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Sunday, January 04, 2004
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SUMMARY OF THE FINAL REPORT OF THE INVESTIGATION INTO THE NORTH LEICESTERSHIRE CLUSTER OF VARIANT CREUTZFELDT-JAKOB DISEASE
The investigation was carried out by Dr Gerry Bryant and Dr Philip Monk who have prepared and present this report to Leicestershire Health Authority.
...# RESULTS OF THE CASE CONTROL STUDY
1. Butchers, supermarkets and freezer food centres used by cases and controls
Four of the people who developed variant Creutzfeld-Jakob Disease bought and consumed beef from one of two butchers during the early 1980s. One of these butchers slaughtered beasts in his own abattoir. This butcher normally processed three beasts a week. He ceased trading in 1989. The other butcher had beasts slaughtered in a small nearby abattoir. He processed four to five beasts a week. This butcher’s business ceased trading in December 1982. It has not been possible to trace the butcher who was used regularly by one family during the first half of the 1980s. It is unlikely that he removed brains or even purchased the heads of beasts. He did not slaughter beasts himself or use a small local abattoir.
...# CONCLUSIONS FROM THE STUDY
We have found an association which provides a biologically plausible explanation suggesting that four out of the five people with variant Creutzfeld-Jakob Disease may have been exposed to the BSE agent through the purchase and consumption of beef from a butcher’s shop where the meat could be contaminated with brain tissue. On a national basis, it is unlikely to explain how all of the people who have developed this disease were exposed to the BSE agent.
Assuming that we are correct in our explanation, we have shown that for one of the butchers, the exposure took place before December 1982. For the other the risk of the exposure continued until that butcher ceased trading in 1989. Analysis of the exposure of our cases to this butchering practice points to an incubation period for the development of variant Creutzfeld-Jakob Disease of between ten and sixteen years. This is the first time that it has been possible to provide an estimate of the incubation period.
We have shown that it is possible to examine by traditional epidemiological methods exposures that took place twenty years ago.