Since it was identified in the mid-1980s in Britain, mad cow disease, or Bovine Spongiform Encephalopathy (BSE), has resulted in the slaughter of millions of cattle – and the deaths of dozens of people from the related brain-wasting disease known as variant Creutzfeldt-Jakob Disease (vCJD). Mad cow scares have since spread across Europe as governments try to cope with possible infections and resultant fears.

The first case of BSE in the United States was confirmed on December 25, 2003.