BACKGROUND: Cercarial dermatitis (CD), or swimmer's itch, is a water-borne allergic skin reaction caused by the penetration of the larval stages of bird schistosomes (cercariae) into the skin. Members of the genus Trichobilharzia are the primary causative agents of CD worldwide. Due to the increasing number of cases, CD is regarded as a (re)emerging disease. Outbreaks in recreational waters can significantly impact public health and local economies. Environmental monitoring of Trichobilharzia is crucial for outbreak prediction and public health management. However, conventional methods, such as cercarial shedding and snail dissections, are labour-intensive and lack sensitivity. To overcome these limitations, we present a molecular toolkit that combines loop-mediated isothermal amplification (LAMP), quantitative polymerase chain reaction (qPCR), and multiplex PCR for rapid, sensitive, and accurate detection and identification of Trichobilharzia spp. from various biological samples. METHODS: Tricho-LAMP and Tricho-qPCR were designed and optimised for Trichobilharzia DNA detection. A multiplex PCR assay was also developed and optimised to identify the three main species causing CD in Europe (Trichobilharzia franki, T. szidati, and T. regenti). RESULTS: Tricho-LAMP specifically detected T. regenti and T. franki at 10-3 ng, and T. szidati at 10-2 ng per reaction with genomic DNA. Using gBlocks synthetic DNA, Tricho-LAMP achieved 100% amplification at 10,000 copies and 85% amplification at 1000 copies, with decreasing success at lower concentrations. Tricho-qPCR showed the highest sensitivity, detecting all species down to 10-4 ng per reaction and showing a limit of detection at 10 copies of synthetic DNA in the reaction. Multiplex PCR allowed reliable species differentiation via gel electrophoresis of the PCR products, but the assay had the lowest sensitivity. CONCLUSIONS: We provide a molecular toolkit consisting of LAMP, qPCR, and multiplex PCR. By exhibiting high sensitivity, Tricho-LAMP and Tricho-qPCR assays are potentially suitable for environmental DNA (eDNA)-based environmental monitoring of bird schistosomes, by both researchers and public health authorities. Multiplex PCR can be used for species determination without the need for further sequencing.

• Klíčová slova
• Trichobilharzia, Bird schistosomes, Cercarial dermatitis, Detection, LAMP, Monitoring, Multiplex PCR, qPCR,
• MeSH
• diagnostické techniky molekulární * metody   MeSH
• DNA helmintů genetika   MeSH
• hlemýždi parazitologie   MeSH
• infekce červy třídy Trematoda * diagnóza   parazitologie   veterinární   MeSH
• kvantitativní polymerázová řetězová reakce * metody   MeSH
• multiplexová polymerázová řetězová reakce * metody   MeSH
• ptáci parazitologie   MeSH
• Schistosomatidae * genetika   izolace a purifikace   klasifikace   MeSH
• senzitivita a specificita MeSH
• techniky amplifikace nukleových kyselin * metody   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA helmintů MeSH

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 schistosomes are of great veterinary importance. The order Diplostomida is also rich in species parasitizing other major taxa of vertebrates. The "Aporocotylidae" sensu lato are pathogenic in fish, "Spirorchiidae" sensu lato in reptiles. All these flukes have two-host life cycles, with asexually reproducing larvae usually in mollusks and occasionally in annelids, and adults usually live in the blood vessels of their vertebrate hosts. Pathology is frequently associated with inflammatory reactions to eggs trapped in various tissues/organs. On the other hand, the representatives of Diplostomidae and Strigeidae have three- or four-host life cycles in which vertebrates often serve not only as definitive but also as intermediate or paratenic hosts. Pathology is usually associated with migration of metacercariae and mesocercariae within the host tissues. The impact of these trematode infections on both farm and wild animals may be significant.

