Warning over second wave of CJD cases

Scientists say that threat of brain illness returning will persist for decades


The Observer, Sunday 3 August 2008

Doctors and scientists have warned that a second wave of CJD cases could sweep Britain over the next two to three decades. The initial outbreak of the fatal brain illness peaked several years ago but could break out again, they argue.

The prediction comes as officials consider ending some of the research projects that were set up to improve understanding of CJD - Creutzfeldt-Jakob disease - and the closely related illness in cows, BSE.

The Department for Environment, Food and Rural Affairs confirmed last week that some experiments aimed at providing detailed data on ways in which cattle could be struck by infectious particles, or prions, would soon be wound up. 'Where cattle are approaching 10 years old, we will probably need to end the experiments in the next year or so,' said a spokesman.

It is estimated that cases of BSE - bovine spongiform encephalopathy - have cost the European Union €80bn (£65bn). However, the condition has since been eliminated in UK cattle and numbers of human cases have declined dramatically. Health officials are now examining expenditure on the screening of blood, beef and surgical instruments.

Neurobiologist Professor Colin Blakemore of Oxford University, former head of the Medical Research Council (MRC), said: 'We have to ask just how much effort and money we should be putting into dealing with BSE and its human counterpart, variant CJD. Either the epidemic is all over and we have nothing to worry about, or we may be facing a second wave among humans. We are going to have to work out the risks very carefully.'

BSE first appeared in cattle in Britain in 1986 and was found to infect humans - in the form of variant CJD - 10 years later. Nineteen-year-old Stephen Churchill, of Devizes, Wiltshire, was identified as its first victim, triggering widespread alarm. It was claimed that tens of thousands of people could be killed. In fact, vCJD has killed only 164 people over the past 13 years in Britain, with the number of cases peaking at 28 in 2000. Only one new case has been recorded so far this year.

But scientists warn that the worst may not yet be over. 'We must not forget that almost every person in the UK was exposed to the agent that causes variant CJD,' said Professor John Collinge, head of the MRC's prion unit in London. 'It went through the entire food chain, not just in burgers but in cakes containing gelatins made from meat products. Even cosmetics contained beef-derived chemicals then.'

In fact, the extent to which people were brought into contact with a deadly human pathogen was unprecedented. Hence the insistence that while some relaxation of BSE monitoring was now acceptable, there should be no reduction in efforts to understand CJD. Certainly it is far too early to assume that Britain - the country most affected by BSE and vCJD - is in the clear, say researchers. They believe a second wave of cases will probably occur, based on studies of a closely related disease, kuru, which affected tribes in New Guinea.

Researchers have found that a key gene shapes the body's defences against kuru and this exists in two forms: version-m and version-v. These gene versions produce different responses to kuru. Individuals who have two m-versions (one from each parent) are the first to succumb to kuru, while those with one or two v-genes have a delayed onset.

Crucially, scientists have now found a similar picture among vCJD patients. Every victim to date has possessed two m-versions, a point stressed by Professor Chris Higgins, chair of the government's Spongiform Encephalopathy Advisory Committee (SEAC).

'About 40 per cent of the population is double-m,' he said. 'We have seen 160 cases develop. That suggests the remaining 60 per cent of the population will throw up about 250 cases some time in the next couple of decades. In other words, we face at least one more wave of variant CJD in Britain. That suggests we need to maintain our research efforts into finding treatments for the condition.'

'So far, UK funding has remained strong in its support for CJD work, though researchers in France and Germany have already noted grants for CJD work are drying up,' Collinge told The Observer. 'That would be a mistake if it were repeated here. We have the chance not just to find treatments for future CJD cases but to make progress in understanding conditions such as Alzheimer's and Parkinson's, which - although not caused by the same agent that triggers CJD - progress in very similar ways once the disease begins to take effect. We still have a lot to learn from this epidemic, in other words.'


http://www.guardian.co.uk/uk/2008/aug/03/bse.medicalresearch