New-variant Creutzfeldt-Jakob disease: the risk of transmission by blood transfusion

New-variant Creutzfeldt-Jakob disease (nvCJD) was first described in the UK in 1996 and is thought to be related to the consumption of cattle sufferin g from bovine spongiform encephalopathy. Although only 29 cases have been c onfirmed to date, it is too early to predict the number of people who may c urrently be incubating the disease. Past experience suggests that sporadic CJD is rarely, if ever, spread by blood transfusion. However, it is unclear whether nvCJD may be transmissible by this route and if so, how easily. As sessing the potential risk of transmission of nvCJD by blood transfusion an d evaluating the likely efficacy of proposed strategies to reduce this risk is, therefore, very difficult. This article summarizes the spectrum of tra nsmissible spongiform encephalopathies in animals and man, the molecular an d cellular biology of the prion protein and the continuing debate as to the nature of the infectious agent. The distribution of normal prion protein e xpression, the results of experimental transmission studies and the case re ports and clinical studies on CJD transmission are reviewed. Finally, the e xtent of current knowledge and the potential utility of proposed strategies to reduce the risk of nvCJD transmission by blood transfusion are discusse d.