Abstract
The present occurrence of bovine spongiform encephalopathy (BSE) in Great Britain is likely to be due to a change in the technology of manufacturing feed mixtures for cattle which was introduced at the beginning of the eighties when the use of organic solvents and high temperatures was restricted during the processing of meat and bone meal of ruminants, mainly of sheep, that are used to prepare these feed concentrates. As the scrapie of sheep has been an endemic disease in Great Britain for more than 200 years, BSE origin is explained by an ''interspecific leap'' of the scrapie agent as a result of these technological changes.
Since 1986, when the first case of this new transmissible spongiform encephalopathy was diagnosed, 160 000 head of cattle with suspect or proved BSE have been sacrificed. The paper contains a chronological description of all important measures taken by the British Government and EU Commission to diminish the risks of potential transmission to humans and to eradicate BSE occurrence in Great Britain.