Five thousand people who have been told they may be infected with the human form of BSE may be asked to agree to post-mortem tests and to donate their bodies in the interests of the living.
Legal and ethical experts will join scientists in an urgent review of how the dead may be screened for evidence of variant CJD, even when it did not kill them. Autopsies on about 30,000 other people who die each year could also routinely include tests to establish whether any were unknowingly carrying the infection. Examination of people who donate their organs for transplant after death is another option to be considered by advisers for the Department of Health.
The review has been ordered amid fears that the incurable disease has a far greater hold on the population than is evident so far, and that it has already been spread between people through contaminated blood transfusions, plasma products or surgical instruments.
The advisers must decide whether the risk to public health is so high that rights to refuse consent for postmortem checks should in some cases be overridden. But there will be concerns that such measures will increase patients' resistance to donating organs or their bodies for research and education.
Variant CJD is impossible to spot in living people until the disease is well advanced. Brains and spleens, lymph tissues, appendixes and tonsils are examined after death to confirm diagnosis.
More than 150 Britons have so far died from the disease in just over 10 years. Safety controls on food should now mean that fewer than 100 more may die from this source, according to statisticians. But scientists expert in vCJD and BSE-like diseases fear a second wave of deaths could be on the way, from people accidentally infected through contaminated surgical instruments or blood transfusion.
Two vCJD deaths have already been linked to blood transfusions while a third patient who died from other causes was found to have evidence of infection in her spleen. She had a different genetic signature from other vCJD patients so far. Such people may take longer to develop an already long-incubating disease or simply be carriers capable of passing on infection to others. Symptoms may also differ so they are missed as vCJD cases. Blood donation controls are now in place, although more cases where infection predated new rules are possible. Advice is also being prepared on cutting the risk of transmission through surgical instruments.
Seac, the committee which advises on vCJD, successfully appealed to the chief medical officer, Sir Liam Donaldson, to conduct a wider legal and ethical review before more testing is authorised. It said: "A substantial number of subclinical carriers of vCJD infection may exist in the UK population who cannot be at present be identified, for example." Seac's chairman, Chris Higgins, of Imperial College London, said: "Even though we have legal and ethical constraints, it may be considered by the Department of Health sufficiently important as a public health risk that some of these have to be overridden."
Sheila Bird, a senior statistician with the Medical Research Council who sits on a Seac sub-group trying to map the disease's progression, said its review of what was known about vCJD in the population "was a pretty salutary appraisal of our ignorance. We need to set in place methods that will allow us to tackle these uncertainties".
Sir Liam, in a letter to Professor Higgins, said: "I agree that there remain significant uncertainties about vCJD, particularly around secondary transmission. You have identified some important gaps in our knowledge and some of the potential challenges for us in addressing these."
