The transmission of prions to humans.

The identification of new-variant Creutzfeldt-Jakob disease (nvCJD) in 1996 led to the proposal that this new disease was caused by the transmission of bovine spongiform encephalopathy (BSE) to the human population. The ramifications of such a proposal have been extensive and profound, both politically and on the general public in the UK and other countries. Patients with nvCJD exhibit a consistent set of clinicopathological features, and cases of nvCJD continue to be reported almost exclusively in the UK, the country with by far the highest incidence of BSE. Laboratory studies, including transmission experiments in mice, provide strong support for the hypothesis that nvCJD is caused by BSE.