title: Molecular diversity of avian schistosomes in Danish freshwater snails.
abstract: Avian schistosomes are widespread parasites of snails and waterfowl and may cause cercarial dermatitis (swimmer's itch) in humans, a disease that is frequently reported in European countries. These parasites are known to occur in Denmark, but here, we applied a new approach using molecular tools to identify the parasites at species level. In order to do that, 499 pulmonate freshwater snails (Radix sp., Lymnaea stagnalis, Stagnicola sp. and Planorbarius corneus) were sampled from 12 lakes, ponds, and marshes in the greater Copenhagen area. Avian schistosome cercariae were identified by microscopy and subjected to molecular investigation by sequencing and phylogenetic analysis of the 5.8S and ITS2 ribosomal DNA for species identification. Additionally, snail hosts belonging to the genus Radix were identified by sequencing and phylogenetic analysis of partial ITS2 ribosomal DNA. Three out of 499 snails shed different species of Trichobilharzia cercariae: Trichobilharzia szidati was isolated from L. stagnalis, Trichobilharzia franki from Radix auricularia and Trichobilharzia regenti from Radix peregra. In the light of the public health risk represented by bird schistosomes, these findings are of concern and, particularly, the presence of the potentially neuro-pathogenic species, T. regenti, in Danish freshwaters calls for attention.
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark. aoechristiansen@gmail.com.
authors.forename: Anne Ø
authors.initials: AØ
authors.lastname: Christiansen
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: Annette
authors.initials: A
authors.lastname: Olsen
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: Kurt
authors.initials: K
authors.lastname: Buchmann
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 7, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: Per W
authors.initials: PW
authors.lastname: Kania
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Nejsum
authors.affiliation: Section for Parasitology and Aquatic Diseases, Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, DK-1870, Frederiksberg C, Copenhagen, Denmark.
authors.forename: Birgitte J
authors.initials: BJ
authors.lastname: Vennervald
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000469:parasitology; D001717:Birds; D058487:Cercaria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D018509:DNA, Helminth / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000737:chemistry; D003718:Denmark / Q000453:epidemiology; D003872:Dermatitis / Q000453:epidemiology / Q000469:parasitology*; D005618:Fresh Water / Q000469:parasitology; D014644:Genetic Variation; D006801:Humans; D008195:Lymnaea / Q000469:parasitology; D010802:Phylogeny; D012551:Schistosomatidae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D012552:Schistosomiasis / Q000453:epidemiology / Q000469:parasitology*; D012876:Skin Diseases, Parasitic / Q000453:epidemiology / Q000469:parasitology*; D012908:Snails / Q000469:parasitology*
chemical_list: D018509:DNA, Helminth; D004275:DNA, Ribosomal
keywords: Avian schistosomes; Cercarial dermatitis; Denmark; ITS rDNA; Parasite-host relationship; Trichobilharzia