About
292
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Introduction
See our team website:
https://www.helminthology.cz
See my personal website:
https://www.petrhorak.eu
Current institution
Additional affiliations
March 1990 - present
Position
- Professor
Description
- We are focused on parasitic helminths of humans and animals. Experimental parasitology (molecular and biochemical parasitology, immunology of parasitic diseases) is supplemented with field studies (transmission, taxonomy and diagnosis).
March 1990 - present
August 1988 - March 1989
Education
May 2005 - May 2005
May 1999 - May 1999
October 1990 - June 1996
Publications
Publications (292)
Skin uses interdependent cellular networks for barrier integrity and host immunity, but most underlying mechanisms remain obscure. Herein, we demonstrate that the human parasitic helminth Schistosoma mansoni inhibited pruritus evoked by itch-sensing afferents bearing the Mas-related G-protein-coupled receptor A3 (MrgprA3) in mice. MrgprA3 neurons c...
Toxocara canis larvae are one of the most overlooked agents of nervous system infection in paratenic hosts. Previous studies in mouse models have shown that infection with various (mainly high) numbers of larvae leads to neurobehavioral disturbances and pathological changes. Our study investigated whether the infection with low and moderate numbers...
Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomosis (schistosomiasis) affecting more than 200 million people in tropical and subtropical countries, and infections of mammals and birds by animal sc...
Background
In Europe, avian schistosomes of the genus Trichobilharzia are the most common etiological agents involved in human cercarial dermatitis (swimmer’s itch). Manifested by a skin rash, the condition is caused by an allergic reaction to cercariae of nonhuman schistosomes. Humans are an accidental host in this parasite’s life cycle, while wat...
During late summer in 1995 to 1997, repeated outbreaks of maculopapular skin eruptions were noted on the legs of children after wading in the pond in the Family Park in Laugardalur, Reykjavík, Iceland. Clinical symptoms developing on the legs resembled those of cercarial dermatitis. An examination of Lymnaea peregra snails from this pond and from t...
Cancer is one of the leading causes of death, with an estimated 19.3 million new cases and 10 million deaths worldwide in 2020 alone. Approximately 2.2 million cancer cases are attributed to infectious diseases, according to the World Health Organization (WHO). Despite the apparent involvement of some parasitic helminths (especially trematodes) in...
Cancer is still one of the leading causes of death, with an estimated 19.3 million new cases every year. Our paper presents the tumor-suppressing effect of Taenia crassiceps and Mesocestoides corti on B16F10 melanoma, the intraperitoneal application of which followed the experimental infection with these tapeworms, resulting in varying degrees of e...
The incidences of multiple sclerosis have risen worldwide, yet neither the trigger nor efficient treatment is known. Some research is dedicated to looking for treatment by parasites, mainly by helminths. However, little is known about the effect of helminths that infect the nervous system. Therefore, we chose the neurotropic avian schistosome Trich...
Toxocara canis, a gastrointestinal parasite of canids, is also highly prevalent in many paratenic hosts, such as mice and humans. As with many other helminths, the infection is associated with immunomodulatory effects, which could affect other inflammatory conditions including autoimmune and allergic diseases. Here, we investigated the effect of To...
There is a great need to understand the impact of complex communities on the free-living parasite stages that are part of them. This task becomes more complex as nonnative species emerge, changing existing relationships and shaping new interactions in the community. A relevant question would be: Can the coexistence of nontarget snails with the targ...
Helminth neuroinfections represent serious medical conditions, but the diversity of the host-parasite interplay within the nervous tissue often remains poorly understood, partially due to the lack of laboratory models. Here, we investigated the neuroinvasion of the mouse spinal cord by Trichobilharzia regenti (Schistosomatidae). Active migration of...
Schistosome invasive stages, cercariae, leave intermediate snail hosts, penetrate the skin of definitive hosts, and transform to schistosomula which migrate to the final location. During invasion, cercariae employ histolytic and other bioactive products of specialized holocrine secretory cells – postacetabular (PA) and circumacetabular (CA) penetra...
Schistosome invasive stages, cercariae, leave intermediate snail hosts, penetrate the skin of definitive hosts, and transform to schistosomula migrating to final localization. During invasion, cercariae employ histolytic and other bioactive products of specialized holocrine secretory cells – postacetabular (PA) and circumacetabular (CA) penetration...
