Variant CJD in humans has been linked to eating cattle products contaminated with the bovine spongiform encephalopathy (BSE) agent. Specified risk materials (SRM), or parts that have been identified as having the potential to carry the BSE agent in infected animals, are banned from human food and include brain, spinal cord, eyes, dorsal root ganglia, trigeminal ganglia and vertebral column for cattle older than 30 months of age and tonsil and distal ileum (lower part of the small intestine) of all cattle. For more information on the causes and transmission of BSE, please visit the BSE section of the resource.
Despite widespread human exposure to the BSE agent in the U.K. during the BSE epidemic that peaked in the early 1990s, the annual number of symptomatic vCJD cases in the U.K. was never as high as that of sporadic CJD cases.
Four cases of vCJD infection acquired via blood transfusion have been reported in the U.K. In all of these cases, the blood was donated by persons before their onset of vCJD.9 The U.S. Food and Drug Administration (FDA) has a blood donor deferral policy designed to reduce the risk of transfusion transmission of vCJD.