The first detailed study of a cluster of cases of variant CJD suggests that traditional methods of slaughtering cattle may have contributed to five deaths in Leicestershire.

The three men and two women fell ill between the summer of 1996 and the winter of 1999. All had lived in or around the village of Queniborough in the 1980s.

That, according to the experts, was a statistically significant number - and an epidemiological study began last July, shortly before the last of the five died.

As they tried to find links between the victims, the researchers ruled out any common experience of surgery, dentistry, vaccination, or occupation.

The five did not eat the same school meals, nor did they have milk from the same supplier nor water from the same source. Even body-piercing and animal-bites were investigated.

Slaughter methods have been linked to CJD cluster

Eventually, one plausible link was established: all had been consumers of beef and beef products, and had used small local butchers.

Dr Phillip Monk, Consultant in Communicable Infections for Leicestershire Health Authority, said the team had investigated the entire food chain, and had eventually concentrated their attention on the methods used by large and smaller abattoirs.

Techniques varied, with the smaller ones passing on whole carcasses, including the animal's head, to butcher shops.

He said once a carcass reached the butcher, the brain was removed as there was a commercial market for it at that time.

The local custom was to use a so-called pithing rod, which was driven into the spinal cord to prevent animals kicking out after they'd been stunned. This often broke the membrane around the brain, allowing infected material to ooze out. It was, he said, "an extremely tricky and messy process".

Dr Monk added that butchers also tended to wipe down, rather than hose down, after slaughter.

In cases where the animal had BSE, this could lead to other meat and knives becoming contaminated.

There was, it was stressed, nothing illegal about this process: it was a craft skill.

According to the Queniborough hypothesis, the risk arose when it coincided with the still unexplained development of BSE in cattle in the 1980s.

Leicestershire had a moderately high level of BSE cases: it's an important dairy area, and in dairy herds, calves for beef fattening were taken from their mothers at six days old and fed on meat and bone meal - now banned.

Arthur Beyliss, whose daughter Pamela died of CJD at the age of 24, speaking on behalf of five local victims' families, said it was ironic that he had always tried to protect his family by shopping at small local butchers.

But Mr Beyliss does not believe that today's report has eliminated all other possible sources of the human disease. He told me that he does not believe the research is conclusive.

Scientists like Dr Monk agree that the report is simply a pointer to the need for further research.

However, he told the World at One that lessons had been learned about the possible incubation time for variant CJD: from the cases studied by his team, the shortest incubation period was ten years, and the longest - sixteen years.

The deputy Chief Medical Officer believed that was an important finding. Dr Pat Troop said that she would now present these findings to the relevant expert committee to find out whether it helps understanding of the cause of the disease and the future course of the epidemic.

The committee would also be asked to consider whether or not any similar study should be carried out elsewhere in the country.