The figures show that the epidemic doesn't appear to be worsening

Dr Azra Ghani, Imperial College

So far, there have been just over 100 deaths in the Britain that were either definitely or probably caused by the disease.

Uncertainty over the incubation period of the vCJD means that scientists cannot put forward any reliable prediction on how many could eventually be affected.

So far, the estimate ranges from only a few hundred to as many as 140,000 cases.

Dr James Ironside, from the National CJD Surveillance Unit in Edinburgh, told last week's British Association meeting in Glasgow that there had been between a 20% to 30% surge in the number of cases over the past few months.

Blip debate

He suggested that the upper limit on the estimate of cases might have to be revised as a result. He said: "We've had blips before... this is not a blip.

"Moving from a flat pattern, we're now seeing an upward change. This is a sustained pattern."

However, Dr Ghani, from Imperial College in London, said case numbers had actually stabilised over the past year.

She told New Scientist magazine that Dr Ironside had been examining figures comparing 1999 with 2000, rather than more current figures.

In the 12 months leading up to August 2001, 17 cases were reported. The previous 12 months to August 2000 saw 19 cases emerge, while the year up to August 1999 saw just six cases.

Dr Ghani said: "This year the incidence of cases pretty much mirrors last year. The figures show that the epidemic doesn't appear to be worsening."

She said that the projections for the eventual number of cases were unlikely to be revised upwards or downwards in the light of the latest figures.