THE BSE plague will continue to affect British cattle until the next century, according to a team of Oxford scientists. Although incidences are falling, there could still be 24,000 new cases in the next five years, according to their research.
Team leader Dr Martin Nowak published the findings in today's Nature magazine, just as a major cull of British cattle starts. The first animals were slaughtered at a Scottish abattoir on Saturday as part of Britain's efforts to control the disease.
In 1988, in an earlier effort it banned the use of ruminant material in cattle feed. But there have still been 28,000 confirmed cases of BSE in animals born since that ban.
"There is now no doubt that these were due to the continued use of contaminated feed," Dr Nowak said. This could have been because farmers used feed manufactured before the ban or because the feed was contaminated during manufacture.
Until recently, ruminant material was allowed in pig and poultry feed which is made on the same equipment as cattle feed. There is now little doubt that some cattle feed was contaminated as a result. Two months ago, the British government banned the use of ruminant material in any animal feed, finally closing off one more possible route for infection.
There have been more than 160,000 BSE cases in Britain. The numbers peaked in 1992, when 700 cases a week were being diagnosed. This year the numbers are closer to 70 a week.
Dr Nowak and his colleagues analysed the incidence of BSE among cattle of various ages and from these data predicted the numbers they expect in future years.
"There is a clear decline in the number of cases, and this reflects the fact that the (1988) ban is becoming effective. And that trend is set to continue. But we are still predicting some 15,000 cases, and maybe even 24,000, over the next, five years, and most of these will have been born after the ban.
He also predicts 1,000 new, cases in 1999 and 500 in 2000. "Overall, it's an extremely high figure, and there's no excuse. But the worst is over", he said.
On a more positive note he added that the figures could be lower if the culling programme was effective, since the calculations do not take account of culling. But Dr Nowak was cautious about the value of the cull.
"There will have to be a huge amount of culling to prevent the 15,000 cases we're predicting, and you have to remember that we have already had 150,000 cases. That huge epidemic is already fading."
Dr Nowak's colleagues include Sir Richard Southwood, the former chief government adviser on BSE from 1988-90, who is reported as saying previously that he favoured a complete cull of all animals born before 1991.