Scrapie is a fatal prion disease that affects the central nervous system of sheep and goats. It derived its name from one of its clinical manifestations. An infected sheep or goat compulsively scrapes off its fleece against fences, trees, or other rough objects. Transmission is thought to spread most commonly from a mother sheep or goat to her offspring through infectious placenta or amniotic fluid. Soil also represents a plausible reservoir for the disease. Prions (PrPSc) are shed from sheep and goats in feces and other excrement, such as urine. Prions are known to persist in the environment for years without losing their pathogenicity. Since sheep and goats ingest soil, it has been argued that this could very likely be another avenue for infection.