BACKGROUNDConcerns have been raised that variant Creutzfeldt-Jakob disease (vCJD) might be transmissible by blood transfusion. Two cases of prion infection in a group of known recipients of transfusion from donors who subsequently developed vCJD were identified post-mortem and reported in 2004. Another patient from this at-risk group developed neurological signs and was referred to the National Prion Clinic.METHODSThe patient was admitted for investigation and details of blood transfusion history were obtained from the National Blood Service and Health Protection Agency; after diagnosis of vCJD, the patient was enrolled into the MRC PRION-1 trial. When the patient died, brain and tonsil tissue were obtained at autopsy and assessed for the presence of disease-related PrP by immunoblotting and immunohistochemistry.FINDINGSA clinical diagnosis of probable vCJD was made; tonsil biopsy was not done. The patient received experimental therapy with quinacrine, but deteriorated and died after a clinical course typical of vCJD. Autopsy confirmed the diagnosis and showed prion infection of the tonsils.INTERPRETATIONThis case of transfusion-associated vCJD infection, identified ante-mortem, is the third instance from a group of 23 known recipients who survived at least 5 years after receiving a transfusion from donors who subsequently developed vCJD. The risk to the remaining recipients of such transfusions is probably high, and these patients should be offered specialist follow-up and investigation. Tonsil biopsy will allow early and pre-symptomatic diagnosis in other iatrogenically exposed individuals at high risk, as in those with primary infection with bovine spongiform encephalopathy prions.