COYOTES (CANIS LATRANS) MITIGATE ENVIRONMENTAL ACCUMULATION OF CHRONIC WASTING DISEASE PRIONS

Understanding natural processes that influence the spread of pathogens is of great societal and ecological value. Scavengers can play critical ecological roles in epidemiological processes and are assumed to influence environmental transmission of chronic wasting disease (CWD), a fatal prion disease of cervids with extended environmental persistence. As a primary scavenger of cervid carrion in North America, evaluating the role of coyotes (Canis latrans) in CWD environmental transmission is of interest and has management implications. To assess the role of coyotes in CWD transmission, we fed eight adult coyotes three concentrations of CWD-positive brain homogenate: low (5.00×104 SD50 units total), moderate (5.00×106 SD50 units total), and high (5.00×108 SD50 units total) to approximate CWD exposure levels of coyotes in the wild from consumption of different tissues in end-stage infected cervids. We used real-time quaking-induced conversion to determine the relative amount of prions in coyote feces post-passage, as well as to test coyote tissues for prions post-mortem. Across all dosages, coyotes excreted an estimated mean of <1% of ingested prions (interquartile range: 0.02–12.58%). Animals fed higher doses of prions excreted greater amounts of prions; however, amounts remained low (moderate-dose excretion: estimated mean of 15.73%; high-dose excretion: estimated mean of 6.03%), and carnivore fecal matter is not typically consumed by cervids. Furthermore, necropsies revealed no prion seeding activities in the tissues of study animals 1 wk after ingesting their last dose, despite repeated exposure. These results demonstrate that coyotes can remove CWD prions from ingesta and, thereby, provide an important ecosystem service by mitigating the environmental accumulation of one of the most environmentally robust pathogens known.