthelmintic drugs continue to evolve, providing more effective
and targeted treatment options.
Collaboration among researchers, healthcare professionals and
policymakers is essential to translate scientific findings into
tangible public health interventions. Integrated control programs,
incorporating mass drug administration, improved sanitation
infrastructure, and health education, are critical for reducing the
burden of helminthic diseases. Moreover, a holistic approach that
considers both the ecological and medical dimensions of helminth
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infections is necessary for sustainable and effective control
strategies.
Comprehensive studies that bridge the gap between ecological and
medical research are crucial for navigating this complex
relationship. Studying helminth parasites can help in developing
innovative control measures for human well-being.
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Chapter-9
INFESTATION OF HELMINTH PARASITES AND THEIR
EFFECT ON HUMAN BEING
Pradeep Kumar, Km Reshu, Shreya Chaudhary and
Neeshma Jaiswal
Department of Zoology, Babasaheb Bhimrao Ambedkar
University, Vidya Vihar, Raibareli Road, Lucknow-226025, Uttar
Pradesh, India
Corresponding Author Email: pkrai302@gmail.com
Abstract
In tropical and sub-tropical regions, helminth infestations have
emerged as a significant health concern, impacting the mental and
physical development of school-age children. This literature
review aims to explore and assess the prevalence of various
helminths affecting diverse hosts, drawing connections between
the type of helminth infestation and its prevalence. The occurrence
of helminth infestations is particularly pronounced in areas
characterized by low sanitation and impoverished rural settings,
exacerbating the challenges posed by the country's low Gross
Domestic Product. Studies reveal that approximately 25% of the
global population is affected by parasitic infections, posing
multifaceted threats to communities. Addressing parasitic
infestations has become imperative, necessitating comprehensive
measures and the development of large-scale strategies to
sustainably promote the health of populations. Effectively
mitigating parasitic infestations involves implementing hygiene
and sanitation practices, fostering proper education, ensuring safe
disposal of fecal waste, and implementing deworming initiatives.
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The utilization of anthelmintics, both in medicinal forms and other
biocontrol methods, stands out as a safer approach for eradicating
harmful parasites within ecosystems.
Keywords: Helminth, Infestation, Tropical, Anthelmintics,
Ecosystem.
Introduction
Helminths are parasitic worms with multiple cells that are visible
to the naked eye. These worms, which can cause diseases in
humans, fall into the categories of nematodes (roundworms),
cestodes (flatworms), and trematodes (leaf-shaped worms)
(Vijayan & Kilani, 2010). Collectively known as helminthiasis,
these diseases are prevalent in developing countries with
inadequate sanitation. The eggs of helminths, acting as infective
agents, are released into the environment through feces, and the
primary route of dissemination is the oral-fecal pathway. The
transmission medium for these diseases includes the disposal of
wastewater, sludge, and fecal sludge, resulting in the
contamination of crops, water sources, and food (Jimenez & Maya,
2007).
Infestations denote the condition of being invaded by pests or
parasites, and a worm infestation specifically refers to the invasion
of hosts, including humans and animals, by helminths. This
parasitic infestation poses a significant health concern in
developing nations, often remaining asymptomatic and eventually
leading to the demise of the host. Approximately 25% of the global
population grapples with parasitic infestations, which can become
endemic in tropical regions, affecting up to 90% of the population
in some tropical areas (Thagafi et al., 2004; Tandon et al., 2019).
In 1947, reports indicated that 2.167 billion people were infected
in the human population (Basha & Penchalaiah, 1947). According
to the World Health Organization (WHO), helminthic infections
affected two billion people (Cerri et al., 2010).
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The elevated prevalence of infestations serves as an indicator of
substandard living conditions, inadequate sanitation, and poor
hygiene practices in society, particularly in underdeveloped
agriculture and rural areas within tropical and sub-tropical regions.
These conditions not only diminish worker productivity and result
in the inefficient utilization of economic resources but also have
adverse effects on the mental and physical well-being of school-
age children (Thagafi et al., 2004 & Kumar et al., 2017).
The occurrence of parasitic infestations is notably higher in
children, attributed to their habits that expose them more favorably
and make them primary carriers of the eggs of various helminth
parasites (Basha & Penchalaiah, 1947; Bharadwaj, 2011). The
prevalence of parasitic infestation varies with age and gender.
Children, with their less developed immune systems, are more
susceptible to infestations and related pathological disturbances.
African children, in particular, face a higher incidence due to a
complex interplay of socio-economic, environmental, and
sanitary-hygienic factors (Hashish et al., 2012).
In India, parasitic infestations pose a significant health challenge,
primarily attributable to unsanitary conditions and the
consumption of contaminated, uncooked food, creating a
conducive environment for a high prevalence of helminthic
diseases. The rapid spread of infestations within the community is
exacerbated by a lack of health awareness and knowledge. By
1977, parasitic infestations had become chronic in rural areas,
driven by a population's inadequate focus on personal hygiene,
poor environmental conditions, and low literacy levels.
Malnutrition frequently accompanies parasitic infestations,
contributing to elevated morbidity and mortality rates. While these
parasites may not be directly fatal, acute infections often lead to
complications such as anemia and malnourishment (Gause et al.,
2007).
Children are more susceptible to malnutrition due to a lack of
awareness among medical professionals in promptly detecting
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early signs of malnutrition (Basha & Penchalaiah, 1947). In India,
the emphasis has traditionally not been on diagnostic techniques or
the manifestation of parasitic diseases, whereas developed
countries manage parasitic infestations through primary health care
and public sanitation measures (Jacobson & Abel, 2007; Gause et
al., 2007).
Numerous countries, in adherence to the World Health
Organization (WHO), have committed to preventing parasitic
infestations by offering antihelminthic drugs either free of charge
or at a low cost (Alomashi & Al-Shabbani, 2019). In the past
century, developed nations have reported the prevalence of
parasitic infestations, a phenomenon attributed to increased global
travel and high population density, presenting clinicians in these
countries with occasional challenges (Rao et al., 2003). The
transmission of parasitic infections occurs through soil, leading to
the classification of these diseases as Soil-Transmitted Helminths
(STH). In low- and middle-GDP (Gross Domestic Product)
countries, STH infections tend to become chronic, affecting over
two billion people globally (Kumar et al., 2017; Britton et al.,
2009).
Common STHs include ascariasis, trichuriasis, and hookworm,
causing prevalent clinical disorders in humans. Ascariasis and
trichuriasis are transmitted fecal-orally, while hookworm and
schistosomal cercariae enter the host through the skin (Britton et
al., 2009). Initially overlooked by the public and the health
community, the World Health Assembly, in 2001, passed a
resolution to control STH morbidity by providing antihelminthic
drugs in tropical and sub-tropical countries. Some helminth
parasites, such as Necator americanus, Ascaris duodenale, and
hookworm eggs, undergo hatching in the soil. The larvae of STH
parasites lodge in pulmonary capillaries, enter the lungs, traverse
the epiglottis, and migrate into the gastrointestinal tract. Notably,
STH does not reproduce within the host, emphasizing the
significance of clinical and epidemiological approaches to control
(Hotez et al., 2006).
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Many helminth parasites primarily impact the gastrointestinal tract
(GIT) due to the toxigenic effects or endotoxins produced by these
pathogens. As the largest intestinal nematode parasite, Ascaris
infects approximately 1 billion people worldwide. Infestations of
the intestinal parasites result in a range of clinical conditions, with
symptoms varying from mild to life-threatening. The majority of
symptoms are linked to the gastrointestinal tract, including
abdominal pain, diarrhea, and vomiting, accompanied by
additional manifestations such as fever, breathlessness, urticarial
rash, eosinophilia, and anemia. Advanced stages of intestinal
parasitic infestations can lead to surgical emergencies (Penchalaiah
et al., 1947; Ramachandran et al., 2012).
In developing countries, gastrointestinal diseases are often
attributed to parasitic infestations. The increased global travel and
high population density also expose clinicians in developed
countries to these conditions on occasion (Rao et al., 2003). GIT
parasites may be subcutaneous, dwelling in the lumen, periluminal,
intravascular, or peritoneal. In some cases, parasites can induce
appendiceal colic. The risk of acute appendicitis is 8.6% for men
and 6.7% for women, with a lifetime risk of appendectomy at 12%
for males and 25% for females (Aydin, 2007).
Barium examinations reveal that numerous parasitic infestations
result in ulceration and nodularity on the surface of the intestinal
lumen. These examinations, particularly barium studies, play a
crucial role in diagnosing intestinal infections and infestations
(Ramachandran et al., 2012). Clinical examinations commonly
involve the analysis of patients' stool and blood, with stool
investigations being the primary method for detecting intestinal
parasites (Desalu et al., 2010). Radiology has assumed a significant
role in both diagnosing and managing intestinal parasite
infestations and their associated complications (Thagafi et al.,
2004).
Fine Needle Aspiration Cytology (FNAC) and fluid cytology serve
as rapid diagnostic tools for parasite infestations. FNAC, initially
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highlighted by Kung et al. in 1989 for cysticercosis diagnosis, has
gained widespread acceptance for examining parasitic infestations
(Tandon et al., 2019). While stool examination is a common
diagnostic approach for gastrointestinal (GIT) parasites, the
histological examination of surgical specimens is also utilized to
complete the diagnosis.
Common soil-transmitted helminths parasite-
1. Roundworm (Ascaris lumbricoides)
Ascaris, the most extensive intestinal nematode parasite, has
afflicted approximately one billion individuals worldwide, leading
to the condition known as ascariasis (Basha & Penchalaiah, 1947).
The symptoms associated with this disease range from
asymptomatic cases to nonspecific abdominal pain and, in severe
instances, intestinal obstruction. Migration of the worms from the
duodenal papilla can result in complications affecting the pancreas.
Notably, pancreatic ascariasis has been documented in regions
highly endemic for the parasite, such as the Kashmir valley in India
(Thagafi et al., 2004).
Ascaris lumbricoides holds the distinction of being the largest
human helminth and a cosmopolitan parasite. Its habitat is the
jejunum (Basha & Penchalaiah, 1947; Khuroo, 1996).
2. Whipworm (Trichuris trichiura)
In common Trichuris trichiura were called human whipworms
because their shape was whip-like. Trichuris is found in moist,
warm, tropical, and sub-tropical countries and also found in
temperate climates (Cooper et al., 2000). The second most
common parasitic infection of humans was Trichuris trichiura in
the tropical region (Bundy & Cooper, 1989).
