bovine spongiform encephalopathy

Disease of cattle, related to scrapie in sheep, that attacks the nervous system, causing aggression, lack of coordination, and collapse. It was formally identified in the UK in November 1986, and between 1986 and 2002 there were 181,376 cases of BSE identified in British cattle, which were all slaughtered to contain the spread of the disease. After safety measures were put in place for the selection and processing of cattle, British beef was declared safe (by the UK government) in 1999. Following outbreaks of BSE in French, German, and Spanish cattle in late 2000, European Union (EU) agriculture ministers agreed to ban, as of 1 January 2001, the use of meat-and-bone meal from animal feed and to ban all cattle over 30 months old from the food chain unless tested for BSE.

BSE is one of a group of diseases known as the transmissible spongiform encephalopathies (TSEs), since they are characterized by the appearance of spongy changes in brain tissue. The diseases are closely related, and the ‘new variant’ Creutzfeldt–Jakob disease (CJD) in humans was shown to be caused by the BSE pathogen, as in 1996 a link was established between the deaths of 10 young people from CJD and the consumption of beef products.

BSE, like all TSEs, is caused by a new type of pathogen known as a prion. After a long-running controversy, it has been established that prions consist exclusively of protein. Typically they are abnormal variants of the host's own proteins, adopting structures that are prone to aggregation.