Analysis of organs predicts possible 7,000 CJD deaths

More than 7,000 people could die from variant CJD caused by eating food infected with BSE, an analysis of organs removed from hospital patients suggests today.

More than 7,000 people could die from variant CJD caused by eating food infected with BSE, an analysis of organs removed from hospital patients suggests today.

A team of scientists from Derriford Hospital in Plymouth and the National CJD Surveillance Unit in Edinburgh tested 8,318 appendixes during the 1990s. One tested positive for the vCJD protein "signature", giving an "estimated prevalence" among the population of 120 cases of vCJD per million. With the UK population about 60 million, that would mean 7,200 deaths.

The scientist leading the study said that there were too many uncertainties about the accuracy of the tests to be sure of the study results.

In an attempt to obtain a better estimate of the eventual death toll from the disease, which has so far killed about 115 people, the Department of Health is preparing a study of thousands of tonsils extracted in hospitals.

Estimates of the numbers who could die have ranged from between 1,000 and 80,000, in a scientific paper published in January 1997, to guesses of millions by some who reckoned almost everyone in the UK had eaten BSE-infected material at some stage. Yet although six and a half years have passed since Stephen Dorrell, Health Secretary at the time, told Parliament that BSE and vCJD seemed to be linked, scientists and doctors are still wrestling with the question of when they will have enough information to predict the course of the epidemic accurately.

Variant Creutzfeldt-Jakob disease, known as vCJD, is a fatal, incurable brain disease with an incubation period that may range from a few years to many decades, during which one shows no symptoms. BSE, bovine spongiform encephalop-athy, was first spotted in British cattle in 1986, and the first case of vCJD in 1994. Nobody knows the maximum incubation period; a similar disease, kuru, has shown 40-year incubations. The onset of symptoms leads to a rapid deterioration when the brain is damaged by "plaques" of insoluble protein.

Dr David Hilton, who led the new research, published in the British Medical Journal, cautioned that there were still too many uncertainties to be sure of the final figure, and whether the 120 per million was a reliable guide. "It would be dangerous to jump to that conclusion," he said. "The reliability of the test we used on the appendixes is unclear for humans, though it seems good in animals."

Professor Peter Smith, who chairs Seac, the committee that advises the Government on BSE and CJD, said: "This is an interesting finding, which does give some limited reassurance [about the eventual death toll]. There were fears that, as most of us have been exposed to BSE, that there might be a large number of people with it.

"This doesn't rule it out, because we don't know when in the disease it starts to show up in the appendix."

Epidemiological studies last year by Professor Smith, published in the journal Science, said predicting that the epidemic would be larger than a few thousand was "difficult".

That comes with caveats, though. So far all vCJD victims have belonged to a particular genetic type, found in about 40 per cent of the population. Nobody knows if the other 60 per cent are immune or just have a longer incubation period; and nobody knows if there was a minimum BSE exposure for successful infection, or exactly how much BSE-infected food was consumed, and by whom.