Herd containing calf of BSE-infected cow to be destroyed

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Jan 6, 2004 (CIDRAP News) – A herd of 450 bull calves that includes the offspring of the nation's first cow known to have bovine spongiform encephalopathy (BSE) will be euthanized as a precaution against the disease, the US Department of Agriculture (USDA) announced yesterday.

Because the calf of the BSE-infected cow cannot be certainly identified, the whole herd will be sacrificed for safety's sake, the USDA said in a news release. "USDA stresses again that BSE is not spread from cow to cow and that there is a low risk of transmission of BSE from heifer to calf," the statement said. Also, the calves are too young to have identifiable BSE, which usually has an incubation period of 4 to 5 years, officials said.

"No products from any of the euthanized animals will enter the human food chain, nor will products be rendered," the USDA said.

The bull calves at Sunnyside, Wash., apparently will be the first cattle to be sacrificed in response to the BSE case identified last month. The calves will be taken to a currently unused slaughter facility sometime this week, with the timing dependent on the weather, the USDA said. Officials didn't disclose the location of the facility.

The BSE case was identified Dec 22 in a Holstein cow from a herd at Mabton, Wash., near Yakima. Because the cow couldn't walk when brought to a slaughter plant Dec 9, its carcass was tested for BSE as part of routine surveillance. Samples tested positive at a USDA lab, and the tests were confirmed Dec 25 by a reference lab in Britain. But because inspectors thought the cow had had a birthing injury and wasn't sick, they released the carcass for processing before the test results came back. Meat from the cow and others slaughtered the same day was subsequently recalled. High-risk tissues—the brain, spinal cord, and distal ileum—were removed from the carcass at the time of slaughter, according to the USDA.

At a news briefing yesterday, USDA officials said the bull calves will not be tested for BSE because the infectious prion protein associated with BSE typically doesn't show up until an infected animal is at least 30 months old. "There would be no purpose in testing all of these animals, because even in the unlikely event that there had been maternal transmission to this single bull calf, the calf would not test positive at this point in time," said Ron DeHaven, the USDA's chief veterinary officer.

However, DeHaven said blood samples will be collected from a "subgroup" of the calves in case they are needed for DNA or other testing in the future.

Also because of the very low likelihood of BSE, the calf carcasses will not be incinerated or otherwise specially processed to destroy infectious prions, DeHaven said. He said that would be done if the animals were older, but the young age of the calves precludes any need for "extreme measures" such as incineration or use of an alkaline digester. He didn't disclose how the carcasses will be disposed of.

DeHaven also said the USDA will pay the owner the fair market value of the calves before they are sacrificed. The money will come from a USDA indemnity program.

In other comments yesterday, the USDA said investigators have determined that meat subject to the BSE-related recall went to Washington, Oregon, California, Nevada, Idaho, and Montana. Contrary to previous reports, none of the meat went to Alaska, Hawaii, or Guam.

The USDA has contacted all the businesses that may have received meat subject to the recall, and all have confirmed securing any remaining product and notifying customers of the recall, the agency said.

The BSE-infected cow is believed to have come from a farm in Alberta, according to previous USDA reports. The cow was one of a herd of 81 that was imported into the United States from Canada in September 2001. Nine other cows from the imported herd are now part of the Mabton, Wash., herd that included the sick cow, and one is in a dairy herd at Mattawa, Wash. Yesterday officials said they are still trying to trace the other 70 animals from the imported herd. The cows are being sought because they might have been exposed to BSE if they shared the same feed source when young, according to the USDA.

Yesterday marked the end of a public comment period on a USDA proposal to reopen the US border to live Canadian cattle for the first time since the announcement of Canada's single case of BSE last May. At yesterday's briefing, DeHaven said the agency would not take any further action on the proposal until the current BSE epidemiologic investigation is finished. He said USDA has not decided what to do on the issue.

The proposal is to allow the importation of cattle that are younger than 30 months and scheduled for slaughter before they reach that age. Currently the United States allows the importation of boneless beef from Canadian cattle up to 30 months old and veal from calves up to 36 weeks old.

In other recent developments, the USDA announced last week the probable members of an international expert panel that will review the US response to the BSE case and make recommendations. The team will be led by Dr. Ulrich Kihm, former chief veterinary officer of Switzerland. USDA said it has tentative commitments from Will Hueston, director of the University of Minnesota Center for Animal Health and Food Safety; Dagmar Heim, chief of BSE control for the Swiss Federal Veterinary Office; and Stuart McDiarmid, a BSE expert with the New Zealand government. The same four experts reviewed Canada's response to its BSE case last summer.

See also:

CIDRAP News story on the USDA proposal to reopen the border to live Canadian cattle

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