3. Hookworm (Ancylostoma duodenale)
Ancylostoma were a parasitic nematode it was lives in the small
intestine. The distribution of Ancylostoma duodenale was all over
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the world in India, China, North Africa, South Europe, Southeast
Asia, and South America (Sara & Kathleen, 2013).
Table: 1- Greatest public-health significance of STH
S.N.
Species
Localization
Daily egg
output Per
female worm
Length
(mm)
Life span
(years)
1.
Ascaris
lumbricoides
Samll
intestine
200000
150-400
1
2.
Trichuris
trichiura
Caecum and
Colon
3000-5000
30-50
1.5-2.0
3.
Ancylostoma
duodenale
Upper small
intestine
25000-30000
8-13
5-7
Table: 2- Global estimate of STH infection (millions of cases)
S.N.
Disease
SAS
SSA
LAC
MENA
EPA
India
China
Total
1.
Ascariasis
97
173
84
23
204
140
86
807
2.
Trichuriasis
74
162
100
7
159
73
29
604
3.
Hookworm
59
198
50
10
149
71
39
576
Transmission of helminthes infestation
Helminths are transmitted to humans in different ways. The
simplest mode of transmission is by ingestion of infective eggs that
are passed in the feces of infected people, this can happen in
s
everal
wa
y
s
Eggs that were attached to vegetables are ingested when the
vegetables are not carefully cooked, or washed. Eggs were ingested
from contaminated water resources. Eggs could also ingested by
children during play in contaminated soil; children put their hands
on their mouths, and noses without washing. The egg of the
hookworm was hatched in soil, those people who walk in soil
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barefoot were infected by hookworm because hookworm larva
penetrates the skin. In several cases, infection requires an
intermediate host vector but in some cases, the intermediate vector
transmits the infective stage when it bites the host to take blood, in
some cases the larva has attached to the tissue of the intermediate
host and is ingested in humans when eaten intermediate host
directly (Clonorchis in fish, tapeworms in meat and fish,
Trichinella in meat). The level of transmission in humans depends
on the standard of hygiene, and on the climate which is favourable
condition for the survival of the infective stage.
Types of transmission- Helminths parasites were transmitted to
their host by the following types-
a) Skin penetration- The eggs were shredded into the soil or
freshwater, with the help of intermediate host eggs changed into
infective larva. Larvae penetrate the skin, the receptive host, and
reached into the blood circulation (Afolayan et al., 2019).
b) Foodborne helminths- The host consumes infected uncooked
vegetables, fish, crustaceans, meat, or drinking contaminated water
that include helminths egg, larva, or cyst. Cysticercosis,
Dracunculiasis, and Ascariasis were food-borne helminths diseases
(Torgerson et al., 2014) .
Table: 3- Common foodborne zoonotic helminth disease
S.N.
Helminth parasite
Foodborne zoonotic helminth
disease
1.
Diphyllobothrium
Diphyllobothriosis
2.
Echinococcus granulosus
Echinoccosis
3.
Taenia spp.
Taeniasis/ Cysticercosis
4.
Ascaris lumbricoides
Ascariasis
5.
Capillaria philippinensis
Capillariasis
6.
Trichinella spiralis
Trichinellosis
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7.
Gnathostoma
Gnathostomiasis
8.
Clonorchis sinensis
Clonorchiosis
9.
Fasciola hepatica and Fasciola
gigantica
Fascioliasis
10.
Fasciolopsis buski
Fasciolopsiasis
11.
Paragoninmus westermani
Paragonimiasis
c) Direct method- In the direct method, the eggs were attached
to the host without an intermediate host. The eggs of helminths
were passed through faces, eggs hatch into larvae, and re-infect
their host or another host (Afolayan et al., 2019).
d) Modified direct- Eggs were passed through the soil and
undergo the developmental stage. From the soil, eggs were ingested
by the receptive host or ingested contaminated food and water after
these eggs hatch into larvae, and by penetrating the stomach wall
eggs enter the blood circulation, and the larva developed into an
adult (Afolayan et al., 2019).
e) Bite- Filariasis was transmitted by mosquitoes, loiasis
transmitted by, deerflies, and Onchocerciasis transmitted by black
flies that help in transmitting the worm parasite by biting and
depositing infected larvae.
Effect of parasite on the host- Different modes of parasitic injury
on host –
a) Absorption of food- In the host, parasites depletes the
nutritional level to reach disease level. Diphyllobothrium latum
(fish tapeworm) absorbs a great quantity of vitamin B12 to reach
megaloblastic anemia. Hookworm also absorbs iron to reach iron
deficiency anemia (Omolade, & Okwa, 2018).
b) Mechanical effects- Sometimes parasite cysts, larva, eggs
occur in large numbers causing mechanical damage. In the case of
ascariasis intestinal barrier, block and inter twist were also occur.
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The adhesive structure of the parasite also causes mechanical
damage to the host (Omolade, & Okwa, 2018).
c) Toxins- Parasites produce poisonous substances in the form
of secretions, excretion or proteolytic enzymes, and pigments
which lead to disease and death of the host (Omolade, & Okwa,
2018).
d) Destruction of host tissue- Some helminths larva penetrates
the skin and enters in the body (Omolade, & Okwa, 2018).
e) Ingestion of host’s body constituent- Hookworm and
microfilariae of filarial worms feed on the blood and lymph of the
host, and epithelial cell causes blood and fluid loss (Omolade, &
Okwa, 2018).
Defence mechanism of the host on parasites- These effects were
not as apparent as the parasite effect-
a) Immunity- This has a physiological response directed against
the survival of the parasite. In some cases, antibodies were
produced to destroy the parasite. In helminths infections, cell-
mediated immunity by complement activation occurs (Omolade, &
Okwa, 2018).
b) Tissue reaction- Tissue reactions were defence mechanisms
of the host. In a parasite, invasion reactions were localized in the
vicinity. These usually disappear after the invading organism has
been eliminated, like inflammatory reaction, nodules, and
induction of abnormal growth (Omolade, & Okwa, 2018).
c) Helminths affecting the human eye- Zoonotic helminths
cause blindness ocular disease (the most traumatic event for the
human parasite) in the human eye with severe economic effect to
human company.
d) Helminths infecting eyes (HIE) includes roundworm,
flatworm, and leaf shape worm which were transferred by a vector,
consumption of food, and with the help of surroundings. Adult
helminths parasite localize into ocular tissue or ocular globe causes
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symptoms due to parasitic movement. Ocular alternation includes
lacrimation, conjunctivitis, keratitis, epiphora, and resulting in
vision loss. Ascarid larva migrates, causing impairment or
blindness with the demolition of the visual cortex. Sometimes larva
developed inside the patient’s eye weakening the vision. Immune
reaction parasites elicit in the host affected by blindness. Ocular
symptoms were related to inflammation due to larva and local
immune reaction in retina (Otranto & Eberhard, 2011).
Table: 4- commonly reported helminths infecting eyes-
S. N.
Species
Transfer
Localization
Definitive
Host
1
Angiostrongylus
cantonensis
(Rat lungworms)
shellfish
crustacean
Anterior
chamber,
vitreous
Rat
2
Toxocara canis
(Dog round worm)
Dog feces
Eyebrows,
eyelids
and vitreous
Dog
3
Toxocara cati
(Feline round Worm)
Cat feces
Aqueous humor
and
vitreous
Cat
4
Gnthostoma
spinigerum
Ingestion of
Crustacean
Anterior
chamber eyelid
Dog, cat,
5
Dirofilaria repens
Aedes,
Anopheles,
Culex
Sub conjunctival
Dog
6
Acanthocheilonema
sprenti
Mosquitoes
Anterior
chamber
Beaver
7
Trichinella spp.
Ingestion of
raw meat
Orbit ocular
muscles
Domestic,
and wild
animal
8
Taenia carssicepa
Food
contaminated
By dog feces
Anterior
chamber
Carnivores
9
Echinococcus
oligharthrus
Food
contamin-
ated by wild
carnivores’
dog
feces
Orbit
Wild felids
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10
Fasciola hepatica
Water plants
Anterior
chamber
Domestic and
Wild
Ruminants,
Horse
11
Philophthalmus
lacrimosus
Food
contamina by
eye mucosa
Conjunctival
Birds
Physiology change of parasite and host
Parasitism was related to physiological responses and adaptations.
The host was responsible for physiological changes, physiological
changes affect the fitness and confer benefit or harm to one or both
the symbionts involved. We explain how parasite-host physiological
and behavioral interaction may be altered during parasitism
(Thompson & Kavaliers, 1994).
Physiology and behavior
Physiology include endocrine, immune, neural, and
neuromodulatory that are related to behavior, internal organism
understanding of the reduction of the behavioral incident to the
physiological level. Physiological aspects of behavior were related
to parasitism and the behavior of parasitized hosts (Thompson &
Kavaliers, 1994).
Parasitism and host sex
The production of immunoglobulin was greater in females
(Grossman, 1985) in compression to males, which explains that
female is lower susceptibility to parasitic infection, although cell-
mediated immunity plays a greater role in parasitism, parasitism,
particularly with helminths infection (Wakelin, 1976; Crook 1990;
Wilson, 1993). In the vertebrate host, parasitism influences sexual
behavior. The adaptation of the host depends upon the sex for a
shorter generation to produce new combination to counter the
greater adaptability of the parasite (Thompson & Kavaliers, 1994).
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Discussion and Conclusion
Parasitosis was a public health problem in endemic countries with
temperate climates (Antalya et al., 2007). Helminths parasite
which caused human disease has belonged to the genera
nematodes, cestode, and trematodes Vijayan et al., (2010).
Helminths parasites have been found in developing countries
because in developing countries low sanitation occurs (Cisnersos &
Rendon, 2007). The infestation has the state of being by a pest or
parasite. The helminths infestation occurs in developing countries
and poor rural areas where low sanitation occurs, it has
asymptomatic symptoms and eventually leads to death. 25% world
population was infected by helminths infestation (Thagafi et al.,
2004), similarly (Cisnersos & Rendon et al., 2019; Srivastava et al.,
2018; Hesse et al. 2012 & Jacobson et al., 2007). About 2167 million
people were infected by helminth infestation (Basha et al. 2015),
and 1.4 billion people were infected by helminth infestation
(Mohammed Sultan Khuroo, 1996). Helminths infestation has
more infected children because children’s habits are favorable for
helminths parasite and their immune systems are poor (Basha et
al., 2015; Hesse et al., 2012).
