Parasite populations of river otter and mink in Western Canada, and the first report of the zoonotic trematode Alaria mustelae in river otter in North America

Introduction At the top of aquatic ecosystems, the North American river otter ( Lontra canadensis ) and mink ( Neogale vison ) are definitive hosts to a range of parasite species. Despite their ecological importance in riparian habitats, particularly as indicators of ecosystem health, data on their parasite communities remain limited, especially in Western Canada. Methods We conducted a systemic literature review of the helminth parasites of river otter and mink across North America, highlighting regional patterns in biodiversity. We also surveyed the helminth communities of river otter and mink in Alberta and British Columbia, comparing our data against historical reports. Results In Alberta and British Columbia, parasite diversity was comparatively low relative to other parts of North America, especially when contrasted with the higher diversity observed in the southern United States. Parasite communities in sampled animals were characterized by four main species ( Alaria mustelae, Filaroides martis, Isthmiophora inermis , and Versteria rafei ). Larval infections by mesocercariae of A. mustelae were highly prevalent, and larval migrans was associated with inflammation and fibrosis in various tissues. Increasing intensities of infection were significantly related to decreasing nutritional condition. Discussion As mesocarnivores that connect aquatic and terrestrial food webs, otter and mink are definitive as well as potential intermediate or paratenic hosts for parasitic species that use aquatic hosts. We observed adult and larval infections of V. rafei and A. mustelae in our animals, which are both of concern for zoonotic transmission. As these associations have not been previously reported in otter or mink, it may represent an emergent disease of concern for these important sentinel species. This research highlights a serious gap in knowledge of helminth communities in Western Canada and the threat of zoonotic infection for vulnerable communities. Research to assess the risk of exposure and infection for First Nation communities and fur trappers who handle these mammals is warranted. Furthermore, research into the distribution of these parasites in other intermediate and definitive hosts is required to understand the range of this threat to wildlife and human communities.