The inquiry team at Leicestershire Health Authority has reported on the results of the investigation into the geographical cluster of five cases of variant Creutzfeld-Jakob Disease (vCJD) around the village of Queniborough. The investigators have concluded that the purchase and consumption of beef in the early 1980’s from butcher’s shops where the meat could have been contaminated with brain tissue from cattle affected with bovine spongiform encephalopathy (BSE) provides a plausible explanation for the cluster (1). A case control study, in which relatives of the five cases and relatives of 30 age-matched controls were interviewed, found that cases were 15 times more likely than controls to have purchased and consumed beef from a butcher who removed brains from cattle (p = 0.0058, 95% C.I. for odds ratio 1.6 – 140).
The two butchers linked to four of the five cases removed the brains from cattle that were slaughtered either by the butchers themselves or in a nearby small abattoir. Pithing rods were used during slaughtering, and the carcasses were cleaned by wiping rather than by hosing. Removal of the brain was difficult and messy and the meninges were often ruptured either at removal or by the pithing rod. This led to a risk of cross contamination of carcass meat with brain tissue. Reasons are also given as to why during the early 1980’s the cattle in mixed dairy-beef herds used for the local meat trade may have had higher levels of BSE agent at slaughter than cattle raised for beef alone.
The practice of removing and selling the brains of cattle as food was legal in the United Kingdom throughout the 1980’s. Since 1989 it has been illegal for cattle brains to be used for human consumption and since 1996 the whole head of cattle over six months must be disposed of in a slaughterhouse as specified risk material.
The current number of definite and probable cases of vCJD in the UK is 97 (2). Of these, seven are probable cases who are still alive. Although there are other geographical areas with more than one case, to date Queniborough is the only area where statistical analysis suggests the association between the cases is unlikely to have occurred by chance.