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Synlophe Patterns of the Haemonchinae of Ruminants (Nematoda: Trichostrongyloidea)
... Those changes have important implications for the development of new approaches for the diagnosis, treatment and control of parasitic diseases, and to study the taxonomy, population genetics, ecology and epidemiology of parasites (Gasser RB, 2006). Parasitic nematodes have been traditionally identified and distinguished on the basis on their morphology using features such as cuticular ridge patterns, sublateral hypodermic chords and morphometrics of the male bursa and spicules (Lichtenfels JR, 1988;Lichtenfels et al., 1994;Lichtenfels JR, 1994;Lichtenfels and Pilitt, 2000). However, these approaches are specialist and time consuming and often insufficient for specific identification. ...
... Hybridization would also have important implications for the role of alternative reservoir hosts where co-infections may be common (Zinsstag et al., 1997). (Lichtenfels and Pilitt, 2000). ...
... For 12 sheep, eight goats, two cattle, all worms were identified as H. contortus (homozygous A at rDNA ITS-2 P24) (Fig. 2.1). For the remaining four cattle, which contained worms with the physical appearance of Mecistocirrus, the pyrosequence genotypes were consistent with a M. digitatus species identity; homozygous P25 (A), P28 (A) P29 (T) as opposed to P25 (T), P28 (T) P29 (A) for H. contortus and H. placei(Lichtenfels and Pilitt, 2000; Mochizuki et al., 2006). Haemonchus placei (homozygous G at rDNA ITS-2 P24) was not identified from any of the small or large ruminant hosts examined from southern India (Fig. 2.1, Supplementary Table S2.3). . ...
... Haemonchus spp. commonly recognized as barber's pole worm, cause haemonchosis and are found in the abomasa of large and small ruminants worldwide (Lichtenfels & Pilitt, 2000;Achi et al., 2003). Two major species have the greatest veterinary importance, namely Haemonchus contortus and Haemonchus placei. ...
... contortus, H. placei and H. similis) occurring in naturally infected goats and sheep (Le Jambre & Whitlock, 1968;Jacquiet et al., 1995;Achi et al., 2003;Kumsa et al., 2008;Gharamah et al., 2011;Santos et al., 2014;Vadlejch et al., 2014) while synlophe or cuticular ridge patterns presenting on the body of parasite are one of the most useful characters used for identifying male and female Haemonchus spp. (Lichtenfels et al., 1994;Lichtenfels & Pilitt, 2000) and also has been applied for the identification of Haemonchus spp. in various areas, namely the United States (Lichtenfels et al., 1986), Malaysia (Rahman & Abd Hamid, 2007;Gharamah et al., 2011), andBrazil (Silva et al., 2015). Moreover, in some situations when the spicule measurements have overlapping values between H. placei and H. contortus, the synlophe patterns can facilitate identification (Amarante, 2011). ...
Haemonchus spp. or barber’s pole worms are one of the most highly pathogenic nematodes of ruminants causing economic losses in livestock worldwide. The current study was a first attempt to identify Haemonchus spp. from goats in Thailand and Lao PDR. Utilizing the inexpensive tools of the discriminant function (DF) combined with synlophe patterns is fundamental for understanding their epidemiological aspects. In total, 255 randomly chosen adult male Haemonchus worms from goats in various areas in each country were identified individually. For both these countries, about 94% based on the DF values, and 99%, 98%, and 97% based on synlophe patterns in the region of the esophageal intestinal junction (EI), 4 mm from the anterior end, and at both these positions, respectively, were identified as H. contortus. Other identified specimens defined as H. placei and hybrids as well as unclassified species based on synlophe patterns were proved using polymerase chain reaction (PCR); this also included some randomly chosen H. contortus by DF and synlophe patterns. All those specimens were confirmed as H. contortus being strongly supported by some genetic evidences and UPGMA analysis. Thus, it was assumed that all specimens in the current study were H. contortus. The morphological differences of this predominant species (H. contortus) in goats between the two countries were: body length, gubernaculum length, and left spicule barb length, while almost all characters of male worms individually measured appeared to overlap, mostly in H. contortus and H. placei, which may lead to misclassification. Therefore, using the DF along with synlophe patterns can assist in increasing the accuracy of Haemonchus spp. identification from goats in some areas where funding is limited, particularly in Lao PDR. The present results revealed that synlophe patterns in the EI region seemed to be promising for the identification of Haemonchus spp., while molecular techniques are also required to address ambiguous identification with some specimens. © 2020, Malaysian Society for Parasitology. All rights reserved.
