Scrapie-prone sheep ‘a risk that failed’

Press, 19 August 1978, Page 3

Scrapie-prone sheep ‘a risk that failed’

The imports of exotic sheep in 1972 were a "calculated risk that had not come off,” said Dr J. T. Stamp, the authority on scrapie, yesterday, before he left Christchurch for Australia on his way back to Britain.

The sheep were imported from Britain in 1972, to improve New Zealand’s sheep flocks. But after the discovery of scrapie in these imported sheep on Mana Island in 1976, and again

this year, the project has had to be abandoned. Dr Stamp was asked to come to New Zealand to advise the Government about the fate of sheep on Crater block, near Rotorua, some of which originally were moved from Mana. On Mana there had been two definite cases of scrapie and there might have been several others, said Dr Stamp. He told a big audience at a seminar at Lincoln College — attended by people from as far away as Southland — that since he had been in New Zealand he had seen lesions characteristic of scrapie in sheep brain material. Had the animals on Crater block not also been destroyed, it was a safe assumption that the disease would have recurred there. Advice to New Zealand authorities before 1972 had been that it would be better not to import sheep from Britain. However, if it were found necessary to do so for genetic reasons

then safeguards should be taken such as the strict quarantine that had been attempted, he said.

Canada had been importing North County Cheviots from Britain, under ~<e same sort of conditions as New Zealand, without getting the disease. However, C j New Zealand imports were a greater risk because they mainly were of sheep exotic to Britain, and came from properties through which there had been a considerable flow of stock.

Discussing research on scrapie, Dr Stamp said research on mice that were "resistant” to it had shown that they were not resistant or immune in the normal way. The agent that caused scrapie was present all the time but the mouse died of old age before clinical symptoms showed up. It was not known whether this applied in sheep, too, but it was a frightening thought. If it were the case, it was to be hoped that they were not excreting the disease spores all the time.