[A new variant of Creutzfeldt-Jakob disease. Do we want development of a new epidemic?].

Human spongiform encephalopathies have been receiving a lot of attention lately, because of a new variant of Creutzfeldt-Jakob disease and its possible connection to bovine spongiform encephalopathy which has reached epidemic proportions in Great Britain during the last ten years. Four different human spongiform encephalopathies have been described, the most common being Creutzfeldt-Jakob disease, which can occur in a sporadic, familial or transmissible form. The infectious agent is mainly, possibly solely, composed of a pathogenous isoform of a normal membrane-bound glycoprotein, called a prion. In animals, spongiform encephalopathies occur most frequently in sheep, as scrapie, and in cattle, as bovine spongiform encephalopathy, also known as mad cow disease. There is substantial evidence to suggest that this disease in cattle is the source of the new variant of Creutzfeldt-Jakob disease, although this has yet to be proven. An important question is whether the cases of the new variant of Creutzfeldt-Jakob disease registered so far are the start of an epidemic, as in the case of bovine spongiform encephalopathy.