Parasites comprise a huge part of the biodiversity on earth. However, on a local scale, not much is known about their diversity and community structure. Here, we assess the diversity of larval trematode communities in an interconnected freshwater system of the River Ruhr in Germany and analyse how the parasites are spatially and temporally distributed in the ecosystem. A total of 5347 snail hosts belonging to six species revealed a highly diverse parasite fauna with 36 trematode species. More abundant snail species harboured more species-rich trematode faunas and communities, with the two dominant snail species, Radix auricularia and Gyraulus albus, accounting for almost 90% of the trematode diversity and harbouring spatially and temporally stable parasite communities. The results highlight the important role of stable keystone host populations for trematode transmission, structure and diversity. This local trematode diversity reveals information on definitive host occurrence and trophic interactions within ecosystems.

• MeSH
• biodiverzita * MeSH
• ekosystém * MeSH
• hlemýždi parazitologie   MeSH
• interakce hostitele a parazita genetika   MeSH
• larva parazitologie   MeSH
• lidé MeSH
• populační dynamika MeSH
• řeky MeSH
• sladká voda parazitologie   MeSH
• Trematoda klasifikace   patogenita   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Německo MeSH

Swimmer's itch is a zoonotic disease caused by certain digenean trematodes, in Europe most noticeably by bird schistosomes of the genus Trichobilharzia. These parasites require waterfowl and aquatic snails as final and intermediate hosts, respectively, to complete their life cycle. Swimmer's itch occurs when the free-swimming larvae emitted from snails, the cercariae, accidentally infect humans. Here the parasites cannot complete their life cycle but can cause allergic inflammatory responses of the skin. In the context of the joint BMBF project 'Sichere Ruhr' (Safe Ruhr), which evaluates the Ruhr River as a potential bathing water, the occurrence of the causative agents of swimmer's itch in Lake Baldeney was studied. A total of 1741 snails was examined for the presence of trematode infections, including bird schistosomes. Snails infected with Trichobilharzia spp. were found at three sampling locations but showed low overall prevalences (0.6-3.0%). Based on parasite and host biology, risk factors were evaluated and discussed in the context of the potential use of Lake Baldeney as a bathing water. Although bird schistosomes only constitute a fraction of the trematode diversity occurring in natural snail populations and show low prevalence, they still pose an infection risk due to the high emission rates of cercariae from individual snail hosts. A wide variety of often interacting biotic and abiotic factors, as well as personal behaviour have an effect on the likelihood and severity of a human infection. Based on these risk factors, a number of possible preventive actions aiming at the disruption of the life cycle, or personal protective measures can be suggested. While absolute protection is impossible (unless swimming in natural waters is altogether avoided) some preventive measures can reduce the risk of human infections.

• MeSH
• hlemýždi parazitologie   MeSH
• infekce červy třídy Trematoda epidemiologie   MeSH
• jezera MeSH
• látky znečišťující vodu izolace a purifikace   MeSH
• lidé MeSH
• monitorování životního prostředí MeSH
• parazitární onemocnění kůže epidemiologie   MeSH
• plavání MeSH
• ptáci parazitologie   MeSH
• řeky MeSH
• rizikové faktory MeSH
• Trematoda izolace a purifikace   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Německo epidemiologie   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

BACKGROUND: Recent molecular studies have discovered substantial unrecognised diversity within the genus Diplostomum in fish populations in Europe and North America including three species complexes. However, data from the first intermediate host populations are virtually lacking. This study addresses the application of an integrative taxonomic approach to the cryptic species diversity of Diplostomum spp. in natural lymnaeid snail populations in Europe with a focus on the 'D. mergi' species complex. METHODS: Totals of 1,909 Radix auricularia, 349 Radix peregra, 668 Stagnicola palustris and 245 Lymnaea stagnalis were sampled at five reservoirs of the Ruhr river system in Germany and screened for infections with Diplostomum spp. Cercariae were examined and identified alive, fixed and under scanning electron microscopy. Sequences from the barcode region of the cytochrome c oxidase subunit 1 (cox1) mitochondrial gene and from the internal transcribed spacer cluster (ITS1-5.8S-ITS2) of the rRNA gene were amplified for 51 and 13 isolates, respectively. RESULTS: Detailed morphological and molecular analyses provided evidence for three named species (Diplostomum spathaceum, D. pseudospathaceum and D. parviventosum), and a further four species-level lineages ('D. mergi Lineages 2-4' and 'Diplostomum sp. Clade Q' in the lymnaeid snail populations from the Ruhr river basin. The paper provides the first descriptions of molecularly identified cercariae of D. spathaceum and of the cercariae of D. parviventosum, three lineages of the 'D. mergi' species complex and of 'Diplostomum sp. Clade Q'. CONCLUSION: The integration of molecular and morphological evidence for Diplostomum spp. achieved in this study will serve as a baseline for species identification of these important parasites of snail and fish populations and thus advance further studies on the distribution of Diplostomum spp. in Europe.

• MeSH
• biodiverzita MeSH
• fylogeneze MeSH
• hlemýždi klasifikace   parazitologie   MeSH
• infekce červy třídy Trematoda parazitologie   veterinární   MeSH
• molekulární sekvence - údaje MeSH
• nemoci ryb parazitologie   MeSH
• ryby klasifikace   parazitologie   MeSH
• Trematoda klasifikace   genetika   izolace a purifikace   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Německo MeSH
• Severní Amerika MeSH

BACKGROUND: The digenean species of Echinostoma (Echinostomatidae) with 37 collar spines that comprise the so-called 'revolutum' species complex, qualify as cryptic due to the interspecific homogeneity of characters used to differentiate species. Only five species were considered valid in the most recent revision of the group but recent molecular studies have demonstrated a higher diversity within the group. In a study of the digeneans parasitising molluscs in central and northern Europe we found that Radix auricularia, R. peregra and Stagnicola palustris were infected with larval stages of two cryptic species of the 'revolutum' complex, one resembling E. revolutum and one undescribed species, Echinostoma sp. IG. This paper provides morphological and molecular evidence for their delimitation. METHODS: Totals of 2,030 R. auricularia, 357 R. peregra and 577 S. palustris were collected in seven reservoirs of the River Ruhr catchment area in Germany and a total of 573 R. peregra was collected in five lakes in Iceland. Cercariae were examined and identified live and fixed in molecular grade ethanol for DNA isolation and in hot/cold 4% formaldehyde solution for obtaining measurements from fixed materials. Partial fragments of the mitochondrial gene nicotinamide adenine dinucleotide dehydrogenase subunit 1 (nad1) were amplified for 14 isolates. RESULTS: Detailed examination of cercarial morphology allowed us to differentiate the cercariae of the two Echinostoma spp. of the 'revolutum' species complex. A total of 14 partial nad1 sequences was generated and aligned with selected published sequences for eight species of the 'revolutum' species complex. Both NJ and BI analyses resulted in consensus trees with similar topologies in which the isolates from Europe formed strongly supported reciprocally monophyletic lineages. The analyses also provided evidence that North American isolates identified as E. revolutum represent another cryptic species of the 'revolutum' species complex. CONCLUSION: Our findings highlight the need for further analyses of patterns of interspecific variation based on molecular and morphological evidence to enhance the re-evaluation of the species and advance our understanding of the relationships within the 'revolutum' group of Echinostoma.

• MeSH
• Echinostoma anatomie a histologie   klasifikace   genetika   izolace a purifikace   MeSH
• fylogeneze MeSH
• hlemýždi parazitologie   MeSH
• jezera parazitologie   MeSH
• molekulární sekvence - údaje MeSH
• řeky parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Island MeSH
• Německo MeSH