'MAD COW DISEASE' KILLS 10,000 CATTLE IN BRITAIN;   LIVESTOCK: THE GOVERNMENT SEES ONLY A REMOTE RISK TO HUMANS. THE MALADY MAY BE SPREAD THROUGH CATTLE FEED.
"Mad cow disease" has killed 10,000 cattle, restricted the export market for Britain's cattle industry and raised fears about the safety of eating beef.   The government insists that the disease poses only a remote risk to human health, but scientists still aren't certain what causes the disease or how it is transmitted.   "I think everyone agrees that the risks are low," says Martin Raff, a neurobiologist at University College, London. "But they certainly are not zero. I have not changed my eating habits, but I certainly do wonder."   Mad cow disease, or bovine spongiform encephalopathy, or BSE, was diagnosed only in 1986. The symptoms are very much like scrapie, a sheep disease which has been in Britain since the 1700s. The incurable disease eats holes in the brains of its victims; in late stages a sick animal may act skittish or stagger drunkenly.   The suspicion is that the disease was transmitted through cattle feed, which used to contain sheep by-products as a protein supplement.   The government banned the use of sheep offal in cattle feed in June, 1988, and later banned the use of cattle brain, spleen, thymus, intestines and spinal cord in food for humans. Sheep offal is still used in pig and poultry feed.   In March, the government announced that it would pay farmers 100% of market value or average market price, whichever is less, for each animal diagnosed with BSE.   "I think it is a recognition -- not just of pressure from farmers -- but that the public would feel more confident that no BSE-infected animal would ever be likely to go anywhere near the food chain if there was 100% compensation," said Sir Simon Gourlay, president of the National Farmers Union.   The disease struck one of his own cows, Gourlay said. "In the course of 24 hours, the animal went from being ostensibly quite normal to very vicious and totally disoriented."   As of Feb. 9, the Ministry of Agriculture, Fisheries and Food said that 9,998 cattle have been destroyed after being diagnosed with BSE.   The government has paid $6.1 million in compensation, and is budgeting $16 million for 1990.   Ireland's Department of Agriculture and Food said about 20 cases have been confirmed there, all of them near the border with the British province of Northern Ireland.   Because of the disease, the U.S. Department of Agriculture's Animal and Plant Health Inspection Service in July banned imports of cattle, embryos and bull semen from Britain, said Margaret Webb, a USDA spokeswoman in Washington.   Similar embargoes have been imposed by Australia, Finland, Israel, Sweden, West Germany and New Zealand, according to the Agriculture Ministry, and the European Community has proposed a ban on exports of British cattle older than 6 months.   David Maclean, a junior agriculture minister, has complained of "BSE hysteria" in the media and has insisted that the risk of the disease passing to humans is "remote."   The government has committed $19 million to finding the cause of the disease.   A commission chaired by Sir Richard Southwood, a professor at Oxford University, reported last year that the cause of BSE "is quite unlike any bacteria or known viruses."   The report said the disease is impossible to detect in apparently healthy animals because it does not prompt the immune system to produce antibodies.   The Southwood report said it is "most unlikely" that the disease poses a threat to humans. But the report added: "If our assessments of these likelihoods are incorrect, the implications would be extremely serious."   There is a human variant of spongiform encephalopathy, known as Creutzfeldt-Jakob disease. About two dozen cases were reported in Britain last year.   Another form, known as kuru, had been found in cannibals in New Guinea.   According to a report in the British Medical Journal, the incidence of Creutzfeldt-Jakob disease is no higher in Britain than it is in countries free of scrapie.   "It is urgent that the same reassurance can be given about the lack of effect of BSE on human health," a consultative committee reported to the Agriculture Ministry. The committee's report, released early this year, said it is only a "shrewd guess" that BSE is transmitted through sheep offal in cattle feed.
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