... Adult worms were harvested on necropsy from the abomasa of ruminant hosts collected from abattoirs in southern India (Tamil Nadu, Andhra Pradesh, Kerala and Karnataka) (27 populations) and from abattoirs and government farms in Pakistan (Punjab) (22 populations) ( Fig. 1, Supplementary Table S2). Following ethanol fixation, worms were examined under a dissecting microscope to determine whether they belonged either to the Haemonchus or Mecistocirrus genera based on size and gross appearance (Lichtenfels and Pilitt, 2000). Mecistocirrus is a genus within the family trichostrongylida which is predominantly reported to infect cattle parasites. ...
... For 12 sheep, eight goats, two cattle and one buffalo, all worms were identified as H. contortus (homozygous A at rDNA ITS-2 P24) (Fig. 1). For the remaining four cattle, which contained worms with the physical appearance of Mecistocirrus, the pyrosequence genotypes were consistent with a M. digitatus species identity; homozygous P25 (A), P28 (A) P29 (T) as opposed to P25 (T), P28 (T) P29 (A) for H. contortus and H. placei (Lichtenfels and Pilitt, 2000;Mochizuki et al., 2006). Haemonchus placei (homozygous G at rDNA ITS-2 P24) was not identified from any of the small or large ruminant hosts examined from southern India (Fig. 1, Supplementary Table S3). ...
The most comprehensive genetic proof of F1 hybrids between two parasitic nematode species of humans or animals in the field.•Definitive demonstration is presented that hybridization occurs between Haemonchus contortus and H. placei in the field.•New genetic markers were used to identify H. contortus, H. placei and hybrid worms.•Co-infection of H. contortus and H. placei is common in small ruminants from Pakistan.•Only H. contortus is found in small ruminants from southern India.
... Para la descripción, previamente los gusanos fueron clarifi cados en una mezcla de alcohol-fenol. El sinlophe fue estudiado en especimenes totales y en cortes transversales en diversos niveles, de acuerdo a Lichtenfels & Pilitt (2000). ...
... El adulto tiene una longevidad promedio de 1 año. Estos nemátodos fueron originariamente descritos del zebú (Bos indicus) de Ceylán y han sido introducidos en América con los bóvidos procedentes de Asia, actualmente se encuentran ampliamente distribuidos en centro y Sudamérica donde las condiciones ecológicas favorecen su desarrollo y dinámica poblacional (Fernando, 1965;Lichtenfels and Pilitt, 2000). En el Perú, en el año 1984 mediante ley se declaró de interés nacional el desarrollo de la ganadería de bovinos, cebuinos, bubalinos entre otros, debido a la demanda de productos de origen animal, lo que posiblemente ha permitido la introducción de éste y otros parásitos. ...
In this paper, Mecistocirrus digitatus (Linstow, 1906) Railliet and Henry, 1012 a nematode Trichostrongylidae is reported in the fi rst time from Loreto, Peru.
... Varying degrees of morphological variations within and between different species of Haemonchus were reported in the past, which made accurate species identification challenging as well as time consuming [22]. In case of adults of subfamily Haemonchinae, the most reliable differences are in the patterns of longitudinal cuticular ridges of the synlophe and in chromosomal morphology [22,27]. The observations pertaining to third stage larvae of H. contortus in the present study were in concordance to the findings of van Wyk and coauthors [28]. ...
In the present study, molecular identification and genotypic characterization of H. contortus was carried out targeting 28S-18S rRNA intergenic spacer. Faecal samples of Gaddi goats were collected and subjected to qualitative screening. The samples exhibiting the presence of strongyle type eggs were introduced to faecal culturing. The larvae retrieved were molecularly confirmed as of H. contortus species and the phylogenetics was performed. For the estimation of evolutionary divergence in between the present study isolates with the GenBank archived sequences, maximum composite likelihood model was employed. Nucleotide and haplotype diversity indices and Fu’s Fs were also estimated. Approximately 260 bp size amplicons retrieved were confirmatory for the presence of H. contortus species. Phylogenetic analysis also accentuated that present parasite isolates were of H. contortus only. The nucleotide diversity (π) obtained was 0.06696, whereas, haplotype diversity was 0.92549 [95% CI: 0.77778-1.0000]. In between the isolates, Fu's Fs statistic value was positive (1.566), evidencing a deficiency of alleles, which would have happened due to recent population bottleneck. The recovered representative sequences were deposited in GenBank under the accession numbers LC600315-LC600317.To the best of our knowledge, the present study is the first report of phylogeny and haplotype diversity of H. contortus isolated from Gaddi goats of North India. The present study would also serve the basis for future detailed molecular epidemiological studies using discriminative markers for the assessment of genetic diversity in different populations of H. contortus in different hosts of the study area.
