To host or not to host: participation of the exotic snail Viviparus georgianus in the swimmer’s itch parasite life cycle

Swimmer's itch is a disease that can cause severe rashes on human skin, and is common in many recreational lakes in North America.The parasite responsible for this disease is an aquatic digenean trematode larva (cercaria) of the genus Trichobilharzia which has a complex life cycle.It needs two hosts to complete its cycle: a waterfowl as a definitive host and a snail (normally from Lymnaeidae, Physidae or Planorbidae families) as an intermediate host.So far, no study has mentioned the exotic banded mystery snail, Viviparus georgianus (syn: Callinina georgiana), as a host of this parasite.The aim of this project was to determine whether V. georgianus can be an intermediate host of the parasite responsible for swimmer's itch.To verify this, we compared the infection prevalence rates of native and exotic snails in Lake Memphremagog (Quebec, Canada).After a 17 hour-exposure to artificial light at room temperature, snails were tested for cercarial infection.None of the V. georgianus released cercariae.Based on these results, we have not found any evidence to suggest that V. georgianus is an intermediate host of the parasite species.However, two indigenous snails Ladislavella sp.(Family: Lymnaeidae) and Helisoma anceps (Family: Planorbidae) were confirmed to release cercariae.The prevalence of the infection in native snails was 5% and the estimated average cercariae was between 60 to 1900 per 100 ml.Here, we present evidence that the exotic banded mystery snail does not contribute to the life cycle of the swimmer's itch parasite in Quebec.