The likelihood of an epidemic of the human form of BSE is small, researchers from Imperial College London say today.

They predict about 70 more cases caused by eating infected beef in the 1980s and 90s, although they concede that there could be as many as 600 deaths from the incurable condition if all genetic groups are affected.

So far, 148 people in Britain have died from the fatal but long-incubating disease since 1995 and five are still alive.

The estimates published in the journal of the Royal Society, Interface, are far lower than the 3,800 suggested last year after a study of tonsil and appendix samples.

Azra Ghani, based at St Mary's hospital, London, said: "One reason for the discrepancy between the high estimated number of positive tests and low number of actual recorded clinical cases could be that many infected individuals do not go on to develop clinical disease in their lifetime."