[Bovine spongiform encephalopathy and natural scrapie].

Scrapie in sheep and Bovine Spongiform Encephalopathy in cattle are neurodegenerative diseases. They belong to the group of transmissible spongiform encephalopathies (prion diseases). Scrapie is a worldwide enzootic disease, first described two centuries ago. It is due to more than 20 different strains of agent and strongly influenced by genetic factors of the host. There is no evidence of a link between this disease and human transmissible spongiform encephalopathies. Bovine Spongiform Encephalopathy is a consequence of oral infection of cattle by meat and bone meal produced in the United Kingdom and contaminated by the agent. The strain is unique and has been selected and massively amplified in the alimentary chain. It is probably linked to a new variant of Creutzfeldt-Jakob disease in man. It is expected that the ban on the incorporation of animal proteins in the alimentation of ruminants will soon eradicate it, although the risk of potential mutants of the disease and its possible transmission to sheep and goats exists.