How much is known about bovine spongiform encephalopathyBovine spongiform encephalopathy (BSE), also known as 'mad cow disease', is a neurodegenerative disease of cattle caused by prions (12), first described in the United Kingdom (UK) in 1986 (17). Bovine spongiform encephalopathy has been shown to belong to the group of disorders known as the transmissible spongiform encephalopathies (TSEs). Transmissible spongiform encephalopathies affect both animal species and humans, and include, among others, scrapie of sheep and goats, chronic wasting disease of deer, transmissible mink encephalopathy, feline spongiform encephalopathy (FSE), and Creutzfeldt-Jakob disease (CJD), fatal familial insomnia and Kuru of humans.At present, feeding cattle with contaminated meat-and-bone meal (MBM) constitutes the main route of infection (18). Vertical or other means of transmission, should they occur, would be at an extremely low incidence.