Bovine spongiform encephalopathy: the causal role of ruminant-derived protein in cattle diets.

Although bovine spongiform encephalopathy (BSE) has occurred in other European countries, the major epidemic has been in the United Kingdom (UK), where there have been more than 163,000 cases so far. BSE has been linked to the practice of feeding meat-and-bone meal (MBM), putatively contaminated with scrapie agent, to cattle. A ban on the feeding of MBM to ruminants in the UK has resulted in a significant decline in the number of reported cases. It is considered that BSE in other European countries probably originated through the use of British MBM in the diets of cattle in these affected countries. Recently, in the UK, a new variant form of Creutzfeldt-Jakob disease in humans has been discovered, which does not appear to have occurred before the advent of BSE. It may have been caused by BSE agent, possibly as a consequence of dietary exposure. The use of MBM in the diets of any livestock species has now been prohibited in the UK.