It may be five or ten years before the rest of the population of those at risk develop the disease. Professor John Collinge

Professor John Collinge is one of the government's top advisors on vCJD and director of the Medical Research Council Prion Unit in London.

He has found that a small number of the mice he observed got vCJD fairly quickly while the rest had a longer incubation period before contracting the disease.

"I don't want to be alarmist about this," he said "but it's entirely possible and we have to consider that what we are looking at, at the moment is, thankfully, a very small incidence of the disease amongst a small sub-section of the population. It may be five or ten years before the rest of the population of those at risk develop the disease."

Official estimates predict the final death toll from the disease could be as low as 150 or as high as 136,000.

Number of CJD deaths rising

The number of deaths from vCJD has steadily increased over the last five years - from three in 1995 to 29 in the year 2000. This year 15 cases have already been confirmed.

No-one knows when the disease will reach its peak.

Variant CJD is a degenerative brain disease in humans which is thought to be caused by an abnormal prion protein in the brain. Its most likely origin is exposure to the BSE prion from eating infected beef. Only genetically susceptible people - about 40% of the population - are thought to be capable of getting the disease.

The average age of those who have died is 28, and only a handful of victims have been older than 53.

In contrast, 93% of people with "classic" CJD, which occurs sporadically for no known reason and is unconnected with contaminated meat, are over 50.

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