John Wilesmith, an epidemiologist at the Weybridge Veterinary Laboratory, said by 1996 the incidence of Bovine Spongiform Encephalopathy should be down to about 1,000 cases a year - about the same number of cases being reported each week at present. But he refused to predict when the disease would finally be eradicated from Britain.
The ministry warned that 1992 would show the highest number of reported BSE cases so far. Currently the disease is running at more than 3,000 cases a month and the incidence will continue to rise for several months yet.
The government expects it will have to pay pounds 40m in compensation to farmers for affected cattle this year. More than 70,000 cattle have been affected since the epidemic was first recognised in 1986.
Mr Wilesmith was speaking at a conference in Edinburgh on the implications of scrapie in sheep and BSE for other brain diseases, including ones affecting humans. But the conference was told there was no evidence to suggest people could acquire brain disease from eating or handling infected meat.
Mr Wilesmith said that the incidence of BSE among younger cattle was falling rapidly, following the ban introduced in July 1988 on incorporating cattle and sheep remains into the feed given to cattle and sheep. Only 291 cases of BSE had been identified in cattle born after the ban was introduced. All the affected cattle appeared to have been fed meat and bonemeal produced before the ban.
He said it was now clear that the source of the mad cow disease epidemic was meat and bonemeal contaminated with sheep scrapie produced in the years after 1981. Changes in the meat rendering industry's processes had allowed the scrapie agent to survive in the cattle feeds.
Infected cattle remains were then recycled back into the rendering industry's production lines, fuelling the epidemic. The recycling began before the first cases of BSE were recognised.
Mr Wilesmith also said that the conditions which had produced the BSE epidemic were unique to Britain. 'I think we may be on our own in terms of the epidemic,' he said. There were three crucial factors. The UK had a large number of sheep relative to its cattle population, there was scrapie present among the sheep, and Britain recycled ruminant protein to ruminants. No other European country had all three risk factors.
Other countries have had a few cases of BSE. Switzerland has had 17 and France five, but this might be due to imported, contaminated meat and bonemeal from Britain.
BSE, which is now affecting 1 per cent of the cattle population, was picked up when the incidence was only one in ten thousand. Some scientists have expressed worries that when the present scare is over and mad cow disease dies down, the spending cuts may reduce the capability of the country's research laboratories to meet the challenge of any future diseases which by definition could not be predicted in advance.
Scrapie, the brain disease which affects sheep, is to be made a notifiable disease in Britain next year, as a result of EC legislation. Farmers who wish to export sheep will first have to secure a certificate testifying that their flocks are free of the disease.
Some veterinary surgeons fear that this may drive the disease underground by inducing farmers to conceal cases of the disease in their sheep.Reuse content