In India, there is a low level of awareness regarding helminth
infestation, primarily due to unhygienic conditions and the
consumption of contaminated, uncooked food, which contributes
to a high incidence of helminth diseases. In rural areas, infestations
can become chronic, influenced by a lack of emphasis on personal
hygiene, poor environmental conditions, and low literacy rates
among the population (Anthony et al., 2007). While parasitic
infections are generally not fatal, they lead to a notably high
morbidity rate.
Soil-Transmitted Helminths (STH) are commonly found in the
soil, with prevalent species including Ascaris, Trichuria, and
hookworm, as reported by Flohr et al. (2008) and Bethony et al.
(2006). The recognition of STH as a significant public health
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concern has been acknowledged by both the medical and
international communities (Brooker et al., 2006).
Most helminth parasites predominantly affect the gastrointestinal
tract (GIT) due to the toxigenic effects or endotoxins produced by
these pathogens. In advanced stages, intestinal parasites can lead
to surgical emergencies (Sinha et al., 2011). Helminth infestation
is a significant concern and constitutes a focal point of study
encompassing epidemiology, clinical manifestations, and its
association with the nutritional status of communities. In India,
current findings align with the reality that nearly three-quarters of
the childhood population experiences undernourishment. The
prevalence of helminth infestation is particularly high in areas with
inadequate sanitation, especially in tropical and sub-tropical
regions. Effective control measures for helminth infestation
involve straightforward approaches such as promoting hygiene and
sanitation, education, proper disposal of fecal waste, and regular
deworming. The utilization of anthelmintic medications and other
biocontrol measures emerges as safer options for eradicating
harmful parasites within the ecosystem.
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overview. Radiographics, 30(1), 253-267.
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Chapter-10
PARASITIC DISEASES: IMPACT ON HEALTH OF
FRESH WATER EDIBLE FISH AND SOME DIAGNOSIS
APPROACHES
Raghuveer Kumar Gupta, Raghvendra Niranjan and Malabika
Sikdar
Department of Zoology, Dr. Hari Singh Gour University, Sagar,
(M.P.)- 470003
Corresponding Author Email: raghuveergupta961@gmail.com
Abstract
Under normal circumstances, fish are in harmony with their
surroundings. Any change in the environment disrupts this
equilibrium, causing stress in the fish and making them more
vulnerable to disease-producing organisms. The interaction
between environment, pathogen and fish showed that the presence
of fish pathogens would result in illnesses only if the host defence
system is impaired and the environment is unfavourable. Good
health and progress will result from a balanced partnership. Fish
have evolved to be able to live and thrive in an aquatic habitat that
is prone to shifting conditions. When water quality deteriorates in
a natural habitat, they migrate to a more hospitable location. This
situation with culture ponds can be complicated. In this chapter we
will discuss parasitic disease in mostly fresh water edible fishes as
well as prevention techniques.
Keywords: Parasitic disease, fresh water edible fishes, Health,
Prevention techniques, Water quality
169 | Parasitic Association
Introduction
The term fish has been used to describe a wide variety of aquatic
animals. We talk about crayfish, jellyfish, starfish, cuttlefish and
shellfish fully aware that when we use the word "fish" in such
contexts, we are not talking about a true fish. Even biologists did
not make such a distinction in the past. Seals, whales, amphibians,
crocodiles, and even hippopotamuses were classified as fish by
natural historians in the sixteenth century, along with a variety of
aquatic invertebrates. Later biologists were more discriminating,
excluding invertebrates first, followed by amphibians, reptiles, and
mammals from the narrowing concept of a fish. A fish is now
defined as an exothermic, gill-breathing and aquatic vertebrate
with fins and skin that is usually covered with scales. Kelp forests,
bays, lakes, wetlands, ponds, coral reefs, Rivers and even deep
ocean areas are essential for fish reproduction, growth, feeding,
and shelter (Adam & Nowak, 2003). Fish is an excellent source of
protein, vitamins D, B2 (riboflavin) and omega-3 fatty acids. Fish
is high in phosphorus and calcium, as well as iron, zinc, potassium,
iodine and magnesium.
Aquaculture has helped increase fish production and has emerged
as the best alternative food source for many people. Furthermore,
it makes seafood more affordable and accessible to everyone. Fish
capture is initially necessary for fish production. However, the
majority of the captured fish is used for industrial purposes and
consumed by humans. After China, India is the world's third-
largest fish producer and second-largest aquaculture nation. In
India has demonstrated Blue Revolution importance of the
aquaculture and fishing industries. Production of fish in India has
increased dramatically, with output increasing in 1950-51, 0.65
million MT to 14.16 million MT now (Barber, 2007). Production
of marine fish dominated overall fish production till 2000.
However, thanks to the practice of science-based fisheries, India's
inland fisheries have witnessed a turnaround and now provide 70%
of total fish output (Barber, 1995).
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India has around 2.36 million Ha of Tanks & Ponds area where
culture-based fisheries is popular and accounts for the majority of
overall fish output. The present tank and pond output is 8.5 million
MT. The Department has emphasised expanding the horizontal
area under tanks and ponds as a significant contributor to output in
order to meet the goal production of 13.5 million MT. Saline water
aquaculture encourages to convert 'Waste land to Wet-lands' by
expanding fish production area from 13 thousand Ha to 58
thousand Ha. Himalayan nations provide a distinct value
proposition in cold water fishing. India is concentrating on
boosting its present cold water fish output of 52,084 MT to 90
thousand MT in order to maximise its potential. Reservoirs are
known as "sleeping giants'' because, despite their huge size, cage
culture generates about 3.81% of total inland fish output. The
Indian government intends to use the potential of 3.54 million Ha
of reservoirs under PMMSY. Many strategies have been
implemented to promote cage culture in reservoirs in a sustainable
way in order to optimise production through culture-based fisheries
in small and medium reservoirs. The Indian government has
concentrated on expanding existing fish output through cage
culture from 2.44 lakh MT to 6.29 lakh MT in order to maximise
its potential.
India has 14 major, 44 medium, and countless minor rivers that run
across 2.52 lakh kilometres and contribute to the present output of
1 lakh tons. The Indian government is focusing on conservation of
indigenous fisheries resources and restoration of natural
productivity through river ranching and 41 Conservation and
Awareness in Riverine Fisheries programme sanctioned under
Blue Revolution in 9 States/UTs in order to maximise the potential
of riverine fisheries. The country's natural wetlands are being
promoted by preserving the biological integrity of significant
natural wetlands via the promotion of sustainable fishing
techniques, adding to the present output of 2.03 lakh tons from 5.5
lakh Ha of accessible land.
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The Indian government intends to produce 5.61 lakh tons in order
to fully use the potential of natural wetlands. It is predicted that 11
billion fingerlings and 8.41 lakh tons of feed will be required yearly
to meet the output objective. States such as Bihar, Uttar Pradesh,
Assam, and Manipur are being targeted, and attempts are being
made to increase output, diversify species, and ensure that the link
between natural wetlands and rivers is restored as a positive health
indicator. Recognizing the significance and potential of the
fisheries sector, the Government of India approve the flagship
scheme, Pradhan Mantri Matsya Sampada Yojana (PMMSY), in
May 2020 as part of the Aatmanirbhar Bharat COVID-19 relief
package, with the goal of bringing about the Blue Revolution
through sustainable and responsible fisheries development.
PMMSY represents the largest ever investment in the fisheries
sector, to be implemented over a five-year period in all
States/Union Territories from 2020-21 to 2024-25 in order to drive
the sustainable and responsible development of the Fisheries sector
while ensuring socio-economic development of fishers, fish
farmers, and fish workers.
Many advantages and disadvantages present in aquaculture and
fish farming. Most advantages are high range production of
seafood. Therefore it is easily available in a protein rich diet for
society. Proper feeding is seen as a significant concern in
sustaining normal growth rates, survival rates, and fish health.
Good eating can help reduce the impacts of stress, reduce
susceptibility to disease, and serve as a key means of immune
system strengthening (Alvarez-Pellitero, 2004). Tilapia grows the
fastest when fed a well-balanced diet rich in protein, crabs,
vitamins, lipids, and minerals (Leong, 1997). Fish nutritional needs
differ depending on their life stage. Fish require more nutrition
with a high protein content while they are young, but this decreases
as they age. Fish health and growth are closely tied to the quality
of water in which they are grown.
Physical and chemical variables influence fish development and
productivity in freshwater aquatic environments, respectively
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followed by many types of diseases 9 ( Noga, 1996). Temperature,
turbidity, and other physical qualities of water are critical for fish
generation and growth, whereas significant chemical factors
include pH, alkalinity, hardness, and metals. One of the most
important physical elements influencing fish output is water
temperature. Fish are coldblooded creatures that maintain the same
temperature as their environment. Temperatures outside of the
optimal range might cause lower tolerance to changes in water
quality components (especially metabolites like ammonia) and a
reduction in immune response. As a result, growth rates have
slowed, and in certain situations, a variety of illnesses with
significant mortality rates have emerged. High stocking density,
poor pond habitat, under or overfeeding and the use of excess extra
inputs are all key factors that stress the fish and make them more
prone to illness. Furthermore, this method promotes pathogen
development and proliferation in the aquatic environment.
Many of the known fish illnesses and diseases are the consequence
of stress, poor water quality, overpopulation, and inability to
quarantine any new or sick fish (Paladini, 2017). Water pollution
impacts the pathogenic activity of ecto and endo parasites
dwelling on the body surface or in internal organs of fish.
Contaminants like pesticides may be damaging to parasites, but
fish that have been weakened by parasite infection may be more
vulnerable to the toxic effects of chemicals in the water (Paniagiua,
1998). Many types of fish illness are conditional on organic and
other aquatic pollutants; for example, a decrease in water quality
might be followed by a gill invasion with Cryptobia branchialis.
Reduced pH levels in the water, along with improper breeding
circumstances, can contribute to an ichthyobodo sis epidemic. Poor
sanitary conditions in ponds and reservoirs pose a risk for
myxosporidiosis outbreaks, as do low dissolved oxygen levels.
