People may develop "human BSE" up to 40 years after eating infected meat, says a scientist advising the government.

People may develop "human BSE" up to 40 years after eating infected meat, says a scientist advising the government.

The finding, based on studies of Pacific cannibals who developed a similar disease, also means the scale of the "vCJD" epidemic could be far worse than predicted, because it implies BSE-like agents can infect anyone.

Scientists had thought inherent genetic makeup could confer immunity against the disease for some people. But if anyone can develop vCJD, the eventual epidemic could affect 2.5 times as many as previously predicted,over a longer time.

"We may well see [cases of human BSE] well into the second half of this century," Professor Collinge of St Mary's Hospital in London said in New Scientist magazine.

Research by Professor Collinge on the cannibal tribes of Papua New Guinea - who used to eat the brains of deceased relatives as a mark of respect - found elderly people are still developing kuru, the CJD-like disease, more than 40 years after the practice was banned. Over the past 100 years, more than 2,500 members of the Fore tribe have died of kuru, which resembles vCJD.

Significantly, the latest people developing the disease have one of three specific genetic combinations on a gene which produces the protein implicated in kuru, BSE and vCJD. The possible combinations, or "genotypes" are called M-M, V-V and M-V. These occur respectively in 37 per cent, 12 per cent and 51 per cent of the population.

Everybody who has so far developed vCJD has had the M-M combination, found in only 38 per cent of people. Some scientists had suggested people with the two other combinations might be immune. But Professor Collinge said the 11 newest cases of kuru, in the oldest people, are affecting those with the M-V genotype.

"We're seeing lifetime incubation periods," said Professor Collinge, who is on the Spongiform Encephalopathy Advisory Committee, advising the Government on BSE and CJD.

Research with mice had suggested the M-V genotype, while not conferring immunity, would lead to longer incubation times. The kuru findings confirm that. Evidence of "classical" CJD, which seems to affect only people over 65 and has no known cause, show it predominantly affects people with the M-M genotype. They make up 80 per cent of cases, with the rest almost evenly spread between the V-V and M-V genotypes.

This suggests the M-M combination is particularly susceptible, which would explain why the first cases of vCJD have been in such people.

After the Phillips report into BSElast month, a aid package worth millions was set up to help families of victims of vCJD, but the Secretary of State for Agriculture, Nick Brown, said the Government did not have an estimate of how many would eventually die. So far nearly 90 have died of it since 1995. The numbers are expected to rise to hundreds or thousands over coming decades.