Scrapie is an invariably fatal, infectious disease of adult sheep and goats characterised by degeneration of the central nervous system. It is one of the Transmissible Spongiform Encephalopathies (TSE), a disease family which includes Bovine Spongiform Encephalopathy (BSE) in cattle, Chronic Wasting Disease (CWD) in deer, and Kuru and variant Creutzfeldt-Jakob Disease (vCJD) in humans. Scrapie was first discovered in European sheep in the early 18th Century and is now present in many sheep populations worldwide.