Thermal pollution can cause fatal ichthyophthiriasis outbreaks.
Domestic sewage discharged into surface waters can be a source of
high trichodina populations. Phenol and polychloroprene may
make fish more sensitive to this parasite, and greater susceptibility
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of carp to this parasite has also been linked to sublethal cadmium
concentrations (Reavill & Robert, 2007). The incidence and
strength of multicellular ecto and endoparasite infestations in fish
are affected by a contaminated aquatic environment (Redonde,
2002). Pollutants in such circumstances operate either on the
intermediate host or directly on the fresh water edible fishes,
affecting the related defence systems and immunological
responses. There is a strong association between a high frequency
of parasites and the condition of the fish in heavily contaminated
water bodies. A bad condition of fish health is caused by the
parasites' amplified impacts on fish affected by the direct
consequences of pollution, rather than by the parasites' main effect
(Rasheed, 1989). Above content we learn different types of
diseases originate due to disturbance of water properties like
bacterial, viral, fungal and parasitic. In this chapter we study some
disease caused by parasites in fresh water edible fishes.
Parasitic fauna of fish
Pure water Because of environmental factors, fish are directly or
indirectly impacted by several types of parasites, which cause
substantial mortality in this species. Protozoa (flagellates, ciliates,
microsporidians, myxozoans), platyhelminthes (Digenean,
monogenean, cestodes), nemathelminthes, acanthocephala, and
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arthropod are the five primary types of parasites that cause illnesses
in fish (Leon, 1998). The physiology of fish makes it easier for
different fatal infections to spread, resulting in mass death.
Furthermore, fish serve as hosts for a variety of parasites, including
gastrointestinal (GI) helminthes, which are important fish
infections that cause significant losses to the fish business.
Parasites disrupt the nutrition, metabolism, and secretary activities
of the digestive system, causing serious harm to the neurological
system and interfering with normal fish reproduction (Kennedy,
2006). Aquaculture development over the last several decades has
resulted in parasite concerns and their relevance for fisheries,
resulting in limits in aquaculture production (Haffman, 1999).
Fish and mammals, including humans, have a lot in common
evolutionarily. Isopod parasites are often big and inflict significant
harm to the host fish. Most fundamental pathological diseases seen
in mammals, such as hyperplasia, necrosis, septicemia,
inflammation, metaplasia, and neoplasia, are also seen in fish
(Kenned, 1999). Fish pathologies and illnesses have also been
utilized as markers of environmental stress. The parasitization can
result in a variety of illnesses in the host fish. Parasites, which are
ectoparasites that cause minimal visible damage in cultivated fish
populations, may become causal agents of major illnesses.
Parasitic disease of fish
Parasites in fish are a widespread occurrence in nature. Parasites
can give information on the ecology of the host population. Fish,
like people and other animals, are susceptible to a variety of
parasite illnesses. Fish have both particulate and non-specific
disease defences. Skin and scales, as well as the mucus layer
released by the epidermis, are non-specific defences that trap
microorganisms and limit their development (Cruz-Lacierda,
2001). If diseases get past these defences, fish can generate
inflammatory responses that increase blood flow to afflicted
regions and send white blood cells that try to kill the germs.
Specific defences, or adaptive immune responses, are specialised
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responses to specific diseases recognized by the fish's body (Chao
et all., 1994) vaccinations, including vaccinations for commercial
food, have become increasingly employed in fish formation in
recent years. Given below Many type of parasitic disease found in
fresh water edible fishes.
1. Protozoa diseases
Protozoans are major
parasites of fish
housed in intensive
fish culture.
Myxozoans,
microsporidians,
ciliates, and
flagellates are the
most common
protozoa groups that
infect fish (Cruz-
Lacierda et all.,
2001). When the host
fish is overloaded, these parasites multiply, causing weight loss,
emaciation, and death. Among the several protozoan groups,
ciliates and flagellates have a direct life cycle and primarily infect
food fishes (Barber, 2008). Ingestion of spores from contaminated
fish or food sources caused the fish to become affected. Multiple
white nodules on the tissues and thickening of the gallbladder wall
are pathological abnormalities caused by these cancer-like
growths. Microsporidian infection of hematopoietic cells can cause
acute anemia.
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1.1. Cryptocaryonosis
Ichthyophthirius,
sometimes known as
"white spot illness" or
"ich," is a parasite disease
that affects edible
freshwater fish worldwide.
Because this parasite can
thrive in a wide range of
temperatures and hosts,
fish without scales, such as catfish, are particularly vulnerable.
Disease may be caused by overpopulation and poor water quality,
which leads to increased tension and impaired immune functioning
in fish, raising the mortality rate (Mandey, 1990).
Gross clinical signs
White, elevated nodules
up to 1mm on the skin and
gills flashing, mucus
development,
sluggishness, shortness of
breath, and
osmoregulatory problems
owing to epithelium and
gill injury are clinical
symptoms. A microscope examination of the gills may reveal
hyperplasia, increased mucus, and tissue injury.
Diagnosis
To confirm the diagnosis, wet-mount cytology of the skin or gills
is examined. Ich is a huge parasite that is fully covered in cilia,
travels slowly, and contains a nucleus in the shape like horseshoe.
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1.2. Amyloodioniosis
Amyloidosis is often known as "velvet disease" because of the
prominent grey spots on the skin and gills. A dinoflagellate called
"Amyloodinium ocellatum" causes the sickness. Dinoflagellates are
external tiny protozoan parasites with flagella, which are long,
hair-like appendages employed as a locomotory organelle (Zafran
et all., 2000). The parasite enters the host's tissue by a short stalk
or peduncle that terminates in a flattened attachment disk with
multiple projections or rhizoids and a movable tentacle-like
stomopode. Mature trophonts can grow to be 120 m in diameter.
This parasite is most commonly seen in the hatchery phase of
culture. It can also have an impact on the fingerling and broodstock
phases.
Gross clinical signs
This parasite condition gives a dusty look or white spots on the
body surface and gills, indicating excessive mucus secretion. The
diseased fish rubs its body against things and swims abnormally on
the surface, with spasmodic gasping and uncoordinated motions.
Fish congregate at the water's surface or near aeration sources. The
body is likewise browning, and the gills are pallid. Localised
bleeding and higher respiratory rates have also been noted.
Diagnosis
Microscopic inspection of skin scrapings or gill filaments reveals
pear or ovoid-shaped trophonts with elongate red stigma around
the attachment point, measuring 150-350 15-70 m in size. Under
reflected light, these trophonts appear white.
1.3. Trichodiniosis
Trichodiniosis is a parasitic illness observed in intrancic fish
culture caused by the ectoparasitic motile ciliate protozoan
trichodinid. Trichodinids have saucer-shaped bodies with cilia
around the periphery. In India, as well as Brunei Darussalam, the
Philippines, Indonesia, Malaysia, and Singapore, it has been
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recorded. This cilliated protopzoic parasite can infect fish at all
stages of development (Williams & Whitaket, 2003). When
parasites are present in large numbers on the skin and gills of fish,
they can interfere with breathing, resulting in significant mortality
among juvenile fish.
Gross clinical signs
Affected fish produce abundant mucus on the body surface and
gills, as well as ragged fins and pale gills. During a serious illness,
fish become feeble. The parasite's spinning motion and sticky disk
can cause direct injury to the branchial epithelium, leading in gill
lesions.
Diagnosis
Microscopic inspection of wet mounts of scrapings from the skin,
scaels, and gills reveals the parasites. The taxonomic feature, the
sticky disk, may be distinguished by staining with silvernitrate
trichrome (AgNO3).
1.4. Renal sphaerosporosis
Renal sphaerosporosis is caused by an endoparasitic myxosporean
infection. It is a form of tiny protozoan that has embedded itself in
many spore shell valves of fish tissues. Sphaerospora epinepheli is
the myxosporean causative agent. The parasite can have an impact
on the nursery, grow-out, and broodstock phases. The parasite's
spores and pseudoplasmodia enter and kill the kidney, liver, gall
bladder, gut, spleen, and blood cells of edible fish (Robert, 2009).
Gross clinical signs
Infected fish lose their balance, float or turn upside down, and
some have hemorrhages on the mouth and body surface. A couple
of the injured fish had hemorrhages in their swim bladders and
enlarged abdomens.
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Diagnosis
The parasite is demonstrated by microscopic examination of spores
and two spherical polar capsules of identical size and diameter
(2.9-4.4 m). Mature spores have a sub-spherical to spherical form,
are 7.8-10 m long, 12.3-14.5 m thick, and 7.0-9.5 m wide. Mature
spores are found in the lumen of renal tubules, whereas
pseudoplasmodia are typically found at the peripheral brush border
of the renal tubule epithelium.
Prevention and control methods of protozoan parasite
The parasite can be avoided by filtering rearing water or
disinfecting it with UV irradiation. Quarantine is required for new
stocks. A refreshing wash will induce the parasite to fall out of the
skin and gills. Chemical bath treatments have been reported to be
0.5 ppm copper sulfate (CuSO4) for 3-5 days or 200 ppm formalin
for 30-60 minutes with high aeration. Treated fish must be
switched to a clean, parasite-free aquarium every three days.
Affected fish can be kept in freshwater for 1 hour every 2-3 days
for 2-3 days, or they can be treated with 0.5 ppm copper sulfate
(CuSO4) for 5-7 days with vigorous aeration (Sitya-Bobadilla &
Alvarez-Paellitero, 1992). Every day, treated water must be
refilled. Infected stocks should be relocated to parasite-free tanks
three times in three days.
2. Helminths diseases
Endoparasites such as Cestode, Tremetode, Nematode, and
Acanthocephalans are found all over the world. Endoparasites
have a mature, immature, and gravid stage, as well as segmented
and unsegmented bodies (Yambot et al., 2003). Like cestode, most
parasites have sticky scolex at the apex. Nematodes, often known
as roundworms, have un-segmented bodies that are typically 1-2
cm long. The mature stage of nematodes may be seen with the
naked eye. Monogeneans are ectoparasites having a posterior
attachment apparatus called a haptor that is equipped with hooks
and suckers. Some monogeneans are large enough to be seen with
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the naked eye, whereas the majority is minuscule. The skin and gill
parasites are the most common monogeneans in groupers.
