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Önnur málmyndSwimmer's itch in Landmannalaugar, Iceland
CitationLæknablaðið 2005, 91(10):729-36
ÚtdrátturSwimmer's itch (SI) or human cercarial dermatitis is caused by free-swimming larvae of bird parasites of the family Schistosomatidae (Trematoda) which have penetrated thorough the skin. Sometimes, mainly during first infections, the larvae do not cause any symptoms but if trapped by the immune system of the host each larva causes a maculopapular eruption. So far, five bird schistosome species have been reported in Iceland. Cercariae are shed by the freshwater snail Radix peregra but adults live in anseriform birds; one nasal Trichobilharzia species occurs in the nasal cavity of mallards, two visceral species have been found in veins of whooper swans and a visceral species has been found in greylag goose and in mallards, respectively. Experiments have shown that developing schistosomulae are able to survive for days or even weeks in mammals. Long term pathologic effects on the host are unknown. During the second half of August 2003 thousands of bathers got SI in a slowly streaming brook with geothermally heated groundwater in Landmannalaugar, the most frequently visited area in the interior of Iceland. The number of cercariae in the water and SI cases decreased until October but still in December and in late winter 2004 SI cases were reported. In August 2004 SI again started in the area but the density of cercariae in the water seemed to be less than in the previous year. The prevalence of snails shedding Trichobilharzia cercariae on the bathing site never exceeded 1%. The rapid increase of cercariae in the water by the middle of August in 2003 and 2004 were caused by a breeding mallard female and its ducklings which were raised on the bathing site during summer. All the ducklings had nasal- and visceral Trichobilharzia infections which they must have acquired soon after hatching. Three weeks later the adult worms could have started egg-laying. Consequently, emerging miracidia infected the snails which finally started shedding the cercariae by middle of August in 2003 and 2004. In future years this rapid increase of cercariae could be avoided if ducklings are not allowed to have access to the bathing site and the adjacent brook. Retrospective enquiries suggest that some visitors have occasionally got SI after bathing in the brook in preceding decades. Low number of papules, however, indicates a low density of cercariae in the water.
Lu00FDsingHægt er að lesa greinina í heild sinni með því að smella á hlekkinn View/Open
- A review on swimmer's itch and the occurrence of bird schistosomes in Iceland.
- Authors: Skírnisson K, Aldhoun JA, Kolárová L
- Issue date: 2009 Jun
- [Visceral lesions in mammals and birds exposed to agents of human cercarial dermatitis].
- Authors: Bayssade-Dufour Ch, Vuong PN, René M, Martin-Loehr C, Martins C
- Issue date: 2002 Nov
- Prevalence and transmission of cercariae causing schistosome dermatitis in Flathead Lake, Montana.
- Authors: Loken BR, Spencer CN, Granath WO Jr
- Issue date: 1995 Aug
- [The effect of praziquantel on Trichobilharzia (Digenea, Schistosomatidae), a cause of swimmer's dermatitis in humans].
- Authors: Müller V, Kimmig P, Frank W
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- [Are nasal Trichobilharzia cercariae potential threath to human health?].
- Authors: Skírnisson K, Kolarova L
- Issue date: 2002 Oct