... Larval coproculture and morphological identification of L3 larvae takes 7-14 days, requires specialist expertise and is subject to inaccuracy due to species-specific culture biases. It is often not performed for routine clinical diagnosis and is very time consuming when applied to large-scale research and surveillance studies (Coles et al., 1992(Coles et al., , 2006Lichtenfels and Pilitt, 2000;McMurtry et al., 2000;Van Wyk et al., 2004;Amarante, 2011;Barrère et al., 2013;Ljungström et al., 2018). Real-time PCR-based and ddPCR approaches are more accurate but require careful optimisation and validation between laboratories for accurate quantitation. ...
A lack of quantitative information on the species composition of parasite communities present in fecal samples is a major limiting factor for the sensitivity, accuracy and interpretation of the diagnostic tests commonly used to assess anthelmintic efficacy and resistance. In this paper, we investigate the ability of ITS-2 rDNA nemabiome metabarcoding to enhance fecal egg count reduction testing by providing information on the effect of drug treatments on individual parasite species. Application of ITS-2 rDNA nemabiome metabarcoding to fecal samples from ewes from over 90 flocks across western Canada revealed high gastrointestinal nematode infection intensities in many flocks with Haemonchus contortus being the most abundant species followed by Teladorsagia circumcincta and then Trichostrongylus colubriformis. Integration of ITS-2 rDNA nemabiome metabarcoding with pre-and post-treatment fecal egg counting revealed consistently poor efficacy of producer-applied ivermectin and benzimidazole treatments against H. contortus, but much better efficacy against T. circumcincta and T. colubriformis, except for in a small number of flocks. Integration of nemabiome ITS-2 rDNA metabarcoding with Fecal Egg Count Reduction Tests (FECRT), undertaken on farm visits, confirmed that ivermectin and fen-bendazole resistance is widespread in H. contortus but is currently less common in T. circumcincta and T. colubriformis in western Canada. FECRT/nemabiome testing did not detect moxidectin resistance in any GIN species but suggested the early emergence of levamisole resistance specifically in T. circumcincta. It also revealed that although poor efficacy to closantel was relatively common, based on total fecal egg counts, this was due to its narrow spectrum of activity rather than the emergence of anthelmintic resistance. This study illustrates the value of ITS-2 rDNA nemabiome metabarcoding to improve fecal egg count resistance testing, perform large-scale anthelmintic resistance surveillance and direct more targeted rational anthelmintic use.
... Initial development of reliable means for the morphological identification of species and primarily limited to parasites circulating in domesticated hosts emerged through studies of the synlophe. Criteria for identification included the pattern of cuticular ridges, their numbers, and the extent or distribution on the body of male and female nematodes as revealed in cross-section or in examination of whole mounted specimens (Durette-Desset, 1983;Lichtenfels and Pilitt, 2000;Lichtenfels et al., 1986Lichtenfels et al., , 1994Lichtenfels et al., , 2002. For example, transverse sections at the level of the esophagealeintestinal junction reveal the presence of 30 ridges in H. contortus and 34 in H. placei . ...
