Can Potamopyrgus antipodarum (Gastropoda) affect the prevalence of Trichobilharzia szidati in Lymnaea stagnalis populations?

Swimmer's itch is an emerging disease caused by bird schistosomes affecting people all over the world. Lymnaeidae − main host snails in Europe − are the source of harmful cercariae of these zoonotic parasites. The aim of this work was to determine whether Polish lakes, inhabited by Potamopyrgus antipodarum (Gray, 1843), result in a lower potential risk of swimmer's itch compared to lakes uninhabited by this non-native snail species. As a result of the dilution effect created by increasing the diversity of co-occurring non-host targets for miracidia, the risk of this zoonosis may be reduced. We studied the prevalence of digenean trematodes in Lymnaea stagnalis (Linnaeus, 1758) populations from 30 water bodies partly inhabited by P. antipodarum. The bird schistosome infection in snail hosts was found in five lakes inhabited and 11 lakes uninhabited by the non-native snails. The prevalence of these parasitesin host snail populations in the lakes uninhabited was significantly higher than in lakes inhabited by P. antipodarum. We conclude that P. antipodarum seems to be a good potential target for reducing the risk of swimmer's itch via the dilution effect. We expect from our point of view to stimulate a discussion on the use of this species to protect bathing areas against the threat of swimmer's itch.