'vCJD may take 30 years to show'

vCJD causes characteristic sponginess in the brain

The incubation period of variant CJD may be as long as 30 years, a leading scientist says.

Professor John Collinge, a member of the Spongiform Encephalopathy Advisory Committee (SEAC), which advises the government on BSE, said this could mean that thousands of people could eventually die from the human form of mad cow disease.

It is thought that vCJD is contracted by eating meat contaminated with BSE.

Professor Collinge's comments come the day after the publication of the official report into cluster of vCJD in the Leicestershire village of Queniborough, which claimed the lives of five people.

For me the main finding from this report is that the significant exposure appears to pre-date 1985

Professor John Collinge, SEAC

The report found that traditional techniques at small abattoirs linked to a handful of local butchers were the most likely cause of the cluster because they were most likely to lead spread the BSE agent to cuts of meat for human consumption.

The experts who carried out the study estimated that the incubation period of vCJD was likely to be between 10 and 16 years.

Chill down spine

But speaking on the BBC's Today programme, Professor Collinge said: "For me the main finding from this report is that the significant exposure appears to pre-date 1985.

"That sent a little chill down my spine, certainly. It fits with our estimates that we have been making of the likely incubation periods of BSE in humans.

"The cases we are seeing at the moment are by definition those with the shortest incubation periods.

"The average incubation period could well be in the region of 30 years."

Professor Collinge said a 30-year incubation period had implications for the likely toll of the disease on the human population.

He said: "Unfortunately what follows from that, since the exposure of the population after 1985 was very much larger than that that preceded it, (is that) many more cases must be in the pipeline."

However, Professor Collinge said that it was unlikely that the epidemic would run into six figures.

He said: "We may see thousands, or tens of thousands."