Two papers have concluded they have overwhelming proof a new version of Creutzfeldt-Jacob disease (vCJD), which has infected 21 people in the UK, was caused by eating BSE-infected meat.

The studies for the science journal Nature found vCJD and BSE - so-called "mad cow disease" - were caused by the same infectious protein.

And the research carried out on laboratory mice said the diseases had similar incubation periods and caused the same type of brain damage.

Scientists have also discovered the risk of humans becoming infected with vCJD depended on their genetic makeup.

Long incubation

All the British victims had a common combination of genes, called "M-M", which made them more susceptible to the brain disease.

Researchers calculated 38% of the population are in this higher risk group.

Professor John Collidge of Imperial College, London said the disease could have a long incubation period and so it was difficult to forecast what would happen next.

"If a relatively small number of cases occur over the next three or four years that's obviously good news."

"But it doesn't mean to say there might not be very much larger numbers further down in 10 or even 20 years later," he told the BBC.

Dave Churchill, the father of the first vCJD victim, has called for a further inquiry into the BSE crisis.

"We now know what happened - but we still need inquiries to find out the reason it happened," he said.

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