Due to the increased prevalence of human infections with bird schistosome larvae (cercarial dermatitis) associated with bathing in Danish lakes, a nationwide survey of infected intermediate host snails was conducted in 2018–2020. Pulmonate snails (10,225 specimens) were collected from 39 freshwater lakes (in the four major geographic regions in Den...
Background:
Avian schistosomes, the causative agents of human cercarial dermatitis (or swimmer's itch), die in mammals but the mechanisms responsible for parasite elimination are unknown. Here we examined the role of reactive nitrogen species, nitric oxide (NO) and peroxynitrite, in the immune response of mice experimentally infected with Trichobi...
No effective method has yet been developed to prevent the threat posed by the emerging disease—cercarial dermatitis (swimmer’s itch), caused by infective cercariae of bird schistosomes (Digenea: Schistosomatidae). In our previous studies, the New Zealand mud snail— Potamopyrgus antipodarum (Gray, 1853; Gastropoda, Tateidae)—was used as a barrier be...
Aims:
Trichobilharzia regenti (Schistosomatidae) percutaneously infects birds and mammals and invades their central nervous system (CNS). Here we characterised the peripheral immune response of infected mice and showed how it was influenced by the parasite-induced inflammation in the skin and the CNS.
Methods and results:
As revealed by flow cyt...
Schistosomula (the post-infective stages) of the neurotropic schistosome Trichobilharzia regenti possess multiple isoforms of cathepsin B1 peptidase (TrCB1.1-TrCB1.6) with involvement in nutrient digestion. The comparison of substrate preferences of TrCB1.1 and TrCB1.4 showed that TrCB1.4 had a very narrow substrate specificity and after processing...
In the present study, we analyzed the morphology of three genetic types of the bird-infecting acanthocephalan Polymorphus cf. minutus (PspT1, PspT2, PspT3), mainly based on the cystacanth-stage obtained from amphipods (Gammarus fossarum, Gammarus pulex, Gammarus roeselii, Echinogammarus spp.). Males and females were pooled as there was no considera...
Antibody trapping is a recently described strategy for immune evasion observed in the
intestinal trematode Echinostoma caproni, which may aid to avoiding the host humoral
response, thus facilitating parasite survival in the presence of high levels of local
specific antibodies. Parasite-derived peptidases carry out the degradation of trapped
antibod...
Lymnaea stagnalis is a common freshwater gastropod. Importantly, the snail serves as the intermediate host for more than one hundred species of digenetic trematodes, including the avian schistosome Trichobilharzia szidati, a causative agent of cercarial dermatitis in humans. Infection of L. stagnalis by T. szidati initiates a dynamic confrontation...
Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomosis affecting more than 200 million people in tropical and subtropical countries, infections of mammals and birds by animal schistosomes are of grea...
Trichobilharzia species are parasitic flatworms (called schistosomes or flukes) that cause important diseases in birds and humans, but very little is known about their molecular biology. Here, using a transcriptomics-bioinformatics-based approach, we explored molecular aspects pertaining to the nutritional requirements of Trichobilharzia szidati (‘...
Abstract
Cercarial dermatitis (CD) is an allergic skin disease that rises in consequence of infection by invasive stages (cercariae) of trematodes of the family Schistosomatidae. CD has been considered a re-emerging disease, human cases have been reported from all continents, and tourism-threatening outbreaks occur even in frequented recreational a...
Parasitic nematodes (roundworms) and platyhelminths (flatworms) cause debilitating chronic infections of humans and animals, decimate crop production and are a major impediment to socioeconomic development. Here we report a broad comparative
study of 81 genomes of parasitic and non-parasitic worms. We have identified gene family births and hundreds...
In freshwater ecosystems, snails can significantly influence the competition between primary producers through grazing of periphyton. This activity can potentially be modified by trematodes, a large group of parasites which mostly use molluscs as the first intermediate host. Available studies, however, show contradictory effects of trematodes on sn...
Swimmer’s itch is a re-emerging human disease caused by bird schistosome cercariae, which can infect bathing or working people in water bodies. Even if cercariae fail after penetrating the human skin, they can cause dangerous symptoms in atypical mammal hosts. One of the natural methods to reduce the presence of cercariae in the environment could l...
