usually affects people between 50 and 70 years of age, and it differs clinically and pathologically from variant-CJD, which occurs in younger people. CJD can be transmitted through medical procedures involving tissues from persons with CJD. There is good evidence that the BSE prion causes the human vCJD. Prions of BSE and vCJD are very similar, if not identical, but both differ from the prion of classical CJD. The BSE prion does not cause classical CJD.

To date, BSE has been identified only in beef and in other food containing ingredients made from cattle. There is no reason to believe that other European foods are affected.