Clinical implications of bovine spongiform encephalopathy.

Bovine spongiform encephalopathy (BSE) is a new prion disease that was first identified in the United Kingdom in 1987. Its appearance was likely caused by changes in the rendering process used to produce a meat and bone supplement for cattle, changes that allowed this prion to enter the bovine food supply. Despite measures that were made to reduce the risk to humans, a new variant of Creutzfeldt-Jakob disease appeared in the mid-1990s and has been linked to BSE. Although the extent of the disease's impact on humans is not yet known, current estimates predict that there will be 136,000 cases of this fatal disease by the year 2040. The risk to humans of medications produced with bovine materials, gelatin, and blood transfusion is unknown.