Survival of Radix balthica infected with Trichobilharzia regenti miracidia in the presence of Potamopyrgus antipodarum
Survival of infected and non–infected Radix balthica
The database for effectiveness of parasite invasion to R. balthica at the presence of Potamopyrgus antipodarum (results of Fisher Exact Test)
Effectiveness of parasite invasion to Radix balthica in the presence of Potamopyrgus antipodarum
The discovery that mammalian neutrophils generate extracellular chromatin fibers that entrap/kill bacteria supported a new paradigm for innate immunity in animals. Similar findings in other models across diverse taxa have led to the hypothesis that the phenomenon is ancient and evolutionary conserved. Here, using a variety of synthetic (e.g. peptid...
The study was focused on the dynamics of humoral response to Toxocara canis excretory-secretory antigens (TES antigens) in mice experimentally infected by T. canis L3 larvae in different ways. In particular, we compared the effect of infection with two doses of 1000 larvae vs. repeated infections with a low number of larvae (daily infection with 10...
Background: Parasitic worms cause serious and worldwide distributed human neuroinfections, such as neurocysticercosis or cerebral toxocarosis. However, the immune processes in the affected nervous tissue (including the characterization of glial cells activities) usually remain overlooked. In our study, we explored the response of avian and murine a...
The invasive larvae (cercariae) of schistosomes penetrate the skin of their definitive hosts. During the invasion, they undergo dramatic ultrastructural and physiological transitions. These changes result in the development of the subsequent stage, schistosomulum, which migrates through host tissues in close contact with host’s immune system. One o...
Time-lapse photography of the formation of the shedding tunnel by cercaria of T. regenti.
Secretion from the penetration glands was stimulated by addition of linoleic acid and visualized by staining with lithium carmine. Frames were taken in the intervals of 30 s.
(WMV)
Cercaria of the genus Schistosoma represents a free-swimming developmental stage that to complete its life cycle must contact the mammalian skin. Thereafter, it penetrates the skin and transforms into an intravertebrate stage - the schistosomulum. Therefore, the cercaria represents an infective stage, a link between the intermediate (snail) and the...
Background
Helminth neuroinfections represent a serious health problem, but host immune mechanisms in the nervous tissue often remain undiscovered. This study aims at in vitro characterization of the response of murine astrocytes and microglia exposed to Trichobilharzia regenti which is a neuropathogenic schistosome migrating through the central ne...
Infection with Fascioloides magna (Digenea) causes serious damage to liver tissue in definitive hosts represented by ruminants, especially cervids. The distribution of F. magna includes the indigenous areas in North America, and the areas to which F. magna was introduced-Central Europe, Southeast Europe, and Italy. The North American intermediate h...
Trichobilharzia Skrjabin & Zakharov, 1920 is known as the most species-rich genus of the blood fluke family Schistosomatidae. To date, more than 40 species have been described, even though validity of some of them is questionable (Horák et al. 2002). Members of the genus use various birds as final hosts, but they attract attention mostly as causati...
To date, most molecular investigations of schistosomatids have focused principally on blood flukes (schistosomes) of humans. Despite the clinical importance of cercarial dermatitis in humans caused by Trichobilharzia regenti and the serious neuropathologic disease that this parasite causes in its permissive avian hosts and accidental mammalian host...
Summary of transcripts upregulated in the cercaria stage of Trichobilharzia regenti based on read mapping to the (consensus) transcriptome with National Center for Biotechnology Information (NCBI) annotation.
Sorted in descending based on log2-fold change of differential transcription.
(XLSX)
Summary of raw reads, trimmed reads, trimmed and normalized reads for the transcriptomic data of cercariae and schistosomula of Trichobilharzia regenti.
Results of mapping of paired, trimmed, corrected, non-normalized reads from cercariae and schistosomula to the final non-redundant transcriptome of Trichobilharzia regenti. P1—pair read 1; P2—pair...
Summary of peptidases and their inhibitors encoded in the transcriptome representing Trichobilharzia regenti, classified into families and subfamilies, with type enzyme listed in the MEROPS peptidase database.
UP—Unassigned peptidase
(XLSX)
Transcripts of Trichobilharzia regenti predicted to encode excretory/secretory (ES) proteins, annotated using the National Center for Biotechnology Information (NCBI) database.
Transcription level established based on RNA-Seq by Expectation Maximization (RSEM) analysis. Sorted in descending order based on “expected counts” for the schistosomula sta...
