27 July 2001

Scrapie probably caused BSE

By Alistair Driver

THE drive to rid British sheep of scrapie has gained momentum after an independent government review controversially identified it as the probable cause of mad-cow disease.

The review was published last Thursday (July 19) – the same day the government launched a national scrapie eradication programme (see p35). Although the BSE Inquiry last year ruled out scrapie as the cause of mad-cow disease, the review concludes: "It is no longer possible to exclude an unmodified scrapie agent as the agent responsible for BSE."

The review acknowledges that the science regarding the origins of BSE is still uncertain. But it adds weight to the National Scrapie Plan to eradicate the disease in sheep. The possibility that the disease actually started in cattle and that environmental factors and toxic chemicals may have had a role is not ruled out. But in its explanation of BSEs origins in the 1970s and 1980s it suggests why scrapie could be to blame.

The UK had the largest sheep population in the EU between 1970 and 1985 and there are an estimated 5000-10,000 cases of scrapie each year. Although no scrapie strain with BSE characteristics has been found, research has been based on small numbers of sheep, it says. Changes in rendering processes and feeding meat and bonemeal to young calves increased the chances of a BSE agent in scrapie spreading among cattle, it claims.

The findings were attacked by the National Sheep Association. Chief executive John Thorley said: "They are a very long way from the truth. It is far more likely the disease started in cattle," he said. Mr Thorley said the review does, however, illustrate the need to eradicate scrapie. "There will always be scientific doubt so we need to make it clear we are free of scrapie," he said.

British Veterinary Association BSE spokesman Francis Anthony said it was bizarre that the original BSE Inquiry had ruled out scrapie.

"I think the scrapie theory is the only one that holds any water," he said, before adding: "We still do not know if scrapie affects humans or whether BSE affects sheep."

Peter Janion, a government advisor on BSE, agreed that the review illustrated the need to eliminate scrapie. But the findings were described as "dubious" by Stephen Dealler, a former government scientist who has worked on the origin of BSE since 1988. "They have just followed the initial MAFF nonsense about scrapie," he said.

Dr Dealler said there was too much uncertainty to single out scrapie as the cause of BSE. A more plausible explanation was the use of BSE-infected pituitary hormones in cattle in the 1970s and 1980s, he added. &#42