Variant Creutzfeldt-Jakob disease.

SUMMARY: Variant Creutzfeldt-Jakob disease (CJD) is an emerging form of human prion disease caused by oral exposure to the bovine spongiform encephalopathy agent. Most cases have occurred in the UK, but smaller numbers of cases have been identified in 10 other countries worldwide. All confirmed cases belong to a single genetic subgroup defined by methionine homozygosity at codon 129 in the prion protein gene. Variant CJD has a widespread distribution of infectivity in the body, involving lymphoid tissues during at least the latter part of the incubation period. This is unlike other forms of human prion disease, and raised concerns that the transmissible agent might also be present in blood. To date, four probable cases of variant CJD infection have been identified following transfusion of packed red blood cells from asymptomatic donors who subsequently died from variant CJD. Recently, one case of likely transmission of variant CJD infection by UK factor VIII (FVIII) concentrates has been reported in an elderly haemophilic patient in the UK, who had been treated with FVIII produced from pooled plasma to which a donor who subsequently died from variant CJD had contributed. The recipient showed no signs or symptoms of variant CJD during life, but evidence of variant CJD infection was detected in his spleen following a postmortem examination. Continued surveillance is required to investigate the prevalence of secondary variant CJD infection in other patients with bleeding disorders who have been treated with UK-sourced pooled plasma products.