• Klíčová slova
• Aporocotylidae, Blood flukes, Diplostomidae, Sanguinicolidae, Schistosoma, Schistosomatidae, Skin penetration, Spirorchiidae, Strigeidae, Trematodes,
• MeSH
• infekce červy třídy Trematoda * parazitologie   veterinární   MeSH
• interakce hostitele a parazita MeSH
• lidé MeSH
• Schistosomatidae genetika   MeSH
• stadia vývoje MeSH
• Trematoda fyziologie   patogenita   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

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 water snails are the intermediate, and waterfowl are the final hosts. The study aimed to conduct a molecular and phylogenetic analysis of Trichobilharzia species occurring in recreational waters in North-Eastern Poland. METHODOLOGY: The study area covered three water bodies (Lake Skanda, Lake Ukiel, and Lake Tyrsko) over the summer of 2021. In total, 747 pulmonate freshwater snails (Radix spp., Lymnaea stagnalis) were collected. Each snail was subjected to 1-2 h of light stimulation to induce cercarial expulsion. The phylogenetic analyses of furcocercariae were based on the partial sequence of the ITS region (ITS1, 5.8S rDNA, ITS2 and 28SrDNA). For Radix spp. phylogenetic analyses were based on the ITS-2 region. RESULTS: The prevalence of the Trichobilharzia species infection in snails was 0.5%. Two out of 478 (0.4%) L. stagnaliswere found to be infected with Trichobilharzia szidati. Moreover, two out of 269 (0.7%) snails of the genus Radix were positive for schistosome cercariae. Both snails were identified as Radix auricularia. One of them was infected with Trichobilharzia franki and the other with Trichobilharzia sp. CONCLUSIONS: Molecular identification of avian schistosome species, both at the intermediate and definitive hosts level, constitutes an important source of information on a potential threat and prognosis of local swimmer's itch occurrence, and helps to determine species diversity in a particular area.

• Klíčová slova
• Avian schistosomes, Cercariae, Cercarial dermatitis, Trichobilharzia,
• MeSH
• DNA helmintů genetika   MeSH
• fylogeneze * MeSH
• hlemýždi parazitologie   MeSH
• infekce červy třídy Trematoda parazitologie   veterinární   epidemiologie   MeSH
• jezera parazitologie   MeSH
• lidé MeSH
• Schistosomatidae * genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Polsko epidemiologie   MeSH
• Názvy látek
• DNA helmintů MeSH

Phenotypic polymorphism is a commonly observed phenomenon in nature, but extremely rare in free-living stages of parasites. We describe a unique case of somatic polymorphism in conspecific cercariae of the bird schistosome Trichobilharzia sp. "peregra", in which two morphs, conspicuously different in their size, were released from a single Radix balthica snail. A detailed morphometric analysis that included multiple morphological parameters taken from 105 live and formalin-fixed cercariae isolated from several naturally infected snails provided reliable evidence for a division of all cercariae into two size groups that contained either large or small individuals. Large morph (total body length of 1368 and 1339 μm for live and formalin-fixed samples, respectively) differed significantly nearly in all morphological characteristics compared to small cercariae (total body length of 976 and 898 μm for live and formalin samples, respectively), regardless of the fixation method. Furthermore, we observed that small individuals represent the normal/commonly occurring phenotype in snail populations. The probable causes and consequences of generating an alternative, much larger phenotype in the parasite infrapopulation are discussed in the context of transmission ecology as possible benefits and disadvantages facilitating or preventing the successful completion of the life cycle.

• Klíčová slova
• Trichobilharzia, bird schistosome, cercariae, phenotype, polymorphism, trematodes,
• Publikační typ
• časopisecké články MeSH

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 ('visceral fluke') and T. regenti ('neurotropic fluke') in their avian host. We studied the larvae of each species before they enter (cercariae) and as they migrate (schistosomules) through distinct tissues in their avian (duck) host. Cercariae of both species were enriched for pathways or molecules associated predominantly with carbohydrate metabolism, oxidative phosphorylation and translation of proteins linked to ribosome biogenesis, exosome production and/or lipid biogenesis. Schistosomules of both species were enriched for pathways or molecules associated with processes including signal transduction, cell turnover and motility, DNA replication and repair, molecular transport and/or catabolism. Comparative informatic analyses identified molecular repertoires (within, e.g., peptidases and secretory proteins) in schistosomules that can broadly degrade macromolecules in both T. szidati and T. regenti, and others that are tailored to each species to selectively acquire nutrients from particular tissues through which it migrates. Thus, this study provides molecular evidence for distinct modes of nutrient acquisition between the visceral and neurotropic flukes of birds.

