May 21, 2004 DAILY MAIL (London) by JENNY HOPE

Scientists believe as many as 3,800 victims, mostly aged 30 or under, could be involved.

The condition, Creutzfeldt-Jakob Disease, which can lay dormant for decades, has claimed as many as 141 lives over the past nine years.

Now the researchers' prediction - believed to be the most accurate yet - has prompted calls for greater vigilance to prevent the disease from being transferred via blood transfusions or organ donation.

But they say many victims may never actually develop the fatal brain disease because - despite the growing number of positive cases - infection rates are going down.

Professor James Ironside, senior pathologist at the National CJD Surveillance Unit in Edinburgh, said: 'There are more positives than you would expect, given the number of vCJD cases and the fact they seem to be declining.

'I think the findings do have to be taken seriously.' The study - carried out at Derriford Hospital in Plymouth and

published today in the Journal of Pathology - examined 12,674 appendix and tonsil tissues removed during routine surgery and stored at hospitals.

Most were from patients in the 20 to 29 age group who are at greatest risk of developing the disease.

Three were found to contain abnormal prion protein molecules, believed to be the agent which triggers vCJD. Scientists then extrapolated the results to find a nationwide figure.

But some experts fear it could go much higher.

Professor John Collinge, head of the Medical Research Council Prion Unit at St Mary's Hospital in London, said the results could be unreliable because the vast majority of samples examined were from appendices, which are much less sensitive to vCJD infection than tonsils.

He said: 'I find these results very concerning. Our experience is that looking at appendix samples will underestimate the true picture.

'In addition, no test is going to be 100 per cent effective and you don't know at what stage in the incubation period the test will be positive.' Study leader Dr David Hilton, from the department of histopathology at Derriford Hospital, said: 'Our findings need to be interpreted with caution but cannot be discounted.' There have been doubts about the scale of the threat posed by vCJD since it was first identified in 1995.

Some experts have warned of up to 500,000 victims while others believe they will only number in the hundreds.

Since 1995 there have been 141 definite or probable deaths in Britain.

Last year there were 18.

A Department of Health spokesman said steps had already been taken to reduce the chances of transmission.

These include a ban on anyone who giving blood who has received a blood transfusion since 1980.

The spokesman said: 'The results reinforce the need for a continued precautionary approach to minimise exposure to vCJD.'