Didymozoid digeneans are parasitic flatworms that grow to be up
to 80 cm long and create capsules or cysts on the host's gills
(Supamattaya et al., 1990).
2.1. Black-spot disease
The disorder was caused by When cercariae assault the skin and
develop encystations, Posthodiplostomum cuticola forms. When
the host fish develops pigment cells, this encystation becomes
visible to the naked eye. The presence of metacercariae in the skin
does not endanger the fish's health. These black spots can get so
numerous that the fish becomes unappealing to the customer
(Chong & Chao, 1986).
Gross clinical signs
Black spot is a common occurrence in edible fish. Black spot may
be found in longnose sucker, mountain sucker, and spottail shiners
on a regular basis.
Diagnosis
These larvae have only a few hours to discover and burrow inside
a snail or they would die. Each larva clones itself repeatedly once
inside the snail. The newly emerging larval phase is a free-
swimming larva known as a cercaria. These cercarial larvae must
then locate and burrow into a suitable fish, where they create little
cysts.
2.2. Gill monogeneans
The sickness of the gill monogeneans Pseudorhabdosynochus sp.,
Megalocotyloides sp. and Diplectanum epinepheli are the most
usually reported causative agents (Kykova, 1995). They range in
length from 1 to 5 mm. The life cycle takes 14-21 days to complete.
In the nursery, grow-out, and broodstock stages, gill monogeneans
are abundant (Hadfield, 2007). High stocking density increases the
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likelihood of infection. The larvae subsequently cling to the fish's
body surface and travel to the gills.
Gross clinical signs
Affected fish exhibit irregular swimming near the water's surface
as well as a loss of appetite. On the black body surface with
ragged fins and pale gills, mucus production is elevated. In severe
infection, hemorrhagic lesions on the body's surface are
prevalent.
Diagnosis
Gross macroscopic inspection of the diseased fish's body surface
and gills is used to make the diagnosis. Microscopic inspection of
mucus from the gills confirms the diagnosis. The parasites latch
onto the gill filament.
2.3. Skin monogeneans
Several grouper species, including Epinephelus bleekeri, E.
malabaricus, E. coioides, E. fuscoguttatus, E. lanceolatus, E.
tauvina, and Cromileptes altivelis, cause this illness (Koesaryani et
all., 1999). Skin monogeneans range in length from 2 to 6 mm.
Skin monogeneans may have an impact on the nursery, grow-out,
and broodstock stages.
Gross clinical signs
The parasite adheres to fish's eyes, body surface, and gills.
Affected fish brush their bodies against things and congregate
around the source of aeration, flashing their swimming. Fish lose
their appetite and become sedentary. The body surface and eyes of
highly diseased fish are hemorrhagic.
Diagnosis
Gross inspection of the fish's body surface precedes confirmation
by low power microscopic analysis of the parasite. When infected
fish are put in freshwater, the translucent parasite becomes white
and detaches from the host. These capsalid monogeneans are flat
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and oval in shape, with two anterior sucker on the anterior
boundary and a huge opisthaptor on the posterior area, as well as
two pairs of eye spots behind the anterior sucker.
2.4. Nematode diseases
Nematodes are internal parasites with un-segmented bodies that
can grow to be 1-2 cm long. The mature stage of nematodes may
be seen with the naked eye.Epinephelus coioides, E. malabaricus,
and Cromileptes altivelis are the most common agents that induce
infection (Koesaryani et al., 2001). Nematodes can have an impact
on the nursery, grow-out, and broodstock stages.
Gross clinical signs
Non-segmented reddish or black roundworms are attached to
afflicted fish organs such as the fins, branchial cavity, muscles,
parenchyma of digestive organs, and gonads. Fish that have been
severely damaged may have discolored and malnourished skin.
Diagnosis
Gross and microscopic exams are used to examine the parasites.
To reveal the parasite, the afflicted tissues are dissected. A mature
Philometra sp. can grow to be more than 20 cm long.
2.5. Cestodian diseases
Tapeworms are endoparasites that may be found all over the world.
The adult cestode's body is flat and made up of sticky scolex at the
apex, a developing section called the neck, and a strobilus with a
variable number of proglottids (Hughes, 1966). Cestode life cycles
usually require a host and one or more intermediate hosts. Fish can
serve as an intermediate host for various parasite larval stages or
as the primary host.
Clinical signs
Clinical manifestations range from no symptoms to sluggishness,
prolonged loss of appetite, weight loss, long-term intestinal
enlargement, intestinal obstruction, and painful mucosal injury.
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Diagnosis
Cestodes can be extracted from fish, cleaned and rinsed in water,
and then fixed in formalin or 70-99% ethanol. The cestodes can be
retained for a long period at this stage. Histology of adult
tapeworms is useful for examining the major characteristics of the
internal structure of proglottids and for gaining a better
understanding of any disease produced by the parasite.
2.6. Acanthocephalan diseases
Acanthocephalans are differentiated by an invertible proboscis that
is adorned with a series of hooks, the number and arrangement of
which have phylogenetic importance (Overstreet, 2021). Worms
are also known as "thorny headed" or "spiny headed."
Clinical signs
The clinical effect of parasites is determined by the ratio of
parasites to eel body size rather than the amount of parasites in the
fish. As the eels get more infested, they become lethargic and
anorectic. The major symptom is decreased eating, and the evident
sign of gill illness is that the fish seek the surface of the water
because damaged gills allow in less oxygen.
Diagnosis
The parasites obtained are specifically liberated from the host's
tissues. These parasites are attached to the host's tissue by piercing
needles. After being extracted from host tissue, they are stored in
70-95% ethanol for morphological and molecular research.
Prevention and control methods of Helminth Diseases
In order to treat the infection Praziquantel is administered orally in
doses of 50 mg/kg or 5 to 12 gm/kg of feed every 24 hours for 2 to
3 days. Treatment should be administered in a separate tank so that
the eggs of dead cestodes do not spread throughout the tank. A
freshwater bath for 5-30 minutes, depending on host tolerance, or
150 ppm hydrogen peroxide (H2O2) for 10-30 minutes is
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successful in removing parasites from the skin and gills. During
treatment, enough aeration is required.
3. Crustacean diseases
Parasitic crustaceans are widespread in fresh and brackish seas
across the world. When present in modest quantities, they usually
cause very mild damage to their hosts. However, in the event of
severe infections, serious damage to the skin, muscles, and gill
tissue, as well as subsequent infections, can ensue. The epidemic
has severely harmed cultivable freshwater species as well as other
wild species, resulting in severe ulcerations and widespread death.
Labeo rohita, Cirrhinus mrigala, Catla catla, and Cyprinus carpio
are the most severely afflicted species.
3.1. Argulosis
Parasitic crustaceans are widespread in both fresh and brackish
waters. When present in modest quantities, they usually only cause
mild damage to their hosts. However, in the event of severe
infections, serious damage to skin, muscles, and gill tissue, as well
as secondary infections, can ensue (Nagasawa & Cruz-Lacierda,
2004). The epidemic has severely impacted cultivable freshwater
species as well as other wild species, resulting in severe ulcerations
and widespread death. The most severely damaged species include
Labeo rohita, Cirrhinus mrigala, Catla catla, and Cyprinus carpio.
Clinical sign
Directly harm the fish by sucking blood and essential tissue fluids
from the host with their modified mouth parts. In severe
infestations, fish scrape their bodies against rocks, causing
irregular swimming, growth retardation, and occasionally death.
Ulcerated skin is more vulnerable to subsequent bacterial infection.
3.2. Ergasilosis
Ergasilus, sometimes known as "gill lice," are widespread
freshwater parasites that adhere to the gill filaments of their host
fish. Ergasilus sp., the causative agent, is a host-specific
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ectoparasite that infects numerous freshwater fish species,
including yellow perch, brook trout, salmon, and big and small
mouth bass (Longshow & Feist, 2001). Men are the target tissues.
Specifically, gills.
Clinical sign
Gill lice adhere to the gills of fish and feed on the blood and tissue
of their hosts. This connection produces severe tissue damage and
inflammation, perhaps making the fish vulnerable to secondary
infection by bacteria, fungi, and viruses. Ergasilid copepods feed
on the blood and epithelium on the body surface, gills, and
bronchial and nasal canals of several fish species, including sea
bass, grouper, mullet, pearl spot, and tilapia. Mechanical injury,
petechial hemorrhage, reduced breathing, epithelial hyperplasia,
and anaemia with development retardation can all ensue from
heavy infestations. The feeding activity of the copepod causes
severe gill injury, which frequently results in fish mortality.
3.3. Lerniasis diseases
Gill lice attach themselves to the gills of fish and feed on the blood
and tissue of their hosts. This connection produces severe tissue
damage and inflammation, making fish vulnerable to secondary
infection by bacteria, fungi, and viruses. Ergasilid copepods feed
on the blood and epithelium of numerous fish species, including
sea bass, grouper, mullet, pearl spot, and tilapia (Leong, 1998).
Mechanical injury, petechial hemorrhage, reduced breathing,
epithelial hyperplasia, and anemia with development retardation
can all arise from heavy infestations.
Clinical signs
Anchor worms can be noticed with the naked eye when they
protrude from various spots on fishes, as well as microscopic
analysis of scrapings from infected fishes skin, gills, and fins.
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Prevention and control methods of crustacean diseases
Common salt Sodium chloride for bath therapy 2-3%, potassium
permanganate 2-5 mg/l are used to treat crustacian parasite
infections. 1 mg/l gammaxene therapy is sometimes used in ponds.
The mechanical treatment entails controlling or removing the
submerged vegetation and wooden lattice in the pond since they
will serve as an artificial substrate for argulus egg deposition and
can be removed at intervals to destroy the eggs.
Conclusion
Parasitism is a type of symbiosis, which is defined as a close and
long-term biological contact between a parasite and its host. Fish
parasitic illnesses, such as protozoic and helminth infections,
represent a serious danger to fish populations. The Crustecian
parasite is one of the most important parasites of freshwater edible
fishes, generating periodic population-level consequences
throughout the last century. Many external parasites prefer to live
on the skin and gills of fish. The majority of isopod fish parasites
are external and feed on blood. Reducing stocking density and
maintaining water quality control are likely to lessen parasitic
disease effect. To avoid the introduction of parasites, care should
be used while introducing new fish. To minimize disease outbreaks
in the region, various batches are raised in separate tanks.
