Detection of Chronic Wasting Disease Prions in Soil at an Illegal White-tailed Deer Carcass Disposal Site: An Intersection of the Ecology of Environmental Matrices and Prion Detection Techniques

Abstract

Chronic wasting disease (CWD) is a transmissible neurodegenerative prion disorder affecting cervids such as deer, elk, and moose, causing rapid and severe neurological degeneration followed by eventual death. Once CWD prions have accumulated in the body, they can be shed from infected animals through excreta and secreta such as saliva, blood, urine, and feces. Prions shed into the environment can persist in environmental matrices for a currently undefined amount of time, posing significant environmental contamination concerns. Prion contaminated soils could serve as a reservoir for persistent prion transmission in cervids, and pose unknown risks to wildlife, humans, and ecosystems as a whole. We validated the use of RT-QuIC in vitro prion amplification assay to detect prions in soil at an illegal white-tailed deer (Odocoileus virginianus, WTD) carcass disposal site in Beltrami County, Minnesota. To do this, we prioritized soil sampling around 11 locations from which we had previously detected CWD in biological material from WTD remains using RT-QuIC. Given the history of PrPCWD-positive carcass material decomposition at this site, we aimed to characterize the extent of environmental contamination around these focal points. We detected CWD in 28 soil samples across 17 locations out of 207 soil samples tested. Of these detections, 17 soil samples were located at sites which also demonstrated prion seeding activity in biological samples from WTD remains. These detections suggest that this carcass disposal practice can have widespread and long-term implications for the contamination of environmental matrices including the potential to cause prion contamination hot spots in the environment.