Summary of the classification of predicted proteins from transcriptome of cercariae and schistosomula of Trichobilharzia regenti based on homology (BLASTp; E-value ≤ 10−5) to annotated proteins in the Kyoto Encyclopedia of Genes and Genomes (KEGG) BRITE functional hierarchies database, and pathway maps for cellular and organismal functions.
(XLSX)
Summary of transcripts upregulated in the schistosomulum stage of Trichobilharzia regenti based on read mapping to (consensus) transcriptome, using National Center for Biotechnology Information (NCBI) annotation.
Sorted in descending order based on log2-fold change of differential transcription.
(XLSX)
Orphan transcripts of the combined cercaria/schistosomulum transcriptome of Trichobilharzia regenti with no homology to other trematodes and classified based on NCBI and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases.
(XLSX)
Summary of transcripts uniquely transcribed in each cercaria and schistosomulum of Trichobilharzia regenti based on read mapping to the (consensus) transcriptome.
Annotation using the National Center for Biotechnology Information (NCBI) database, and level of transcription based on RNA-Seq by Expectation Maximization (RSEM) analysis.
(XLSX)
Transcripts uniquely transcribed in either the cercaria or schistosomulum of Trichobilharzia regenti, classified using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.
(XLSX)
Summary of transcripts enriched in the cercaria stage of Trichobilharzia regenti based on Kyoto Encyclopedia of Genes and Genomes (KEGG) BRITE/pathway and gene ontology (GO) classifications.
Transcripts uniquely transcribed in the cercaria are marked with an asterisk.
(XLSX)
Summary of transcripts enriched in the schistosomulum stage of Trichobilharzia regenti based on Kyoto Encyclopedia of Genes and Genomes (KEGG) BRITE/pathway and gene ontology (GO) classifications.
Transcripts uniquely transcribed in the schistosomulum are marked with an asterisk.
(XLSX)
The nasal avian schistosome Trichobilharzia regenti spends part of its intravertebrate period of life within the central nervous system. Migration of the parasites can be accompanied by neuromotor disorders or paralysis in natural definitive hosts (ducks) and even in laboratory mammals. Cercariae are also able to penetrate human skin and induce cer...
Cercarial dermatitis (swimmer's itch) is a condition caused by infective larvae (cercariae) of a species-rich group of mammalian and avian schistosomes. Over the last decade, it has been reported in areas that previously had few or no cases of dermatitis and is thus considered an emerging disease. It is obvious that avian schistosomes are responsib...
Radix lagotis is an intermediate snail host of the nasal bird schistosome Trichobilharzia regenti. Changes in defence responses in infected snails that might be related to host-parasite compatibility are not known. This study therefore aimed to characterize R. lagotis haemocyte defence mechanisms and determine the extent to which they are modulated...
Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomiasis affecting more than 200 million people in tropical and subtropical countries, and infections of mammals and birds by animal schistosomes are of...
Fascioloides magna is a pathogenic fluke introduced to Europe ca 140 years ago. As it is spreading over the continent, new intermediate and definitive hosts might be involved in transmission of the parasite. In Europe, several studies reported potential new intermediate snail hosts (Radix spp.) for F. magna, and also several cases of fascioloidosis...
[This corrects the article , PMID: 23125918.].
Bird schistosomes, besides being responsible for bird schistosomiasis, are known as causative agents of cercarial dermatitis. Cercarial dermatitis develops after repeated contact with cercariae, mainly of the genus
Trichobilharzia
, and was described as a type I, immediate hypersensitivity response, followed by a late phase reaction. The immune res...
Lymnaeid snails of the genus Radix serve as intermediate hosts of some schistosomes and fasciolids. In Europe, delineation of species within the genus Radix is unresolved and, therefore, spectrum of snail hosts susceptible to trematode infections is under discussion. We used and compared three criteria for species delineation using snails collected...
Cercarial dermatitis (swimmer's itch) is a common non-communicable water-borne disease. It is caused by penetration of the skin by larvae (cercariae) of schistosomatid flukes and develops as a maculopapular skin eruption after repeated contacts with the parasites. The number of outbreaks of the disease is increasing, and cercarial dermatitis can th...
Parasitic liver flukes of the family Fasciolidae are responsible for major socio-economic losses worldwide. However, at present, knowledge of the fundamental molecular biology of these organisms is scant. Here, we characterize, for the first time, the transcriptome and secreted proteome of the adult stage of the 'giant liver fluke', Fascioloides ma...
