London

Traditional butchery practices are the most likely cause of Britain's first cluster of variant Creutzfeldt–Jakob disease (vCJD) in the Leicestershire village of Queniborough, an official public health report concluded last week . The investigation into the deaths of five people from vCJD, the human form of BSE, also pins down the estimate of the disease's incubation period to between 10 and 16 years.

The inquiry team believes that the disease was probably spread as butchers split open the heads of infected cow carcasses to remove brain tissue, which can contain the BSE agent. This could have allowed the sticky, tainted tissue to be transferred to other cuts of meat from knives, hands, slabs and aprons. Removing brain tissue was popular during the Second World War as a cheap source of protein, but the practice was relatively rare in Britain during the 1980s and has since been banned.

Four of the five victims ate beef bought from one of two butchers who either slaughtered animals and removed the brains themselves or used a small, local abattoir during the first half of the 1980s, the inquiry found.

But Robert Will, director of the UK National CJD Surveillance Unit, says that the low number of cases involved makes it difficult to make more general predictions from this cluster. “These may be early incubation periods so what really matters is the mean period,” he says, adding that other cases of vCJD will almost certainly appear after much longer periods of time.