Mad cow disease is a brain disease in cattle that causes odd behavior, difficulty walking, and then death. It is also called bovine spongiform encephalopathy << BOH vyn SPUHN jih fawrm ehn sehf uh LOP uh thee >> . Mad cow disease and other prion diseases produce damaged brain tissue that looks spongelike under a microscope.
Mad cow disease was first identified in 1986 in the United Kingdom, where sheep suffer from a similar disease called scrapie. Scientists think mad cow disease arose when cattle were fed supplements containing brains and spinal cords from scrapie-infected sheep. In 1988, the British government banned the use of cattle and sheep by-products to feed other cattle and sheep. Mad cow disease has been reported in cattle in most countries in Europe, where routine testing for prions has been applied to all slaughtered cattle over 30 months of age. In addition, prion-infected cattle have been found in Canada, Israel, Japan, and the United States.
In 1996, British experts announced that beef from “mad cows” might be linked to a new form of Creutzfeldt-Jakob disease (CJD), a rare prion disease in human beings. Scientists believe that this variant of CJD, called vCJD, was transmitted to people through prion-infected beef. Since 1996, hundreds of thousands of cattle have been destroyed in the United Kingdom in an attempt to prevent further contamination of the food supply. Most countries banned imports of beef from the United Kingdom after 1996. By the mid-2010’s, more than 200 cases of vCJD had been identified, mainly in the United Kingdom and France.
