They said 'it doesn't mean a thing'

The Government ignores the latest findings on CJD, BSE and scrapie at its peril, argues Emily Green
Click to follow
The Independent Online
At 11.11am Wednesday morning the Press Association put out a story that, 16 months ago, could have poleaxed the British sheep industry. It reported a letter in the new edition of Nature describing an experiment in which a form of synthesised human protein spiked with scrapie - the sheep analogue of mad cow disease - achieved a similarly positive reaction as material spiked with BSE. In other words, the suggestion hung in the air that scrapie might be as infectious to humans as BSE.

What? Just when the nation had given up hamburgers for doner kebabs? Yes. However, this is not to say that those who ate either are doomed. Rather, this new finding may prove another indicator of just how grossly we overdosed our dairy cows with meat and bone meal. That, and, given the failure last week of the Ministry of Agriculture to appreciate the significance of the Nature correspondence, it is rather as if Concorde narrowly missed the NatWest tower without air-traffic controllers noticing.

The former government would have spotted the ramifications and probably tried to clamp silencers on the Briton among the authors, Dr James Hope of the Institute of Animal Health in Berkshire. The logic: bad PR for British sheep is bad for Britain. At the height of summer, the UK has in excess of 40 million sheep, more than one sheep for every two humans. The industry is worth pounds 1.6bn.

This big market is a nervous one. One hypothetical starting point for bovine spongiform encephalopathy is scrapie, and one of the many gloomy discoveries of the mad cow saga has been that sheep and goats are susceptible to this newcomer, BSE. Still, even last year, at the height of controversy, the British export market in sheep was worth pounds 300m in carcasses, and pounds 40m in livestock.

One might have expected, therefore, at the very least, that the Ministry of Agriculture would have prepared a briefing. No such foresight. "It doesn't mean anything," snarled a press officer of the Nature case. She was quick to emphasise that the ministry had co-operated with the research by lending the scientists material, and that it was aware of the results. She is wrong, though, to suggest these "didn't mean anything".

On the contrary, they mean quite a lot. The area of in vitro conversion of PrP protein is rarefied. The new work - using synthesised normal protein and achieving limited but detectable conversion to abnormal protein when exposed to diseased starter cultures - is just one piece of the complicated scientific puzzle that is BSE/ scrapie/CJD research. While it is a small piece, it is perfectly formed and, rightly or wrongly, it is just this sort of scientific pinhead on which we are balancing our multimillion-pound meat industry.

The new work involves a fast technique - test-tube conversion - whose results appear to tally with existing knowledge gleaned from painstaking animal experiments. The researchers found that BSE corrupted cattle protein more energetically than it corrupted human protein, and that, where it reacted within two types of human protein, it did so more efficiently within the genotype shared by the 19 UK victims of new variant CJD. Bad news for the (roughly) half of the population sharing this genotype? Possibly. Except that all the reactions were limited. So this chain reaction between BSE and human protein, and its relative inefficiency, caught the imagination of the news agencies. "BSE can jump species barrier - with difficulty" was the Press Association flag.

The suggestion that scrapie might be as efficient (or inefficient) as BSE could be construed as good news. There were 453 confirmed cases of scrapie in the UK last year, and the disease has been incipient in British flocks and across Europe for hundreds of years, yet successive studies by epidemiologists have not been able to detect a relationship between it and sporadic CJD in humans. The latter is just as high in countries where there are few sheep (Israel) as where there are lots of sheep but no scrapie (Australia and New Zealand).

However, the Nature letter is hardly equating BSE with scrapie. There are many strains of scrapie. And what happens in a test tube is not necessarily an accurate indicator of what happens in us. Even if it were, it certainly does not mean we are at the same risk from scrapie as BSE. As the letter stresses, there are a great deal of other factors involved in the efficiency of infection, not least route of infection and dose.

When it comes to BSE, Britain had quite a dose. From the early 1980s, on average, the percentage of meat and bone meal in British dairy feed rose from 1 to 4 per cent, as feed companies promoted new methods to "steam up" British dairy herds before outputs were capped by milk quotas. As Dr Stephen Dealler insisted for years, and Oxford epidemiologists last year calculated, more than a million cattle infected with BSE, most of them clapped-out dairy cows, may subsequently have been sold as human food. Until the specified bovine offals ban of 1989, the most infectious organs of high-risk dairy cattle were freely consumed.

More than a year after the BSE crisis, SEAC, the government's scientific advisers on mad cow and related diseases, remains insistent that mad cow disease be viewed as the most likely cause for the new variant of CJD. Almost every scientist working in the field privately suspects BSE from offals eaten before 1989 is the culprit. One protein chemist I interviewed brashly bet his daughter's life on it.

Still, the same scientists are privately revising downward the scale of the predicted new variant CJD epidemic. Professor John Pattison, dean of University College London Medical School, took over as chairman of SEAC in November 1995. Four months later he was worried enough by early evidence to lead the scientific showdown that helped trigger the BSE crisis. "We don't have any increase of the rate at which nvCJD is occurring," he says now. "The possibility that there might be hundreds of thousands of cases is very remote. I have personally discounted it."

So it seems altogether unlikely that we will succumb to scrapie in the way 19 Britons have probably been affected by BSE. Yet, as our European partners continue to buy our sheep and now face BSE outbreaks in their own cattle, and we wait anxiously for trade to resume in British beef, the Ministry of Agriculture should have the wit to be constructive and honest in how it declares British experience. To respond to inconvenient results by saying "it doesn't mean anything" is not the way forward.

The writer holds the 1997 Glaxo Wellcome Association of British Science Writers' Award for feature-writing in a national newspaper.