Variant CJD still poses threat to public health, warn expertsBMJ 2013; 347 doi: http://dx.doi.org/10.1136/bmj.f7142 (Published 28 November 2013) Cite this as: BMJ 2013;347:f7142
The risk of variant Creutzfeldt-Jakob disease (vCJD) to public health in the United Kingdom is still very much a reality and requires funding for research and universal blood tests, scientific experts have warned.
MPs on the House of Commons Science and Technology Committee holding an evidence session on 27 November as part of their inquiry into vCJD were told by experts of the ongoing risks of the disease.
The degenerative brain disease, sometimes called the human form of bovine spongiform encephalopathy (BSE) or “mad cow disease,” emerged after widespread exposure to BSE prions in the late 1980s and early 1990s through contaminated meat products in the food chain.
At the evidence session, Andrew Miller, the committee’s chairman and Labour MP for Ellesmere Port and Neston, asked, “Do you think that variant CJD continues to pose a significant risk to public health?”
John Collinge, professor of neurology at University College London Institute of Neurology and director of the Medical Research Council (MRC) Prion Unit, giving evidence, replied, “Absolutely. The study that you will have seen published in the BMJ recently . . . is extremely concerning.”
The BMJ study,1 published in October, estimated that one in 2000 people in the UK carry vCJD proteins although there have been only 177 clinical cases of vCJD to date in the UK.
Uncertainty remains about how many people will eventually develop the disease because the risk of carriers transmitting the disease by blood transfusion or surgery is unknown.
Referring to the BMJ study, Collinge said that there was a significant problem because this disease could have prolonged incubation periods and carriers posed a risk to others because they would have high levels of infectious prions in their tissue so could pass that on if they were blood or organ donors or if they infected surgical equipment.
“The problem I am most concerned about is the fact that regardless of whether these individuals in the incubation period will develop the disease in five, 10 or 50 years, or whether they will be healthy carriers for the rest of their lives and die of something else, they still pose a potential risk to others, particularly by blood transfusion,” he said.
Roland Salmon, joint chairman of the Advisory Committee on Dangerous Pathogens TSE Sub Group—part of the Department of Health—also giving evidence, said, “If you mean are we likely to get a big number of cases, I remain guardedly optimistic that we won’t.
“To prevent this becoming a self-sustaining epidemic has to remain a significant concern for public health authorities. That view is widely held across the profession.”
MPs asked if the government response to this need for vigilance was adequate.
Fellow witness James Ironside, professor of clinical neuropathology at the National CJD Research and Surveillance Unit, University of Edinburgh, said, “I think the government has done a lot to try and deal with the threat posed by variant CJD transmission.
“There have been a large number of steps put in place to try to reduce the risks of transmission of variant CJD through blood. There have also been other steps to reduce the risks through surgical instruments. I think the measures in place are sufficient.”
MPs asked if the UK’s blood transfusion supply was free of variant CJD prions, to which Ironside replied, “I don’t think we can give that guarantee. The blood supply could contain vCJD infection. The steps should result in substantial reduction in that risk, although not a complete elimination.”
Collinge said that he was unhappy that the NHS has not yet universally taken on board a blood test that had been designed to identify vCJD.
“My unit reported the first such blood test in the Lancet two years ago,” he said. “This test is now in clinical use at the national prion clinic. We use it for diagnosing variant CJD. This is a prototype test that could be developed into one that the national blood service could routinely use. At the moment our attempts to persuade commercial companies to take that on have come to nothing.”
Another study of the test was needed, he argued, but currently any such study did not have the £750 000 (€899 000; $1.2m) funding that was needed.
Cite this as: BMJ 2013;347:f7142
bmj.com Editorial: How widespread is variant Creutzfeldt-Jakob disease? (BMJ 2013;347:f5994, doi:10.1136/bmj.f5994); Research: Prevalent abnormal prion protein in human appendixes after bovine spongiform encephalopathy epizootic (BMJ 2013;347:f5675, doi:10.1136/bmj.f5675); Research: Prevalence of disease related prion protein in anonymous tonsil specimens in Britain (BMJ 2009;338:b1442, doi:10.1136/bmj.b1442)