Bird schistosomes have been in focus as causative agents of cercarial dermatitis of humans in the last years; however, our knowledge of their species spectrum and intermediate host specificity is still insufficient. Our study focused on bird schistosomes developing in planorbid snails that have been less studied so far. From 2001 to 2010, cercariae...
The giant liver fluke, Fascioloides magna, is of interest to wild-life managers, veterinarians and researchers, due to its unusual body size (3-10 cm), high pathogenic potential and because it is continuously spreading to new areas, especially in Europe. Annually, the number of cases of animal infections (mainly cervids and bovids) caused by this f...
Like several other bird schistosomes, neurotropic schistosome of Trichobilharzia regenti can invade also mammals, including humans. Repeated infections cause cercarial dermatitis, a skin inflammatory reaction leading to parasite elimination in non-specific mammalian hosts. However, in experimentally primo-infected mice, the worms escape from the sk...
The first author detected the nasal bird schistosome Trichobilharzia regenti in Iceland in Anas platyrhynchos in Landmannalaugar in autumn of 2003. Since then, measurements and morphological studies have been performed on fresh worms (fragments) obtained in the area from naturally infected ducks, A. platyrhynchos and Aythya marila. In the present s...
Trichobilharzia regenti (Schistosomatidae, Digenea), a parasite of birds, exhibits a unique strategy among schistosomes, having affinity to the nervous system of vertebrate hosts. Migration of parasitic stages within hosts and/or swimming of non-parasitic larvae in water environment depend on the action of body wall muscles which were studied with...
Trichobilharzia regenti and T. szidati are schistosomes that infect birds. although T. regenti/T. szidati can only complete their life cycle in specific bird hosts (waterfowl), their larvae-cercariae are able to penetrate, transform and then migrate as schistosomula in nonspecific hosts (e.g., mouse, man). Peptidases are among the key molecules pro...
1. Birds and snails are suitable hosts for many parasites, including helminths in general and trematodes in particular. Among trematodes, members of the family Schistosomatidae with two-host life cycles (snails as intermediate hosts and birds as definitive hosts) are successful and abundant pathogens. Their transmission between birds and snails in...
Larval stages (cercariae) of schistosomatid flukes represent the causative agents of swimmer's itch (cercarial dermatitis), a waterborne allergic disease. Cercariae of bird schistosomes are the most frequently reported agent. Recent studies on parasite behaviour in mammals showed that infections by cercariae can be linked to more than skin syndrome...
The neurotropic bird schistosome Trichobilharzia regenti possesses papain-like cysteine peptidases which have also been shown to be crucial enzymes in various developmental stages of the related human parasites Schistosoma spp. In this paper, we present data obtained by real-time polymerase chain reaction on the temporal distribution of transcripts...
Samples of schistosome cercariae from three different snail species (Lymnaea stagnalis, Radix auricularia and Valvata (Tropidina) macrostoma) collected from lakes in Central Finland were analyzed using molecular techniques. Based on sequences of ITS region of rDNA, the parasite isolates from L. stagnalis and R. auricularia belong to Trichobilharzia...
During the years 2002-2007, Icelandic freshwater snails and birds from different orders were examined for bird schistosomes. Only the snail Radix peregra and anatid birds proved to be infected. In total, 32 samples of bird schistosome cercariae from seven localities and four samples of adults of Anas platyrhynchos and Mergus serrator from two local...
Cercariae of bird schistosomes are traditionally considered to be very similar in their morphological characteristics. In
order to solve the problem, we tested some methods which might be suitable for cercarial differentiation. Fourteen isolates
of three Trichobilharzia species (T. szidati, T. franki, T. regenti) occurring sympatrically in Central...
Cercariae of bird schistosomes (Trichobilharzia szidati and Trichobilharzia regenti) were mechanically stimulated to transform to schistosomula and kept in different cultivation media supplemented with duck red blood cells and/or homogenized nervous tissue. The development under in vitro conditions was compared with that in vivo, using the followin...
Among human and veterinary parasitic diseases the trematodiases (e.g. schistosomiasis, fascioliasis) represent a problem of global importance with vast social, economic and public health impacts, especially in developing countries. Therefore, host-parasite (host-trematode) interactions represent a key topic in many research laboratories, and modern...
