US herd quarantined over BSE fear

The diseased cow is thought to have come from Canada

A third herd of cattle has been placed under quarantine in Washington state following the discovery of the US's first case of mad cow disease.

The US Agriculture Department's chief veterinarian Dr Ron DeHaven said at least some of the cows from the herds would have to be slaughtered.

He said 11 of the 81 cows believed to have been shipped from Canada with the infected animal had been accounted for.

At least 26 countries have placed restrictions on the import of US beef.

DNA tests are being carried out to prove conclusively whether the infected cow - slaughtered on 9 December - came from a herd in Alberta, Canada.

In the meantime, investigators are tracing herdmates of the infected cow, which crossed the border from Canada with 80 other cows in 2001.

"We now have 11 of them accounted for," said Mr DeHaven.

The most likely source of infection is thought to be contaminated feed given to the animal as a calf.

'Sacrificed'

The latest herd to be put under quarantine is at a dairy farm in Mattawa, Washington.

BOVINE SPONGIFORM ENCEPHALOPATHY First surfaced mid-1980s Can pass to humans through infected beef products Human form of disease called vCJD vCJD has killed 137 people, mainly in the UK Agriculture Dept statement Ban on US beef

Mr DeHaven said it was likely that some of the quarantined animals would have to be killed.

"It would be safe to assume... some or all those animals will need to be sacrificed," he said.

A decision on the first cows to be killed will be made soon. The diseased Holstein was slaughtered on 9 December.

The US Department of Agriculture said earlier in the week it would appoint a global panel of scientists to review its response to the country's first case of the disease.

US experts have predicted that news of the BSE case will cost the US cattle industry billions of dollars.