A NEW wave of deaths from the human form of "mad cow" disease is feared after scientists found a type of variant CJD never seen before.
Tests on the brain of a 39-year-old woman killed by vCJD, the human form of BSE, have aroused concern that the rate of deaths caused by the disease is set to escalate again.
Scientists who examined the brain found unusual patterns of damage, while the woman also had a distinct genetic make-up associated with her illness which was not shared by other victims. The worrying discovery suggests the woman might be the first of a new group of people succumbing to vCJD after eating infected beef in the 1980s.
Investigations are at an early stage and neurologists are being urged to look out for other cases of the disease to see if a pattern develops.
Dr Simon Mead, of the Medical Research Council's Prion Unit at University College London, which examined the woman's brain, said: "The final conclusion remains open.
"It is waving the flag for neurologists to watch for other cases."
More than 160 people are thought to have been killed by vCJD since it was first recognised in 1995. Research shows rates of the incurable disease are more than one-third higher in Yorkshire than in the South.
Symptoms of the disease, which is linked to misshapen prion proteins in the brain, affect people at different stages of life, depending on their genetic make-up. Experts believe the timer could still be ticking for many of those infected, with the incubation period exceeding 50 years in some cases.
The number of annual deaths from vCJD has been in decline since it peaked in 2000, when 28 died. In the year up to November 30, 2007, there were just four definite or probable cases.
But all these people had the MM version of the gene that makes prions; the woman examined in this latest case had a different gene variant, VV, found in about 10 per cent of Britons.
Researchers say she could be the first of a new wave of cases with the same genetic make-up who have only now reached the end of their incubation period.
Another possibility is that the woman had a rare form of "sporadic" or "classic" CJD which has nothing to do with mad cows or infected beef.
This appears less likely. She was relatively young, whereas most cases of sporadic CJD occur in people over 50, and the abnormal prions in her brain were typical of vCJD, not sporadic CJD.
Her case, described in the journal Archives of Neurology, suggests people with the VV gene variant could be next in the queue to fall victim to the disease after those with the MM variant.
Another variant, MV, is carried by half the UK population who may comprise the third wave of victims – if they live long enough.
A similar pattern was seen with kuru, a similar prion-related brain disease, which affected cannibals in Papua New Guinea.
Scientists have been puzzled for years by statistics which show a significantly higher risk of contracting vCJD in the North of England and Scotland compared to the South and Wales.
In October 2004 a report from the National CJD Surveillance Unit showed there had been 3.33 cases of vCJD per million people who were living in the region in 1991.
This figure was lower than for Cumbria (4.17), but far higher than for the West Midlands (1.79) and Wales (2.03).