Traditional butchery practices in many small European slaughterhouses appear to increase the risk of spreading variant Creutzfeldt-Jakob disease (vCJD), the human form of mad cow disease. Five people in a village near Leicester, United Kingdom, probably contracted the disease this way, British scientists reported today at a special meeting of the regional health authority. Because the slaughtering techniques were common in many European countries where mad cow disease has struck, experts fear that many more vCJD cases will arise.
Since 1996, at least 95 people in the U.K. have died of a human version of mad cow disease, also known as bovine spongiform encephalopathy (BSE). Most scientists believe that vCJD can be caused by eating BSE-contaminated meat, but the link has never been firmly established. A chance for a breakthrough emerged in the last 2 years when five young people died of vCJD within 5 kilometers of Queniborough, a small village northeast of Leicester.
In search of the source of this disease cluster, Philip Monk, a communicable disease specialist with the Leicester Health Authority, and colleagues interviewed the relatives of the victims and of 30 age-matched people in the area. The team also focused on 22 local retail butchers and grocery stores. The first butcher they visited gave them a clue: He split a cow's head to remove the brains and sell them. Meat can "easily be contaminated" in this way with potentially infectious brain material, Monk says. Further questioning confirmed the suspicion: Four of the five victims--but only three of the 30 controls--purchased meat from four butchers who regularly used this traditional butchery practice, banned in 1989 in Great Britain. The vCJD victims were also 15 times more likely to have eaten meat from slaughterhouses that shot a bolt through a cow's brain, which can leak brain tissue onto the carcass.
This is the first evidence that vCJD is caused by meat contaminated during preparation, says Simon Cousens, a biostatistician at the London School of Hygiene and Tropical Medicine. "They've come up with a pretty plausible explanation," he says. Most European countries have recently banned these practices, but with an incubation time of 10 to 20 years, Monk says that "cases are likely to emerge in other countries with BSE at least until 2016."