Trematode Infection Prevalence Increases With Snail Richness: Observations From a 4-Year Study of Snail-Trematode Interactions.

Digenetic trematodes are valuable study organisms for exploring how biodiversity influences disease. In this study, we investigated the relationship between snail richness and trematode infection prevalence using data from a 4-year study (2019-2022) of eight wetland sites in Alberta, Canada. Trematode species were classified as specialists or generalists at the first-intermediate host level, and generalized linear mixed-effects models were employed to assess the relationship between snail richness and overall, generalist, and specialist infection prevalence. The findings indicate that as snail richness increased, there was a significant increase in the overall and generalist infection prevalence. This trend was also noted for specialist infections but was not significant. A notable decline in infection prevalence was observed for all three categories in the final sampling year compared with the first year. Additionally, we found no relationship between snail richness and trematode richness. Trematode and snail-trematode interaction sample completeness and rarefaction analyses indicated that high sample coverage was obtained, but further trematode species remain to be cataloged. We also uncovered interesting one-off infections that could have important implications for disease monitoring and management strategies that rely on snail hosts, emphasizing the need for continued surveillance of host-parasite relationships.