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Research suggesting that the French have suffered an equivalent exposure to BSE infected beef as the British without a commensurate incidence of vCJD might yet throw some light onto the supposed relationship between these two diseases.(750 words)

A causal link between the emergence in the UK in the mid 1990's of Variant Creutzfeld-Jakob disease (vCJD), a rare but fatal brain wasting disease, and the Bovine Spongiform Encephalopathy( BSE), or mad cow disease, epidemic which began about ten years earlier is widely supposed.

More than £122 million has been spent on BSE research in the UK, much of it on infectivity, since March 1996 when the possibility of the connection hit the headline as the result of a poorly worded news release by the UK government's Spongiform Encephalopathy Advisory Committee. But the evidence essentially remains circumstantial. Both are brain wasting diseases probably caused by similar organisms known as prions. Variant CJD emerged after a suggestive incubation period after BSE was identified as a disease. And both, at the time, appeared to be exclusively British.

The issue is, of course, a very difficult one to research. The incubation of vCJD occurs over many years, beef is almost universally consumed and hence it is impossible to relate incidents of vCJD with eating beef, leave alone infected beef. With ailments caused by such organisms as salmonella and E coli, the incubation period is short and the source of infection is usually found festering in some waste bin.

Further, as vCJD is fatal and there are no known cures, experimentation involving large number of volunteers eating BSE infected beef and waiting ten years or so for an outcome is beyond the reach of any conceivable research budget. It, therefore, seems that the question of whether BSE caused vCJD will never be definitely answered.

But the experience of the French with their BSE epidemic which has not as yet resulted in a commensurate incidence of vCJD could throw further light on this question.

An article by two French academics in the June 2004 Veterinary Research journal suggests more than 300,000 cows were probably infected with BSE in France between 1980 and 1997. Just 26 were reported. It further suggested the epidemic in the late 1980 went undetected, resulting in the delay of the implementation of precautionary measures.

The research involved making projections from reports of BSE based on passive clinical diagnosis and on active and mandatory surveillance. Since 2000 this has covered all cattle at risk, essentially "downers," and cattle more than 30 months of age entering the food chain.

The article suggests that only 47,300 late-stage BSE infected animals were slaughtered for consumption before the French specified-bovine-offal ban in June 1996. These cattle are most likely to be a source of vCJD infection, if there is a causal link between BSE and vCJD. It is, of course, these unreported cases that enter the food chain rather reported cases that are critical in the context of vCJD.

In the UK there was a positive incentive for farmers to report, only diagnosed cattle were slaughtered and market value paid. For cattle slaughtered but mis diagnosed in the context of post mortem examination, a subtantial bonus above the market value was paid. In France the whole herd was slaughtered and the farmer lost his livelihood, even if he did receive market value compensation. Hence there was an incentive to avoid detection.

While the reported incidence of BSE in the UK was many times that in France, the probable incidence of infected beef entering the food chain was almost certainly more even. And, while the British imposed a specified offal ban in 1989 which resulted in the most infective parts of carcases being removed, the French did not take the same precaution until 1997.

There have been almost 150 cases of vCJD reported in the UK, but just five in France. This seeming anomaly would appear worthy of research.

There may, however, be challenges with such research over the level of reporting of vCJD in the two countries. By the time vCJD emerged as an issue, BSE had been front page news for the press and media for a decade. Hence, there was no place for politicians to hide.

Only with active surveillance, started in 2000, has it become accepted politically that France had a major challenge with BSE. Further, there is the potential in France for elected officials to be judged personally liable for mis administration.

And, in this context, until the causal link between BSE and vCJD is established, there is unlikely to be any indisputable evidence that there has been any under reporting of vCJD in France.

July 16, 2004