A public health inquiry has blamed butchers' techniques for the spread of the brain wasting disease vCJD through the small middle England town of Queniborough during the 1980s.

Leicestershire Health Authority instigated the inquiry to look into the reasons why the town exhibited a cluster of cases.

By investigating the victims' eating and shopping habits, the inquiry aimed to piece together a picture of how the disease was contracted. It also looked into the techniques used at local abattoirs and butchers to see if BSE-infected material could have contaminated food supplies, the main method by which people are believed to contract vCJD

The conclusion came that the five victims most likely contracted the disease after eating brain tissue infected with BSE.

Two butchers shops in the village, which have since closed down, were discovered to have employed traditional methods in processing animal carcasses; techniques that were centuries old and have since been made illegal. They were found to have removed the brain to recover meat from the head, thus increasing the chance of contaminating the rest of the carcass with BSE infected material.

Because the full extent of BSE was still not known during the early 1980s, the butchers were also found to have used knives between beasts without cleaning them at this time.  

At local abattoirs, slaughter men used a pithing rod to prevent animals already stunned with a "captive bolt stunner" kicking reflexively. The EU banned the use of the pithing rod last year, after fears were raised that it could spread material from the brain and nervous system to the rest of the carcass.

Furthermore, during the time the victims contracted the disease, it was not a legal requirement that carcasses were hosed down. Many of the local processing units merely wiped the meat down with a cloth, believing that this method was preferable because it did not make the meat go "sour." It did, however, increase the chances of spreading contaminated material around the carcass.

The report was welcomed by the Department of Health and is noted for providing the most conclusive evidence to date that vCJD can be contracted through the consumption of BSE-infected material. "This result is statistically significant and is therefore very unlikely to be a chance finding," it concluded, pointing out that when compared to a control match group, the vCJD victims were 15 times more likely to have consumed beef that had been processed in methods as above.

The findings cannot definitely explain disease transmission in the remainder of Britain's 97 vCJD cases, however. CJD expert Simon Cousens, from the London School of Hygiene and Tropical Medicine, said the report is  "an extremely thorough study" but argues that forecasts cannot be accurately made on the spread of vCJD on the basis of the Queniborough conclusions.

Surprisingly little is still known about the transmission of vCJD, and official estimates concerning the number of cases Britain can expect to witness ranges between 200 to many thousands. The most important question mark hangs over the length of the incubation period. The Queniborough victims died five years ago, between ten and 16 years after they are believed to have contracted vCJD, but this may not be typical.

The Department of Health has asked Seac, the BSE/vCJD advisory group, to conduct further research in a bid to follow up on the Queniborough findings.

By Clare Harman, just-food.com editorial team