Variant Creutzfeldt-Jakob disease and the Quebec blood supply.

© 2000 Canadian Medical Association or its licensors In the mid-1980s bovine spongiform encephalopathy (BSE) was recognized as an emerging prion disease of epidemic proportions in the United Kingdom. In April 1996, researchers in the UK announced that they had identified 11 patients with a new form of spongiform encephalopathy, now called variant Creutzfeldt–Jakob disease (vCJD). Since then, more than 70 definite or probable cases of vCJD have been identified, all of them in the UK, except 1 in Ireland and 3 in France (1 of which has not been officially confirmed). Although definite proof is still lacking, current evidence indicates that these human cases were infected with the same strain of prion that causes BSE. In all likelihood the infections resulted from the ingestion of BSE-contaminated food. Because of the very long incubation period of transmissible spongiform encephalopathies, the true epidemic potential of vCJD in humans exposed to BSE is still unknown. Furthermore, the potential for transmission of vCJD through transfusion has not been defined, simply because the relevant laboratory and epidemiologic data are not yet available for this emerging disease. However, all the available data strongly suggest that classic CJD is not transmissible by transfusion. In the midst of such uncertainty, the Bayer Advisory Council on Bioethics made the specific recommendation, in October 1998, that “persons who [...] have resided in a geographic area with a significant incidence of BSE or [vCJD] [should] not be permitted to contribute blood or plasma until the hypothetical risk of accepting donation from such persons can be evaluated.” This recommendation did not take into account the potential impact of such a measure on the availability of donors, and the resulting effect on the blood supply. To address this issue, Héma-Québec conducted a survey in collaboration with the Canadian Blood Services and Health Canada to determine the proportion of donors who had travelled to countries affected by BSE (Table 1).