August 6, 2004 The Herald (Glasgow) by Helen Puttick

The illness, which seemed to be diminishing, could actually represent a hidden time bomb, according to new evidence about the disease.

The discovery of the infection in a patient with a different genetic make-up to all previous victims has sparked the concern. It means instead of 21.8 million potential carriers in the UK, there are more than 51 million.

Carriers could unwittingly infect others by donating blood and, should they need medical treatment, by contaminating surgical tools.

Two people who received blood from blood donors who later developed vCJD have now died. In the second case, investigated by members of the National CJD Surveillance Unit in Edinburgh, the victim did not die from the condition, although a post-mortem examination revealed the agent responsible for causing vCJD was present in the patient's spleen and lymph node, but not in the brain.

This was despite the patient not having two matching genes known to be susceptible to the infection. Until now, only people in this genetic group (MM), which is one of three and accounts for around 37% of the population, have suffered the illness.

But the post-mortem has proved people in the largest genetic group with a different genetic pairing (MV), which represents 50% of the population, can also become infected. The finding raises the possibility that vCJD has a much longer incubation period in the second grouping.

Professor James Ironside, director of the national surveillance unit, said: "This finding has major implications for future estimations of numbers of vCJD cases in the UK, since individuals with this genotype constitute the largest genetic subgroup in the population.

"It's absolutely possible that there may be a new epidemic, because the cases we've seen so far may only be those who are unusually susceptible or have the shortest incubation periods. I'm not in the business of scaremongering, but quite clearly the idea that this problem is on the way out is unfortunately not the case at all."

However, Professor Ironside said it was significant that the elderly patient did not die from vCJD and the infection would never have been detected without a post-mortem.

Frances Hall, secretary of the Human BSE Foundation, whose son Peter died from the illness in 1996, said the possibility that many more people could contract the disease was frightening.

A ban on anyone who has received a blood transfusion giving blood was introduced in March this year. However, there is no screening test that can detect the infection.

While plasma is imported for the manufacture of blood products, patients who undergo a blood transfusion generally receive UK-donated blood.

This is put through a procedure whereby white blood cells are removed to reduce the risk of vCJD transmission. However, another research paper, published in the Lancet today, suggests this system may not be as effective as hoped. US researchers testing the system in hamsters with scrapie, a similar disease to vCJD, found that it only reduced infectivity by 40%.

On a more positive note, a new technique for disinfecting surgical instruments contaminated with the deadly molecules that cause the human form of BSE was also unveiled in the journal.