Mad Cow - CJD Species-Jumping
Revelation Confirms Worst Fears
By James Meikle,3604,360411,00.html
The revelation that BSE and its human form may be able to jump the species barrier and be highly infective even when a person or animal with the disease shows no signs of it, appears to confirm some of the worst fears scientists have about the fatal condition.
The disease, bovine spongiform encephalopathy, has already caused a cattle epidemic costing more than £4bn, and its human toll of 73 deaths so far - all except three being Britons - is climbing steadily. Its eventual impact on the health of the human population and the cost to the NHS, is almost impossible to measure. Yet when the cattle disease first emerged in 1986, government advisers dismissed any threat to people.
Now Europe quakes. Scientists believe that countries, such as Germany, which profess not to have BSE, are likely to have some cattle suffering from it even if the disease has not yet taken sufficient hold for it to be obvious. The first known case of BSE, in a cow on a farm in Pitsham, Sussex, occured in December 1984, almost two years before the disease was identified. In fact, the illness may have begun to set in during the early 1970s, but at such a low level that vets and farmers did not recognise it as a new disease.
Feeding practices, in dairy farms particularly, where cows' diets included the groundre mains of other cattle and sheep, probably sent the disease into its catastrophic spiral. Even now cases in Britain far outstrip those anywhere else. There have been more than 177,000 cases, nearly 780 confirmed so far this year. By contrast, Ireland has had a total of 489 BSE cases, Portugal nearly 350 and Switzerland 365.
France, with whom the beef war drags on ,has had just over 100 cases, with 28 this year. There have also been two cases of human BSE in that country and one in Ireland.
There have been numerous forecasts about the eventual human death toll. Some estimates, putting it at less than 100, already look too optimistic. Others have judged it be hundreds of thousands. Oxford statisticians earlier this month painted a worst case scenario of 136,000.
After years in which warnings of death through eating infected meat met public scorn, in March 1995 the fatalities began. But it was March 1996 before scientists made the first connection. The first victim to die was Stephen Churchill, aged 19, though the first person to show symptoms is thought to have been a 50-year-old, in January 1994.
Even now it is thought victims are most likely to have been infected by exposure to cheap meat-cuts from highly infective parts of cattle before the first anti-BSE controls to protect human health were in troduced in 1989. The agriculture minister, John MacGregor, banned the use of certain offal in food against the earlier advice of civil servants.
Even though the ban was not as rigorously observed as it should have been over the next six years, the measure probably stopped the collapse of the beef and dairy industries in 1996 when the link to human deaths was made, and reduced the prospects of a far worse human death toll from infected beef when BSE was at its height in the early 1990s. Other measures have been added, including from December 1997, for two years, a ban on selling beef on the bone.
Measures to stop humans spreading the disease have included changes to blood transfusions, the use of more disposable equipment and more rigorous sterilisation.
The problem for the government, even after the new findings suggesting human BSE might be spread more easily than had been assumed, is deciding just how much should be spent on seeking to prevent an unquantified risk.
The latest research means the assumptions - that a species barrier between humans and the animals they eat would cut the number of people who might succumb to BSE, and that there might have to be a high dose of infective material to induce the disease - must be re-addressed. Cows appearing healthy may also be capable of infecting people more easily than had been supposed. So scientists will have to consider whether they are removing enough offal from the food chain and whether barring cattle over 30 months for sale is sufficient. Cattle far younger than 30 months have displayed BSE signs - although not since 1996 - and the 30-month rule does not apply in many other countries that have BSE.
European-wide offal bans are only just being introduced, and scientists have suggested that just one cow slipping through the net could infect up to 500,000 people.
There is also the suggestion that transmission of BSE-like diseases through different species may create new, more virulent strains. Some scientists believe that scrapie, a BSE-like disease in sheep not known to be harmful to humans, is now disguising the BSE agent that has entered sheep through animal feed and been recycled through the generations. Scrapie-infected sheep brains are being tested with mice in the laboratories. Last month, the food standards agency suggested such a BSE-like strain might be identified "at any moment".
Contingency plans , including altering slaughterhouse and butchery practices, are already being prepared to try to avert another food panic. Britain does not routinely test for BSE in cattle planned for human food. And, unlike other countries, the UK does not destroy all the animals of a herd when a BSE case is identified.
Millions of cows over 30 months old have been destroyed under compensation schemes, and there is a suspicion that this has made it look as if BSE is dying out faster than it really is.
The recent research suggests cattle can harbour the disease it without showing outward signs of it. Random tests on 3,000 cows last year revealed 18 had BSE without showing clinical symptoms. Such checks will be increased to 10,000 this year and there will be surveys on 3,000 animals which die unexpectedly on farms or have to be slaughtered through illness or injury.
But ministers will have to consider whether also to check animals going into the food chain. That could improve consumer confidence - but not if the monitoring shows BSE is more widespread.
The government plans to follow France and Switzerland by introducing rapid cattle post mortem examinations from January with results in one to two days.
The problem is whether these will be sensitive enough to detect BSE in its early stages. Such measures would assume that the eating of infected meat has been the cause of variant CJD.
But billions of pounds-worth of preventative measures are already in place. And the question remains, how much more needs to be spent?

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