• MeSH
• cerkárie klasifikace   genetika   patogenita   MeSH
• DNA helmintů klasifikace   genetika   MeSH
• fylogeneze * MeSH
• kachny genetika   parazitologie   MeSH
• lidé MeSH
• nemoci ptáků genetika   parazitologie   MeSH
• ptáci genetika   parazitologie   MeSH
• Schistosomatidae genetika   patogenita   MeSH
• schistosomóza genetika   parazitologie   MeSH
• Trematoda klasifikace   genetika   patogenita   MeSH
• výpočetní biologie MeSH
• živiny MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA helmintů MeSH

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 areas. Although the symptoms of CD are generally known, the data on immune response in human patients are sporadic and incomprehensive. In the present study, we attempted to correlate the symptoms, personal history, and time course of CD in human patients with differential cell counts, dynamics of selected cytokines, and dynamics and quality of antibody response. By a systematic follow-up, we obtained a uniquely complex dataset from ten persons accidentally and concurrently infected by the same parasite species in the same locality. The onset of CD was significantly faster, and the symptoms were heavier in participants with a history of CD if compared to naive ones, who, however, also developed some of the symptoms. The repeatedly infected persons had elevated proportion of eosinophils 1 week post exposure (p.e.) and a stronger specific IgG but not IgM response, whereas specific IgE response was not observed. Increased serum levels of IL-4 occurred 1 and 3 week(s) p.e. in all participants. There was high variability in individual immunoblot patterns of IgG response, and no antigen with a universal diagnostic potential was confirmed. The presented analyses suggested that a complex approach can improve the accuracy of the diagnosis of CD, but component data should be interpreted carefully.

• Klíčová slova
• Allergy, Diagnosis, Immunity, Schistosome, Skin, Trichobilharzia,
• MeSH
• dermatitida imunologie   parazitologie   MeSH
• dospělí MeSH
• epidemický výskyt choroby MeSH
• imunoglobulin E krev   MeSH
• imunoglobulin G krev   MeSH
• imunoglobulin M krev   MeSH
• infekce červy třídy Trematoda diagnóza   imunologie   parazitologie   MeSH
• interleukin-4 krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• následné studie MeSH
• protilátky protozoální krev   MeSH
• průzkumy a dotazníky MeSH
• rybníky parazitologie   MeSH
• Schistosomatidae imunologie   MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• IL4 protein, human MeSH Prohlížeč
• imunoglobulin E MeSH
• imunoglobulin G MeSH
• imunoglobulin M MeSH
• interleukin-4 MeSH
• protilátky protozoální MeSH

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 snail periphyton grazing. Here, we used four different freshwater snail-trematode systems to test whether a general pattern can be detected for the impact of trematode infections on snail periphyton grazing. In our experimental systems, mass-specific periphyton grazing rates of infected snails were higher, lower, or similar to rates of non-infected conspecifics, suggesting that no general pattern exists. The variation across studied snail-trematode systems may result from differences on how the parasite uses the resources of the snail and thus affects their energy budget. Trematode infections can significantly alter the grazing rate of snails, where, depending on the system, the mass-specific grazing rate can double or halve. This underlines both, the high ecological relevance of trematodes and the need for comprehensive studies at the species level to allow an integration of these parasite-host interactions into aquatic food web concepts.

• Klíčová slova
• Freshwater snails, Grazing rates, Host–parasite interaction, Periphyton, Trematodes,
• MeSH
• ekologie MeSH
• ekosystém MeSH
• hlemýždi parazitologie   MeSH
• infekce červy třídy Trematoda parazitologie   MeSH
• interakce hostitele a parazita fyziologie   MeSH
• perifyton * MeSH
• potravní řetězec MeSH
• přijímání potravy fyziologie   MeSH
• sladká voda parazitologie   MeSH
• Trematoda izolace a purifikace   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Nasal bird schistosomes can cause bilharziosis in birds and have the potential to cause swimmer's itch in humans. We determined the prevalence of bird schistosomes in 106 mallards (Anas plathyrhynchos) from 11 water sources in Germany from 2014. Dissections were performed focusing on parasitic infections of the neural system. Infections with Trichobilharzia regenti (Horák et al. 1998) were found in 21% of the birds (n = 22), whereas Bilharziella polonica (Kowalewski 1895) were found between the brain membranes (meninges) and the brain, in the spinal cord or in the intestine of 12% of the mallards (n = 13). No significant influence of sex, age, and body condition between infected and non-infected animals was observed. Our study provides the first description of B. polonica from the neural system of birds and provides an epidemiological understanding of a parasite of human health concern.

