Variant Creutzfeldt-Jakob disease and blood transfusion.

Variant Creutzfeldt-Jakob disease (vCJD) was first described in the United Kingdom in 1996 and is thought to have been transmitted from cattle infected with bovine spongiform encephalopathy probably via the food chain. Thus far just over 100 definite or probable clinical cases have been described, though the number of people currently infected and the eventual size and geographic distribution of any future clinical epidemic remain uncertain. There is little evidence that sporadic CJD is transmitted by blood transfusion. However, the same cannot necessarily be assumed to apply to the new variant strain of disease in which involvement of peripheral lymphoid tissues has been demonstrated. In the face of uncertainty surrounding the risk of transmission of vCJD by blood products, blood transfusion services in a number of countries have implemented precautionary policies, though whether in the long term these will prove to have been necessary or sufficient remains to be seen.