Diagnosis is often equated with identification or detection when discussing parasitic diseases. Unfortunately, these are not necessarily mutually exclusive activities; diseases and infections are generally diagnosed and organisms are identified. Diagnosis is commonly predicated upon some clinical signs; in an effort to determine the causative agent, identification of genera and species is subsequently performed. Both identification and diagnosis play critical roles in managing an infection, and involve the interplay of direct and indirect methods of detection, particularly in light of the complex and expanding problem of drug-resistance in parasites. Accurate and authoritative identification that is cost- and time-effective, based on structural and molecular attributes of specimens, provides a foundation for defining parasite diversity and changing patterns of geographical distribution, host association and emergence of disease. Most techniques developed thus far have been grounded in assumptions based on strict host associations between Haemonchus contortus and small ruminants, that is, sheep and goats, and between Haemonchus placei and bovids. Current research and increasing empirical evidence of natural infections in the field demonstrates that this assumption misrepresents the host associations for these species of Haemonchus. Furthermore, the capacity of H. contortus to utilize a considerably broad spectrum of ungulate hosts is reflected in our understanding of the role of anthropogenic forcing, the ‘breakdown’ of ecological isolation, global introduction and host switching as determinants of dis- tribution. Nuanced insights about distribution, host association and epidemiology have emerged over the past 30 years, coincidently with the development of increasingly robust means for parasite identification. In this review and for the sake of argument, we would like to delineate the diagnosis of haemonchosis from the identification of the specific pathogen. As a foundation for exploring host and parasite biology, we will examine the evolution of methods for distinguishing H. contortus from other com- mon gastrointestinal nematodes of agriculturally significant and free-ranging wild ru- minants using morphological, molecular and/or immunological methods for studies at the species and genus levels
... Не выявив существенных различий в развитии описанных выше личинок гемонхов и не установив достоверных видовых различий у половозрелых гемонхов, полученных от разных хозяев, ряд авторов [5,37,39,50,51] Кроме того, имеется ряд работ, посвященных изучению морфологических и ультраструктурных строений гемонхов мелкого и крупного рогатого скота [66,67,69,75,76,93,101,107,114,116,118,119,130,132,133,134,135,162,165,183,199]. D.A. Wharton [195] описаны ультраструктурные изменения инвазионных личинок H. contortus, связанных с их линькой. ...
В монографии изложены результаты морфологических и молекулярно-генетических исследований и выяснены валидность двух видов гемонхов-Haemonchus contortus и Haemonchus placei паразитирующих у овец и крупного рогатого скота. При сравнении нуклеотидных последовательностей ITS2 участков гена рибосомальной ДНК между Н. contortus и H. placei обнаружено различие 2,6 %, что показывает их различия. Выяснены эколого-функциональные взаимоотношения рода Haemonchus в системе «паразит–хозяин». В сравнительном аспекте изучено аэробное и тканевое дыхание нематод Haemonchus contortus и Parabronema skrjabini и определена активность ферментов дыхательной цепи митохондрии. Проведен мониторинг эпизоотического процесса при гемонхозе животных и оптимизированы методы и принципы профилактики.
The monograph presents the results of morphological and molecular genetic studies and elucidates the validity of two species of haemonchus: Haemonchus contortus and Haemonchus placei parasitizing in sheep and cattle. When comparing the nucleotide sequences of ITS2 regions of the ribosomal DNA gene between H. contortus and H. placei, a difference of 2.6% was found, this shows their differences. The ecological and functional relationships of the genus Haemonchus in the “parasite – host” system have been determined. In a comparative aspect, the aerobic and tissue respiration of the nematodes Haemonchus contortus and Parabronema skrjabini was studied and the activity of mitochondrial respiratory chain enzymes was determined. The epizootic process was monitored during animal haemonchosis and the methods and principles of prevention were optimized.
... Following ethanol fixation, worms were examined under a dissecting microscope to determine whether they belonged either to the Haemonchus genera based on size and gross appearance (Lichtenfels et al., 2000). Species identity was subsequently confirmed by molecular methods as described below. ...
... Initial development of reliable means for the morphological identification of species and primarily limited to parasites circulating in domesticated hosts emerged through studies of the synlophe. Criteria for identification included the pattern of cuticular ridges, their numbers, and the extent or distribution on the body of male and female nematodes as revealed in cross-section or in examination of whole mounted specimens (Durette-Desset, 1983;Lichtenfels and Pilitt, 2000;Lichtenfels et al., 1986Lichtenfels et al., , 1994Lichtenfels et al., , 2002. For example, transverse sections at the level of the esophagealeintestinal junction reveal the presence of 30 ridges in H. contortus and 34 in H. placei . ...