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Chapter-11
ALTERATION OF BEHAVIOUR DUE TO PARASITIC
INFESTATION
Raghvendra Niranjan, Raghuveer Kumar Gupta and
Malabika Sikdar
Department of Zoology, Dr. Hari Singh Gour University, Sagar
(M. P.)- 470003
Corresponding Author Email:
raghvendraniranjan9556@gmail.com
Abstract
The dynamics between hosts and parasites involve complex
interactions among various species, including vectors, free-living
stages, and ectoparasites. Parasites have the ability to adjust their
behavior and life cycle to thrive in changing environments,
acquiring specialized traits to improve their survival and spread
across a variety of habitats. Indirectly modifying host behavior
emerges as a potentially more effective strategy for parasites.
Moreover, parasites need to develop defense mechanisms to
interact with host physiology, particularly the immune system,
ensuring their ongoing existence. In studies involving rodents, the
neuropeptide oxytocin is identified as a crucial mediator in the
avoidance and recognition of infected individuals. Global changes
can disrupt the coordination of reproduction timing among
parasites, vectors, and diverse hosts, as different environmental
cues such as temperature, food availability, and photoperiod
influence the onset of breeding in various species.
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Keywords: Host-parasite, Dynamics, Infestation, Environment
and Neuropeptide oxytocin
Introduction
The transmission of parasites, or their progeny, across hosts is still
a major area of study in parasitology. Comprehending these tactics
is fundamental to practical parts of parasitology, but it's also
critical to answering fundamental biological queries. Host
manipulation, in which a parasite improves its own transmission
by changing host behaviour, is one particularly fascinating mode
of transmission. In order to shed light on both current and historical
research on this transmission mechanism and its limitations, we
begin this chapter with a brief historical review of the
"manipulation hypothesis."
Complex interactions between many species, such as those
involving vectors, free-living stages, and ectoparasites, are known
as host-parasite dynamics. According to the metabolic theory of
ecology, the initial projections about how climate change will
effect disease risk predicted that parasite development rates would
rise with temperature, accelerating parasite transmission and
raising disease risk. (Molinar and others, 2017)
Parasites can also modify their behaviour or life cycle to adapt to a
changing environment. In order to boost their chances of survival
and spread in wildly varied habitats, parasites have acquired
special features. For instance, when environmental conditions are
unfavorable for development, dormancy might allow resilient
parasite stages to stay inside or outside the host with relatively
modest metabolic expenditures. According to Aleuy and Kutz
(2020), dormancy can last for a predetermined amount of time
(diapause) or until the surroundings are conducive to growth.
Early in the 20th century, scientists started to speculate that
parasites could control their hosts (Cram, 1931). Fish taken from
cormorants, which are considered definitive hosts, are much more
likely to be intermediate hosts of the cestode Ligula intestinalis
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than fish taken by fishermen, according to a 1952 study by van
Dobben. In 1977, Bethel and Holmes conducted laboratory tests to
demonstrate that the acanthocephalan Polymorphus paradoxus
cyst acanths cause aberrant behaviours in the amphipod Gammarus
lacustris, which serves as an intermediate host. They subsequently
confirmed that this increased predation risk was due to ducks,
which are the ultimate hosts.
Since then, the study of phenotypic alterations in animals that have
become parasitized has gained popularity among parasitologists. In
addition to being an innately fascinating phenomenon, the theory
that parasites could modify the phenotype of their host and thereby
improve their own transmission gained rapid traction because it
provided parasitologists with a means of illustrating the pervasive
significance of parasites to a wider scientific community. A large
variety of parasites have been shown to elicit changes in host
phenotypes as a result of the remarkable amount of research
conducted on this subject over the past three decades (Barnard and
Behnke, 1990; Poulin, 1998). According to Moore (2002), these
studies have shown that a wide range of host phenotypic traits, such
as behaviour, morphology, and or physiology, can be altered by
parasites. The extent of these alterations can vary greatly, ranging
from minor changes in the percentage of time spent performing a
given activity to the production of complex and spectacular
behaviours.
The trematode Dicrocoelium dendriticum, sometimes known as
the "Brainworm," appears to be the most well-known example of
parasitic manipulation in ecological textbooks. This trematode's
intermediate host, ants, climbs grass blades, a behaviour that likely
facilitates transmission to grazing sheep. But this isn't the best
example of manipulation by parasites. It is challenging to research
sheep's predation of ants, as one might expect, and it is still
unknown how many ants are eaten by these herbivores that are
infected or not. Nonetheless, there are numerous striking instances
of purported host manipulation that lend themselves more easily to
measurement. For example, it has been demonstrated that many
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trophically transmitted parasites modify the behaviour of their
intermediate hosts to make them more susceptible to predatory
definitive hosts (Lafferty, 1999).
Alteration of behaviour
Both direct and indirect methods are available to parasites to
modify host behavior. By engaging with the host's nervous system
or muscles, parasites can directly change the behavior of their host.
For instance, a neuroactive material secreted by a parasite may
alter the behavior of its host. By influencing host organs other than
neurons and muscles, parasites can have indirect impacts on host
behavior, leading to host-mediated behavioral changes. For
instance, a parasite's presence may have an impact on immunity,
host development, intermediate metabolism, and/or metabolism,
which may subsequently change the behavior of the host.
It is doubtful that elucidating the processes driving host behavior
changes will show if the host behavior change is adaptive for the
parasite. Increased parasite transmission can result from both direct
and indirect processes (Adamo, 2002). Mechanistic studies are
necessary, though, to ascertain the possible expenses incurred by
the parasite in causing a behavioral alteration in the host. When
scientists talk about "parasitic manipulation" of host behavior, they
typically mean an active process where the parasite uses its energy
to directly affect its host's behavior. On the other hand, parasites
may modify host behavior without incurring any additional energy
expenditures beyond those necessary for the host to survive (e.g.,
by suppressing host immunity, which results in an accidental
change in host behavior). This is because changes in host behavior
can also be produced indirectly. Furthermore, even direct parasitic
impacts could not cost the parasite anything because parasitic
waste products have the ability to affect host behavior. Even if both
are adaptive for the parasite, the ecological effects of expensive
parasitic manipulation and free, accidental host behavior changes
will differ (Lafferty et al., 2000).
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Direct effects
It has been challenging to show that a parasite's secretions or
excretions directly affect host neurons. The intricate relationships
that exist between the immune system and the neurological system
contribute to the issue. Any tissue, including the central nervous
system (CNS), that is invaded by parasites usually, triggers
intricate, but poorly understood, immune cascades (Kristensson et
al., 2002). It is challenging to distinguish between changes in host
behavior that are caused by the host's immunological response or
by the parasite directly because of these immune neuronal
connections. Furthermore, certain parasites release substances that
are exact replicas of substances released by the host's immune
system (Kavaliers et al., 1999).As per Kavaliers et al. (1999), the
trematode Schistosoma mansoni secretes various opioid peptides,
including beta-endorphin. These drugs impact immune system as
well as neurological function (Duvaux-Miret et al., 1992). It is
unknown if the parasite or the host is the source of the rise in serum
and central nervous system (CNS) opiate and opioid levels in
infected hosts.
Indirect methods
After a thorough analysis of parasitic behavior modification, it is
typically determined that the host behavior change is a result of the
parasite indirectly (Adamo, 2002). This could be due to two
different factors. First off, unless the parasite is located inside the
central nervous system, most parasites are tiny and it might be
prohibitively expensive for them to secrete behaviorally significant
amounts of a neuroactive compound. Inducing the host to make
them might prove to be more effective. Second, parasites need to
develop defense mechanisms to interact with host physiology,
particularly immunity, in order to survive. Coopting the chemical
connections between these systems and the nervous system of the
host to induce adaptive behavioral changes in the host may be a
minor evolutionary step. Due to the close interaction between the
parasite and the host's immune system, immune–neural
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connections may be particularly vulnerable to this kind of
disruption (Adamo, 1997, 2002).It will be challenging to identify
whether the parasite is actively influencing host behavior if this is
a common mechanism of parasitic manipulation. This is because
the majority of alterations in host behavior will resemble host
reactions to stress or infection. For instance, using both direct and
indirect methods, the trematode Trichobilharzia ocellata inhibits
the snail Lymnaea stagnalis, its intermediate host, from laying eggs
(de Jong-Brink et al., 2001).
An understudied theory about a mafia-like manipulation
strategy?
Initially, this process was suggested as a plausible reason for why
a number of bird species tolerate cuckoo eggs and nestlings in their
nests in spite of the significant disadvantage to their own fitness.
Because the consequences of rejecting an egg are greater than those
of accepting it, Cuckoos may coerce the bird host to accept non-
self eggs.
This scenario suggests that both the parasite and the host are able
to detect a wide range of environmental cues related to fitness and
modify their life history decisions (sensu lato) in a state-dependent
way. A growing body of research indicates that this faculty does
exist (Lewis et al., 2002).
Effect on human
There is evidence in the literature that Toxoplasma gondii can alter
human behavior, which heightens its influence on public health. T.
gondii, an intracellular protozoan that was first identified in Brazil
and France at the turn of the 20th century, is the etiological agent
of toxoplasmosis, an infectious disease that can be acquired
congenitally or postnatally and has a global distribution (Lopes-
Mori et al. 2011).
Both the acute and chronic or latent stages of T. gondii infection
can have an impact on the brain; studies assessing these effects
have previously been conducted on rodents as well as immune
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compromised and immune competent humans. Based on
epidemiological research, investigations conducted in immune
competent individuals revealed that latent forms of infection are
the primary cause of behavioral disorders (Fekadu et al. 2010).
According to certain research, in this type of infection, T. gondii
has an impact on the nervous system and behavior (Dabritz and
Conrad 2010). Furthermore, research on rat infections conducted
experimentally showed that T. gondii eliminates the innate
aversion to cat smells (Mitra et al. 2013), supporting the theory that
the parasite may also cause brain abnormalities in humans.
It is unclear whether a T. gondii infection alters a person's
personality or if specific personality traits affect a person's risk of
contracting the parasite. According to longitudinal research,
personality changes become more severe the longer the infection
lasts (Holliman 1997). According to these reports, infections cause
changes in a person's personality rather than the other way around.
