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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 at 43 localities. (a) Sequence analysis of ITS-2 rDNA disclosed that the collected snails belong to four species - R. auricularia (Linnaeus, 1758), R. peregra (Müller, 1774), R. lagotis (Schrank, 1803) and R. labiata (Rossmaessler, 1835) (criteria and names are based on the work of Bargues et al. 2001). Occurrence of R. peregra in the Czech Republic was confirmed by molecular data for the first time. (b) Characterization of reproductive system disclosed differences in location, size and shape of bursa copulatrix and its ductus. Unfortunately, some R. labiata specimens shared morphological features of reproductive organs with R. lagotis. (c) Statistical analysis of shell morphology proved that significant differences exist among particular species. One prediction model showed that correct classification of species may be achieved in 82-84% of cases. However, identification of individual snails in the field (without knowledge of respective snail population and use of statistical tools) still remains a complicated issue due to overlaps of shell characteristics. Concerning the role in trematode transmission, R. lagotis, R. labiata and R. peregra are susceptible to Trichobilharzia regenti. Also, successful experimental infections of R. lagotis and R. labiata by Fascioloides magna were accomplished. [ABSTRACT FROM AUTHOR]

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 fluke is monitored in many European countries, including the Czech Republic (with some foci of prevalence over 90%). During the years 2009 and 2010, 1622 survey forms focused on monitoring of fascioloidosis were distributed in the community of "Czech Inspectors of Hunted Game" (CIHG), and 21.3% of forms containing positive or negative response about F. magna occurrence were returned. The administrative units monitored by particular CIHG, who answered the forms, were geographically equally distributed and therefore we believe that also the recorded distribution of F. magna in wild-life animals reflects the real situation in the Czech Republic. A significant number of cases of F. magna infection were repeatedly reported from areas in the south-west part of the Czech Republic. Moreover, our report contains also some unique records of several new F. magna foci in the western (close to the German border), northern (close to the Polish border) and central parts of the Czech Republic, supporting the assumption that the parasite is spreading further throughout Europe. In five game administrative units F. magna infection was directly confirmed by examination of dissected deer livers or by microscopic examination of coprological samples, followed by isolation of DNA from adults and eggs and further molecular analyses. Fascioloides magna intermediate host snails (Galba truncatula and Radix spp.) were collected during 2009 and 2010 from different localities of the Czech Republic, kept in aquaria, examined for shedding of F. magna cercariae, dissected and parasite/snail DNA was isolated. After PCR with specific primers for parasite/snail internal transcribed region number two (ITS-2) the obtained sequences confirmed identification of the following species: F. magna, G. truncatula, R. peregra, R. lagotis, R. labiata and R. auricularia. Although it has been demonstrated that the number of areas with positive cases of fascioloidosis is still growing, the risk of pathogenic impact of F. magna on populations of free-living animals and farming cervids/bovids is generally underestimated. [ABSTRACT FROM AUTHOR]