• Klíčová slova
• Bilharziella polonica, Bird schistosomes, Mallard, Trichobilharzia regenti,
• MeSH
• divoká zvířata parazitologie   MeSH
• infekce červy třídy Trematoda parazitologie   veterinární   MeSH
• kachny parazitologie   MeSH
• lidé MeSH
• nemoci ptáků parazitologie   MeSH
• nervový systém parazitologie   MeSH
• Schistosoma genetika   izolace a purifikace   fyziologie   MeSH
• Schistosomatidae genetika   izolace a purifikace   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Německo MeSH

Digenean trematodes are common and abundant in aquatic habitats and their free-living larvae, the cercariae, have recently been recognized as important components of ecosystems in terms of comprising a significant proportion of biomass and in having a potentially strong influence on food web dynamics. One strategy to enhance their transmission success is to produce high numbers of cercariae which are available during the activity peak of the next host. In laboratory experiments with 13 Lymnaea stagnalis snails infected with Trichobilharzia szidati the average daily emergence rate per snail was determined as 2,621 cercariae, with a maximum of 29,560. During a snail's lifetime this summed up to a mass equivalent of or even exceeding the snail's own body mass. Extrapolated for the eutrophic pond where the snails were collected, annual T. szidati biomass may reach 4.65 tons, a value equivalent to a large Asian elephant. Emission peaks were observed after the onset of illumination, indicating emission synchronizing with the high morning activities of the definitive hosts, ducks. However, high cercarial emission is possible throughout the day under favorable lightning conditions. Therefore, although bird schistosomes, such as T. szidati constitute only a fraction of the diverse trematode communities in the studied aquatic ecosystem, their cercariae can still pose a considerable risk for humans of getting cercarial dermatitis (swimmer's itch) due to the high number of cercariae emitted from infected snails.

• MeSH
• biomasa MeSH
• cerkárie růst a vývoj   MeSH
• chronobiologické jevy MeSH
• ekosystém MeSH
• Lymnaea parazitologie   fyziologie   MeSH
• neparametrická statistika MeSH
• plavání MeSH
• Schistosomatidae růst a vývoj   MeSH
• stadia vývoje MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

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 hosts, almost nothing is known about the molecular aspects of how this fluke invades its hosts, migrates in host tissues and how it interacts with its hosts' immune system. Here, we explored selected aspects using a transcriptomic-bioinformatic approach. To do this, we sequenced, assembled and annotated the transcriptome representing two consecutive life stages (cercariae and schistosomula) of T. regenti involved in the first phases of infection of the avian host. We identified key biological and metabolic pathways specific to each of these two developmental stages and also undertook comparative analyses using data available for taxonomically related blood flukes of the genus Schistosoma. Detailed comparative analyses revealed the unique involvement of carbohydrate metabolism, translation and amino acid metabolism, and calcium in T. regenti cercariae during their invasion and in growth and development, as well as the roles of cell adhesion molecules, microaerobic metabolism (citrate cycle and oxidative phosphorylation), peptidases (cathepsins) and other histolytic and lysozomal proteins in schistosomula during their particular migration in neural tissues of the avian host. In conclusion, the present transcriptomic exploration provides new and significant insights into the molecular biology of T. regenti, which should underpin future genomic and proteomic investigations of T. regenti and, importantly, provides a useful starting point for a range of comparative studies of schistosomatids and other trematodes.

• MeSH
• biologická adaptace * MeSH
• interakce hostitele a patogenu * MeSH
• kachny parazitologie   MeSH
• metabolické sítě a dráhy genetika   MeSH
• molekulární sekvence - údaje MeSH
• Schistosomatidae genetika   růst a vývoj   MeSH
• sekvenční analýza DNA MeSH
• stadia vývoje MeSH
• stanovení celkové genové exprese * MeSH
• výpočetní biologie * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH