Mad about cow disease: Scares over beef continue to hit the headlines, but the truth is that no one knows the dangers, says Steve Connor

VICKY RIMMER, a 16-year-old schoolgirl, apparently normal and healthy only a few months ago, is lying critically ill in hospital. She has a progressive degeneration of the brain which has left her deaf, blind and unable to speak. Her plight was highlighted last week in the Daily Mirror (after an earlier feature in Today) and, on Wednesday night, in Channel 4's Dispatches programme.

The Mirror's headline was: 'Mad cow tragedy blamed on hamburger'. Vicky, the paper reported, was suffering from Creutzfeld-Jakob disease (CJD), the human equivalent of bovine spongiform encephalopathy (BSE) or 'mad cow disease'. According to her grandmother, who brought her up, Vicky loved meat, particularly burgers. But ministers have repeatedly insisted that there is no risk to humans from eating beef. In a leader, the Mirror accused them of a cover-up.

So what is the truth? Professor Richard Lacey, a medical microbiologist at Leeds University, argues that Vicky's case is 'ominous'. He predicts there will be between 50,000 and 5 million deaths from CJD in the next five years. He bases his estimate on the assumption that 1 per cent of people who have eaten beef or beef products from infected animals may suffer from the disease.

But Professor Lacey is virtually a lone voice among scientists. Most take a far more cautious view. CJD, which is incurable and leads to death within months, is extremely rare - so rare, says Dr Kenneth Calman, the Government's chief medical officer, that 'most GPs and hospital doctors are unlikely ever to come across a case in their entire working life'. There are about 50 new cases a year in the UK and, worldwide, there have been only three confirmed cases of teenage sufferers.

Confirmation is the difficulty. Scientists can only be certain of a case of CJD after death: a post- mortem examination of the entire brain is necessary to show the 'spongy' holes also seen in the brains of cows that have BSE. However, doctors often categorise some patients as 'probable' sufferers from CJD. They have the clinical symptoms - such as unsteadiness, poor sight and impaired speech - and the 'brainwave' patterns - electrical discharges - typical of the disease. About 95 per cent of these patients turn out to have CJD.

But Vicky does not fall into the 'probable' category. She appears to have only the clinical symptoms. Scientists call these 'possible' CJD sufferers; and fewer than half eventually prove to have CJD.

But even if Vicky does turn out to be suffering from the disease, it still tells us little about the cause. Whether or not she has eaten many burgers, science has to look further for a causal link. The Dispatches programme claimed that it had such evidence. It quoted information, published last year in a report compiled by Dr Bob Will, head of the CJD Surveillance Unit at Edinburgh, showing that eight farmers had also developed CJD. This sounds damning until you learn that only one had BSE in his herd. (Five worked on farms long before BSE was a problem.) Since the report was published, a second such case has become known.

Dairy farming involves about 115,000 workers and even one case, discovered in the first two-and-a- half years of CJD surveillance, is far greater than would be expected from the national trend. But the statistics are too small to draw reliable conclusions. In the UK, art teachers also appear to be at a higher than average risk of developing CJD. In France, nuns and priests are three times more likely to die from the disease than the public. There are no apparent reasons, other than a quirk in the statistics.

If the figures are inconclusive, do scientists know enough about how CJD is caused to tell us whether beef may have a role? They know that there is an inherited form of the disease, and that some people have contracted CJD because they were infected during medical treatment - for example, children given growth hormones derived from human donors who unknowingly had CJD. But most cases remain a mystery. For generations, a small number of people have suffered from CJD, even in countries where there have been no known cases of BSE or scrapie, which is a similar disease affecting sheep and goats. One clue is a structural change in a protein found in the brain.

But didn't a complete menagerie at London Zoo develop 'spongy' brain diseases through eating contaminated feed? Didn't cows get the disorder in the first place from food enriched with carcasses of dead sheep afflicted with scrapie? And if cows can get the disease from eating sheep and other animals, including the domestic tabby, why can't we contract it from eating infected cows? What makes us so different?

The answer is that we are not different. Dr Chris Bostock, a BSE expert at the Institute of Animal Health at Compton, Berkshire, says: 'It is not possible to allay fears, to say absolutely that it's a scientific impossibility for an infectious agent to be present in some meat products.' But Dr Bostock is happy to eat beef himself and advances several reasons why he can do so without suffering from sleepless nights.

First, no matter how hard researchers have tried, it has proved impossible to transmit scrapie or BSE from the muscle tissue of infected livestock into mice or other laboratory animals. Indeed, only the brain and spinal chord have sufficient quantities of the infectious agent to enable laboratory transmission, and these have been banned from human consumption since 1989.

Second, sheep scrapie has existed in Europe at least since the 18th century. Yet in all this time it has never been implicated in human disease. A few years ago there was a suggestion that Libyan Jews, who are 100 times more likely to suffer from CJD than the worldwide population, could have become victims of sheep scrapie because of their culinary habit of eating lightly cooked sheep brains. Further research, however, showed that this close-knit ethnic group carried the same mutation in the gene implicated in the inherited form of CJD.

So certainty is for politicians, such as John Selwyn Gummer who, as Minister of Agriculture at the height of the BSE scare, insisted that beef was perfectly safe and was photographed trying to feed a hamburger to his daughter to prove it. Scientists proceed by trial and error, waiting patiently for evidence. The case of Vicky, who has not yet been diagnosed as suffering from CJD, comes closer to the predictive nonsense of the astrologer than to anything scientists would regard as evidence.

All anyone can say at present is that CJD is an extremely rare illness and that there is no firm evidence that it has anything to do with eating beef. What is certain is that there is no cover-up by scientists such as Dr Will. On the contrary, by the normal scientific criteria, Dr Will's paper on farmers with CJD might not have been published. Several science journals turned down his research on the grounds that he could not demonstrate any causal link. But he persuaded the Lancet to publish his paper precisely because he thought it important to counter any suggestions of a cover-up.

The Mirror insisted last week that the Government 'must let all the facts be known'. All the facts available to scientists are known. Dr Will's concern is that this policy will lead to more alarmist reports like those last week. 'We will turn up oddities, I'm sure. My worry is that there is already a tendency to over-interpret something. Many of the issues are complex and trying to explain them in soundbites is difficult.'

The public is justifiably wary of the beef industry, and in particular those who allowed the abuse of natural laws by feeding dead sheep to cows. But scientists have no motive for playing down the link between BSE and human CJD in order to pander to the beef export business.

If the pessimists such as Professor Lacey are right, then they will be proved so within the decade. Politicians may well want to cover things up - but we should trust scientists, rather than emotional newspaper headlines and television programmes, to tell us the truth.

(Photograph omitted)