Soil-mediated prion transmission: is local soil-type a key determinant of prion disease incidence?

Prion diseases, including chronic wasting disease (CWD) and scrapie, can be transmitted via indirect environmental routes. Animals habitually ingest soil, and results from laboratory experiments demonstrate prions can bind to a wide range of soils and soil minerals, retain the ability to replicate, and remain infectious, indicating soil could serve as a reservoir for natural prion transmission and a potential prion exposure route for humans. Preliminary epidemiological modeling suggests soil texture may influence the incidence of prion disease. These results are supported by experimental work demonstrating variance in prion interactions with soil, including variance in prion soil adsorption and soil-bound prion replication with respect to soil type. Thus, local soil type may be a key determinant of prion incidence. Further experimental and epidemiological work is required to fully elucidate the dynamics of soil-mediated prion transmission, an effort that should lead to effective disease management and mitigation strategies.