Diagnosis is often equated with identification or detection when discussing parasitic diseases. Unfortunately, these are not necessarily mutually exclusive activities; diseases and infections are generally diagnosed and organisms are identified. Diagnosis is commonly predicated upon some clinical signs; in an effort to determine the causative agent, identification of genera and species is subsequently performed. Both identification and diagnosis play critical roles in managing an infection, and involve the interplay of direct and indirect methods of detection, particularly in light of the complex and expanding problem of drug-resistance in parasites. Accurate and authoritative identification that is cost- and time-effective, based on structural and molecular attributes of specimens, provides a foundation for defining parasite diversity and changing patterns of geographical distribution, host association and emergence of disease. Most techniques developed thus far have been grounded in assumptions based on strict host associations between Haemonchus contortus and small ruminants, that is, sheep and goats, and between Haemonchus placei and bovids. Current research and increasing empirical evidence of natural infections in the field demonstrates that this assumption misrepresents the host associations for these species of Haemonchus. Furthermore, the capacity of H. contortus to utilize a considerably broad spectrum of ungulate hosts is reflected in our understanding of the role of anthropogenic forcing, the ‘breakdown’ of ecological isolation, global introduction and host switching as determinants of distribution. Nuanced insights about distribution, host association and epidemiology have emerged over the past 30 years, coincidently with the development of increasingly robust means for parasite identification. In this review and for the sake of argument, we would like to delineate the diagnosis of haemonchosis from the identification of the specific pathogen. As a foundation for exploring host and parasite biology, we will examine the evolution of methods for distinguishing H. contortus from other common gastrointestinal nematodes of agriculturally significant and free-ranging wild ruminants using morphological, molecular and/or immunological methods for studies at the species and genus levels.
... Adult worms were harvested on necropsy from the abomasa of ruminant hosts collected from abattoirs in Punjab province of Pakistan (4 populations) ( Table 1). Following ethanol fixation, worms were examined under a dissecting microscope to determine whether they belongs to Haemonchus genera based on size and gross appearance (Lichtenfels and Pilitt, 2000). Species identity was subsequently confirmed by molecular methods as described below. ...
The large stomach worm, Haemonchus, commonly known as the barber’s pole worm, is a blood sucking nematode found in the abomasa of small and large ruminants. Allele-specific amplification of the rDNA internal transcribed spacer-2 (ITS-2) sequences was performed from the total of 78 individual adult worms to screen H. placei at species level, which is the significant diagnostic tool to identify this major economically important species. Further full sequences analysis of the ITS-2 region revealed that there are 4 sites shows intraspecific variations at position 65,111, 125 and 148. For instance this study is the first documented report of intraspecific genetic variations in the rDNA ITS-2 sequences of H. placei from cattle in Pakistan and the results shows that H. placei is genetically different from the isolates studied previously. However detailed and large size samples strategy will be required to identify the co-infection and interspecies hybridization between H. placei and Haemonchus contortus in cattle.
Keywords: Haemonchus placei, rDNA ITS-2, Pakistan
Abomasal nematodes (Ostertagiinae: Trichostrongyloidea), representing a previously unrecognized genus and species, were discovered in kob (Kobus kob) and kongoni (hartebeest) (Alcelaphus buselaphus jacksoni) from Uganda during surveys of ungulate parasites in the 1960s. Robustostrongylus aferensis gen. nov. et sp. nov. is characterized by a ventriculus-like, bilobed valve at the junction of the esophagus and intestine, a synlophe with unusually robust ridges, cervical papillae and excretory pore situated posterior to the mid-length of the esophagus, a unique body form and large diameter in males and females, a relatively anterior position for the vulva, and strongly convoluted and spiraled ovarian tracks in females. Bursal structure is 2-1-2, with subequal Rays 2/3, strongly reduced and robust Rays 8, and relatively narrow Rays 9/10 contained within a reduced, laterally inflated dorsal lobe. Spicules are filamentous and tripartite; the gubernaculum is cryptic, alate, and heart-shaped in the anterior. Robustostrongylus aferensis, with narrow filamentous spicules that trifurcate distally near 80%, paired arcuate "0" papillae that terminate in bulbous expansions, and a reduced dorsal lobe and ray most closely resembles species of Longistrongylus. A suite of unique characters, consistent in males and females, however, unequivocally distinguishes specimens of R. aferensis from all ostertagiines with either a 2-1-2 or 2-2-1 bursal pattern. Among 15 genera of the Ostertagiinae in the global fauna, 5 are entirely limited in distribution to Africa, including Africanastrongylus, Hamulonema, Longistrongylus, Pseudomarshallagia, and Robustostrongylus gen. nov.; species among 5 additional genera, including Cervicaprastrongylus, Hyostrongylus, Marshallagia, Ostertagia, and Teladorsagia, also occur in Africa, but they are represented as mosaics, with diversity centered in Eurasia or the Holarctic.
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