§ Mr. BurstowTo ask the Secretary of State for Health what assessment his Department has made of the link between vCJD, BSE and rogue prions. [86763]
§ Ms Blears[holding answer 19 December 2002]: Creutzfeldt Jakob disease (CJD) in humans and bovine spongiform encephalopathy (BSE) in animals are part of a group of diseases called transmissible spongiform encephalopathies (TSEs) or prion diseases. The precise nature of the agent responsible for CJD is not fully understood, but the most likely theory points to an abnormal form, known as a prion, of a normal cell protein. According to the protein-only hypothesis, infectious prions are composed mainly if not entirely of the abnormal form of the prion protein, which aggregates in infected tissue.
Post mortem examination of the brains of CJD patients and BSE animals shows the accumulation of the abnormal protein and there is a massive destruction of the brain, which shows the characteristic spongy appearance.
Although there is no direct evidence that the BSE prion is infectious to humans, obtaining such evidence could not be justified ethically as this would require humans to be inoculated with BSE agent. A judgment on the link between BSE and vCJD inevitably depends on an assessment of a range of clinical, pathological, epidemiological and laboratory based evidence. There is now convincing evidence that the agent causing BSE is 185W the cause of vCJD, although there remains uncertainty about the future number of cases and the mechanism of transmission of BSE to humans.