Occurrence of Trichinella spp. infestations in black bears in Quebec, Canada

Trichinella spp. are parasitic nematodes with a worldwide distribution that infect mammals, birds, and reptiles. Trichinella is composed of at least 13 taxa; the latest taxon, T13, was identified in wolverines in northwestern Canada in 2020. Trichinella is of public health importance because trichinellosis (trichinosis) is a zoonosis transmitted by eating undercooked meat from wild or domestic animals. In Canada, wild game species are the main source of infection; outbreaks in people originate almost exclusively from consumption of bear and walrus meat. Black bears (Ursus americanus), with a population of ~70,000 individuals, are widespread in Quebec; they are a commonly hunted species and a potential source of infection. To estimate the incidence of this parasite in the black bear population, we collected 250 tongue samples from 14 different Quebec regions. A single sample from a female black bear from the Côte-Nord region was positive, resulting in an estimated prevalence of 0.4% (95% CI [0.01, 2.21]). The larval content of >5 larvae/g in this sample was 5 times the minimal infectious dose for humans. Hence, although the prevalence of Trichinella spp. in our survey of black bears in Quebec was relatively low, clinical manifestation in humans is likely to occur when eating meat from such an infected animal, underscoring the need to follow the recommended cooking practices before consuming bear meat.