Domestic Cattle Untainted by British Imports, U.S. Says

About 500 head of British beef cattle were imported to the United States for breeding during the 1980s, The Times has learned, but the U.S. Department of Agriculture nevertheless reaffirms that “mad cow disease” has not been detected in the U.S.

There is no evidence that any of the 113 imported animals still alive carry bovine spongiform encephalopathy (BSE), which has been linked to the onset of Creutzfeldt-Jakob disease in humans in Britain. The cattle industry there has been under siege since a report linked 10 cases of the fatal brain disorder to individuals who may have consumed contaminated beef.

The British-born animals are scattered throughout the United States. The majority are located in Alabama, Texas, New York and Vermont and have been cross-bred with domestic cows. There is no way of knowing whether those animals carry the disease, because only post-slaughter laboratory examinations can identify it.

USDA veterinarians inspect the known remaining British cattle every six months and have found “no indication that they are infected with BSE,” an agency spokeswoman said.

No quarantine is planned.

Between 1981 and 1989, there were 499 head of cattle imported from Britain. Of that total, 343 are known to be dead, eight have been exported to Mexico and Canada, and 113 are still alive. The status of the remaining 35 animals is unknown, according to the USDA.

The 343 cattle known to be dead were slaughtered for their meat, which was most likely sold to the public in the form of ground beef.

Beef industry representatives and federal officials insist that there have been no cases of “mad cow disease” in this country.

The disease is thought to remain dormant in infected animals for as long as eight years before manifesting itself in erratic behavior, such as seizures.

Further complicating the issue is that scientists do not know how the disease is transmitted from animal to animal. Nor is it known conclusively that consumption of meat from BSE-infected cattle can cause Creutzfeldt-Jakob disease in humans.

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“Over the next, short period of time, the federal government will take a more vigorous response [to BSE],” said Morris E. Potter, assistant director for food-borne disease with the Centers for Disease Control and Prevention in Atlanta. “These 10 cases [in Britain] alarmed people. However, we certainly don’t want to set international or national health policy on a small number of deaths.”

British health officials first detected BSE in 1986. But a U.S. ban on animals from Britain did not go into effect until three years later.

There are an estimated 200 to 250 cases of Creutzfeldt-Jakob disease in the U.S. every year--more than triple the number in Britain, according to the CDC. One theory about the cause of the disease suggests some association with tissue or organ transplants.