Numerous investigations have assessed the connection between
neuro- pathologies and parasite infection (Torrey et al., 2006;
Sutherland et al., 2015). Only a small number of researches,
though, have examined how T. gondii infection affects behavior in
people. Consequently, our goal was to examine the scientific
literature regarding the relationships between anti-T. gondii
antibody seropositivity and neurobehavioral changes in the human
population.
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According to the study, animals like rabbits (Sylvilagus spp.) and
other small native mammals and birds for which the parasite has
serious pathological effects strongly avoid latrines. On the other
hand, animals that could tolerate the parasite better, like rats and
raccoons, were drawn to latrines. This example shows how crucial
the cost of infection is in influencing avoidance behavior. Several
studies have shown that birds steer clear of parasite-filled nest
sites. Great tits are among the species displaying this behavior.
(Opplier et al., 1994)
Conclusion and future aspect
There may be overlap between the modulators of disease
avoidance behaviors, even though the cues and systems that enable
disease detection may differ significantly amongst species. The
neuropeptide oxytocin appears to be a major mediator of the
avoidance (and recognition) of infected individuals in rodents,
where the majority of research on this topic in vertebrates has been
Figure: 1. Transmission and life cycle of
Toxoplasma gondii
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conducted (Kavalier et al., 2019). Since nearly all vertebrates
contain oxytocin or oxytocin-like non a peptides, which regulate
socially relevant physiology and behavior in a variety of taxa,
(Goodson, 2013) Future studies should look into whether non a
peptides have a role in non-rodent taxa's disease avoidance
behaviors as well. Understanding the proximate mechanisms
behind parasite and pathogen behavioral avoidance may be
advanced through inspiration from research conducted on model
organisms invertebrates, such as the nematode Caenorhabditis
elegans (Anderson and McMullan, 2018).
Based on the studies that are currently available, it appears that
migratory escape and avoiding contaminated habitats and infected
nonspecific are the most common forms of avoidance across taxa.
The potential costs and benefits of avoidance, as well as how those
compare to the benefits and costs of infections, are crucial factors
to take into account when creating a cohesive framework for the
occurrence of avoidance behaviors. Generally speaking, the
greatest costs incurred by avoidance behaviors can be attributed to
the loss of resources, including the opportunity for reproduction,
the loss of suitable habitats or territories, or the loss of life in the
event of increased predation. (Amoroso and Antonovics, 2020).
Disgusting landscapes will be impacted by global change on larger
temporal and spatial scales. Global change may decouple the
timing of the reproduction (or breeding) of parasites, their vectors,
and their diverse hosts because different environmental cues, such
as temperature, food availability, and photoperiod, guide the onset
of breeding differently in different species. This could therefore
result in ineffective migratory escape plans, where hosts reach their
destinations during periods of increased parasite or vector
abundance. Furthermore, many species' distributions, dispersal
patterns, and migratory routes are changing due to longer growing
seasons and warmer winter temperatures.
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Chapter-12
PARASITIC ADAPTATION OF FUNGI ASSOCIATED
WITH FLORAL AND FAUNA WITH THEIR ROLE IN
ECOSYSTEM
Danish Ahmad1, Gumal Mohammad2, Deepak Kumar Singh2,
Balwant Singh3*
1Department of Botany, B. P. PG College Narayanpur,
Maskanwa, Gonda (UP) India
2Department of Botany, A. N. D. Kisan PG College Babhnan,
Gonda (UP) India
3Department of Botany, K. S. Saket PG College Ayodhya (UP)
India
*balwantsingh1642@gmail.com
Abstract
Parasitism in fungi refers to a symbiotic relationship where one
fungus, the parasite, derives nutrients at the expense of another
organism, typically a plant or animals or another fungus, known as
the host. Fungal parasites can have significant ecological and
economic impacts, as they can cause diseases in plants and affect
various ecosystems.
Keywords: Parasite, Parasitism, Host, Animal Association, Myco-
parasites.
Introduction
Fungal parasitism refers to the symbiotic relationship where a
fungus, the parasite, derives nutrients from another organism,
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typically a plant or another fungus (the host), often at the expense
of the host's well-being. This dynamic interaction is central to
understanding the ecological balance within diverse ecosystems.
The diversity of fungal parasites, ranging from rusts and smuts that
afflict plants to animal parasites causing mycoses. Different classes
of fungi exhibit specialized strategies for invading hosts,
emphasizing the variety of tactics employed in establishing
parasitic relationships.
An exploration of how fungal parasites infect their hosts is crucial
for understanding the pathogenesis. Discussion includes the
production of specialized structures like haustoria, the release of
enzymes to breach host defences, and the formation of distinctive
spore types. The life cycle, often involving both sexual and asexual
reproduction, contributes to the resilience and adaptability of
parasitic fungi. The economic implications of fungal parasitism,
especially in agriculture where crop diseases can lead to significant
yield losses. Concurrently, the ecological impact of these
interactions is examined, emphasizing the role of parasitic fungi in
maintaining biodiversity, regulating population dynamics, and
contributing to nutrient cycling within ecosystems. Understanding
the dynamics of parasitism in fungi is crucial for mitigating the
negative impacts on agriculture, forestry, and natural ecosystems.
Research into the molecular mechanisms underlying these
interactions can contribute to the development of effective
strategies for disease control and sustainable management
practices.
The concept of coevolution between hosts and parasites is
discussed, exploring how these dynamic interactions drive the
evolution of resistance mechanisms in hosts and counter-
adaptations in parasites. The intricate dance of coevolution
contributes to the ongoing diversification of fungal parasites and
their hosts. The chapter delves into the strategies employed to
manage and control fungal diseases caused by parasitic fungi,
emphasizing the importance of integrated pest management,
resistant crop varieties, and sustainable agricultural practices.
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These strategies are crucial for mitigating the impact of parasitic
fungi on crop yields and ecosystem health.
Parasitism in fungi is a fascinating aspect of their ecological roles,
influencing the dynamics of ecosystems and shaping the
interactions between organisms. This chapter explores the various
dimensions of fungal parasitism, highlighting its significance in
both natural ecosystems and agricultural landscapes. The chapter
concludes by addressing emerging research avenues and the
potential applications of understanding fungal parasitism in fields
such as biotechnology, conservation, and medicine. As we uncover
more about the intricacies of these symbiotic relationships, the
chapter reflects on the ongoing importance of fungal parasitism in
shaping the natural world.
Major Parasitic Classes of Fungi
The major classes of fungi that exhibit parasitic behavior,
elucidating the diversity within these classes and their profound
impact on various hosts. Understanding the characteristics of these
parasitic fungi is essential for comprehending the complex
dynamics of ecological systems.
1. Rust Fungi (Pucciniomycetes):
The chapter begins by delving into rust fungi, a diverse group
notorious for their impact on plant health. Rusts exhibit a high
degree of host specificity and are responsible for diseases affecting
a broad range of crops, including wheat, coffee, and pine. Their life
cycle, often involving multiple host plants, adds complexity to
their parasitic strategies.
2. Smut Fungi (Ustilaginomycetes):
Smut fungi, with their distinctive black spore masses, are
highlighted for their parasitic relationships with grasses and
cereals. Their ability to induce malformations in host plants, such
as corn smut, contributes to economic losses in agriculture. The
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chapter explores the mechanisms smuts employ to colonize and
manipulate host tissues.
3. Powdery Mildews (Erysiphales):
The discussion then shifts to powdery mildews, widespread plant
pathogens known for the powdery growth they produce on leaves
and stems. These fungi impact a wide array of crops, from roses to
grapes, affecting photosynthesis and overall plant health. The
chapter examines their specialized structures and strategies for host
invasion.
4. Oomycetes (Oomycota):
While not true fungi, oomycetes are often grouped due to similar
ecological roles. The chapter explores their parasitic behavior, with
a focus on Phytophthora infestans, the causal agent of the Irish
potato famine. Oomycetes' impact on plants and their unique life
cycle contribute to their significance in the context of fungal-like
pathogens.
5. Ascomycetes (Ascomycota):
Ascomycetes, a diverse class encompassing both symbiotic and
parasitic species, are discussed for their role in various plant
diseases. Apple scab, Dutch elm disease, and other examples
illustrate the diverse strategies employed by ascomycetes in
parasitizing plants. The production of sexual spores within sac-like
structures (asci) is a characteristic feature.
6. Basidiomycetes (Basidiomycota):
The chapter then explores basidiomycetes, a class with both
mycorrhizal and parasitic representatives. Rusts and some smuts
belong to this class, showcasing their diverse ecological roles.
Cryptococcus neoformans, causing disease in humans, is
mentioned to emphasize the impact of basidiomycetes beyond the
plant kingdom.
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7. Zygomycetes (Zygomycota):
The discussion concludes with an examination of zygomycetes,
which, while predominantly saprophytic, can act as opportunistic
parasites in animals. Mucormycosis, a fungal infection in animals
and humans, exemplifies the medical significance of some
zygomycetes. The chapter explores their life cycle and
implications for animal health.
Phyto-Parasites of Fungi
The captivating world of phyto-parasitic fungi, delving into the
intricate relationships these organisms establish with their plant
hosts. Phyto-parasites, a diverse group within the fungal kingdom,
are central players in shaping the health and dynamics of plant
populations. This chapter aims to unravel the mechanisms, impact,
and significance of fungal phyto-parasitism in the broader context
of ecosystems and agriculture.
The phyto-parasitism is defining as a symbiotic relationship where
fungi derive nutrients from plant hosts. Unlike mutualistic
mycorrhizal associations, phyto-parasitism involves a one-sided
nutrient extraction, often leading to diseases that can significantly
impact plant health.
Diversity of Phyto-Parasites
An exploration of the major classes and groups of phyto-parasitic
fungi is undertaken, including rusts, smuts, powdery mildews, and
other pathogenic fungi. Each group is characterized by distinct life
cycles, infection strategies, and host specificities, contributing to
the rich tapestry of plant-fungus interactions.
Infection Mechanisms:
The varied mechanisms employed by phyto-parasitic fungi to
infect and colonize their plant hosts. This includes the development
of specialized structures such as haustoria, the secretion of
enzymes to breach host defenses, and the manipulation of host
physiology to create a conducive environment for fungal growth.
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Impact on Plant Health and Agriculture:
A significant portion of the chapter is dedicated to understanding
the impact of phyto-parasitic fungi on plant health and agricultural
productivity. Examples of devastating diseases caused by these
fungi, such as wheat rust, corn smut, and grape powdery mildew,
underscore the economic and ecological consequences of phyto-
parasitism.
Host Specificity and Coevolution:
The discussion explores the concept of host specificity among
phyto-parasites, emphasizing how certain fungi have evolved to
infect specific plant species or even particular tissues. The chapter
also delves into the dynamic process of coevolution between plants
and phyto-parasites, shaping the genetic landscape of both parties
over time.
Management Strategies:
The chapter addresses strategies for managing and mitigating the
impact of phyto-parasitic fungi on crops, including the use of
resistant plant varieties, cultural practices, and fungicides. It
emphasizes the importance of integrated pest management
approaches in ensuring sustainable and effective control measures.
Ecosystem Dynamics and Conservation:
A broader perspective is taken to explore the role of phyto-
parasites in ecosystem dynamics. While they can be detrimental to
individual plants, these fungi contribute to the overall diversity and
resilience of ecosystems. The chapter discusses the ecological
significance of phyto-parasites and their role in maintaining
biodiversity.
Animal Parasites of Fungi
This chapter delves into the intriguing realm of fungal parasites
that have crossed the kingdom barrier to target animals. While
fungi are traditionally associated with plant and microbial
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parasitism, certain species have adapted to exploit animals as hosts.
This chapter explores the diversity, impact, and ecological
significance of these fungal animal parasites.
The chapter profiles key examples of animal parasitic fungi,
including those causing diseases in mammals, birds, amphibians,
and insects. Notable examples such as Geomyces destructans,
responsible for bat white-nose syndrome, and Batrachochytrium
dendrobatidis, causing chytridiomycosis in amphibians, are
discussed in detail.
Infection Mechanisms and Pathogenesis:
An exploration of the infection mechanisms employed by animal
parasitic fungi follows, shedding light on how these fungi breach
animal defenses and establish infections. The chapter outlines the
diverse strategies, from the production of specialized spores to the
secretion of enzymes, that allow fungi to thrive within animal
hosts. The pathogenesis and impacts on host health are also
discussed.
Medical Significance:
The chapter addresses the medical relevance of animal parasitic
fungi, focusing on those causing mycoses in humans. Examples
include fungi of the genera Aspergillus and Candida, which can
lead to respiratory and systemic infections in
immunocompromised individuals. The discussion emphasizes the
importance of understanding these infections in the context of
human health.
Zoonotic Potential:
The potential for zoonotic transmission, where fungal infections
can jump from animals to humans, is explored. This section
outlines the challenges in preventing and managing zoonotic
fungal diseases, emphasizing the interdisciplinary nature of
research required for effective surveillance and control.
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Ecological Roles and Conservation Implications:
The chapter broadens its perspective to examine the ecological
roles of animal parasitic fungi, considering their impact on wildlife
populations and ecosystems. The potential role of these fungi in
regulating animal populations and influencing biodiversity is
discussed, along with implications for conservation efforts.
The Role of Parasitic Fungi in Ecosystems
The intricate and often overlooked contributions of parasitic fungi
within ecosystems is significant. While traditionally perceived as
agents of disease and disruption, parasitic fungi play multifaceted
roles that extend beyond their immediate impact on individual
hosts. This chapter aims to uncover the nuanced interactions and
ecological significance of parasitic fungi in maintaining the
balance and diversity of ecosystems. It emphasizes the diverse
strategies employed by these fungi to interact with their hosts,
ranging from subtle symbiotic relationships to aggressive
pathogenesis.
Population Dynamics and Regulation:
An exploration of how parasitic fungi contribute to the regulation
of host populations follows. By causing diseases and influencing
the reproductive success of certain individuals, parasitic fungi act
as ecological regulators, preventing unchecked population growth
and fostering biodiversity.
Nutrient Cycling and Decomposition:
The vital role of parasitic fungi in nutrient cycling within
ecosystems. As they decompose organic matter, including the
remains of infected hosts, these fungi release essential nutrients
back into the environment. This process facilitates nutrient
recycling, benefiting the entire ecosystem.
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Creation of Microhabitats and Biodiversity Hotspots:
The presence of parasitic fungi creates microhabitats within
ecosystems. For example, the decay of wood by wood-decaying
fungi provides unique niches for various microorganisms and
invertebrates. These microhabitats contribute to local biodiversity
and serve as hotspots for ecological interactions.
Host-Parasite Coevolution:
The discussion delves into the concept of coevolution between
hosts and parasitic fungi. The ongoing arms race between hosts
developing resistance mechanisms and parasites evolving to
overcome these defenses contributes to the genetic diversity and
adaptability of both parties, shaping the long-term dynamics of
ecosystems.
Control of Invasive Species:
The potential role of parasitic fungi in controlling invasive species.
Some fungi exhibit specificity towards non-native species,
providing a natural biocontrol mechanism that helps mitigate the
impact of invasives and maintain the integrity of native
ecosystems.
Research Implications and Conservation Strategies:
Consideration is given to the implications of understanding the
ecological roles of parasitic fungi for research and conservation.
The chapter discusses how insights into these interactions can
inform conservation strategies, especially in the context of
endangered species and ecosystems facing various environmental
challenges.
Conclusion
In concluding the chapter, the multifaceted nature of phyto-
parasitic interactions is emphasized. By understanding the
mechanisms and consequences of these interactions, researchers
and practitioners can develop strategies for sustainable agriculture,
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contribute to ecosystem conservation, and unlock the potential of
fungal biology for the benefit of both plants and humans.
While parasitic fungi can have detrimental effects on individual
organisms, their roles in ecosystems highlight the complexity of
ecological interactions. Studying these interactions is crucial for
gaining a comprehensive understanding of ecosystem dynamics
and for developing effective strategies for conservation and
sustainable ecosystem management.
The chapter aims to foster a deeper appreciation for these
organisms, highlighting their pivotal roles in shaping the
ecological tapestry and promoting resilience in the face of
environmental changes.
***
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About the Editors
He is a Young and Active Researcher and Academician related to
Babasaheb Bhimrao Ambedkar Central University Lucknow, India
and Dr. Ram Manohar Lohiya Avadh University Ayodhya, Uttar
Pradesh, India. He has published more than 10 Research Articles
in National and International Journals and more than 10 Book
Chapters and also 8 Books in his credits. He has also participated
in more than 75 National and International Seminar, Conferences
and Workshops. Editor is the Life Members of National Bodies
like Indian Science Congress Association, Asian Biological
Research Foundation, Indian Academy of Science and Technology
Society & Glocal Environmental and Social Association. He also
received some prestigious awards like- Young Scientist Award,
Incredible Publication Award, Young Botanist Award, Young
Researcher Award, Crop Science Innovation Award.
She is a Potential Researcher and Academician with 5 Years of
Teaching and 4 Years Research Experiences. She is specialized in
the field of Parasitology and Fisheries. She has published 7
Research Articles in National and International Journals and Book
Chapters. She has also participated in several National and
Dr. Balwant Singh
M.Sc.-AAS, M.Sc.-Botany, Ph.D. Botany
K. S. Saket P.G. College Ayodhya
Dr. Ram Manohar Lohia Avadh University, Ayodhya, Uttar
Pradesh, India
balwantsingh1642@gmail.com
+91 7408600478, 9161734338
Dr. Anita Singh, M.Sc., Ph.D.
Assistant Professor
Sri Aurobindo College, University of Delhi, India
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International Seminar, Conferences and Workshops. Some
prestigious awards like- Young Scientist Award, Presentation
Awards in his credit.
She is an Active Researcher and working as Young Scientist post
in Department of Microbiology, King George’s Medical
University, Lucknow, Uttar Pradesh, India. She has 5 Years of
Research Experience in Mycology Laboratory. She has published
more than 8 Research and Review Papers in National and
International Journals, more than 10 Book Chapters and also 4
Books in his credits. He has also participated in more than 25
National and International Seminar, Conferences and Workshops.
He is an energetic and emerging researcher and academician with
a focus on Veterinary and Fish Parasitology. Accumulating over
seven years of expertise in Enviro-Parasitology and Molecular
Biology Techniques, he holds master’s degree as M.Sc. in Zoology
from the University of Allahabad, Uttar Pradesh, obtained in 2016.
His academic contributions encompass the publication of more
than six research articles in both national and international
journals, along with numerous chapters in books. Actively
participating in scholarly discussions, he has engaged in over 50
national and international seminars, conferences, and workshops.
As a respected member of various national organizations, he holds
lifelong memberships in bodies such as the Indian Society of
Parasitology, the International Association of Zoologists, and the
Indian Science Congress Association. In recognition of his
Dr. Shivangi Tripathi, M.Sc., Ph.D.
King Georg Medical University Lucknow, India
Integral University Lucknow, India
Dr. Pradeep Kumar, M.Sc., Ph.D.
Department of Zoology, School of Life Science
Babasaheb Bhimrao Ambedkar Central University Lucknow,
India
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commitment and accomplishments, he has received prestigious
awards, including the Young Scientist Award, Best Young
Scientist Award, and commendations for outstanding Oral and
Poster Presentations Awards.
The Editor is well known for his great work in the field of Botany
especially in Phycology and Biodiversity and Phytochemistry in
Researcher. He has more than 05 years research experiences in
their field. He has published more than 30 National and
International Research Articles in reputed Journals. He has also
published 16 Books and more than 12 Book Chapters. Editor also
has participated more than 40 National and International Seminar,
Conference and Workshops. Beside this, the editor also works as
several National and International Journals Member of Reviewer
Board and Editorial Board also work Deputy Chief Editor. He also
received award like Best Presenter Award-2021, Young
Researcher Award 2021, AIB-VSC-Best Young Speaker Award-
2021, Best Young Scholar, Award of Best Book Chapter, Best
Researcher Award. An Indian Patent also in his credit for Heavy
Metal Identification Gloves Using Nano-Technology.
Dr. Mukul M. Barwant, M.Sc., Ph.D.
Department of Botany
Sanjivani Arts Commerce and Science College, Kopargaon,
Maharashtra.
Yashavantrao Chavan Institute of Science, Satara,
Maharashtra, India
mukulbarwant97@gmail.com
+91 7057529221
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.....Thank You
