US animal tests positive for mad cow disease

WASHINGTON - In what could be the second US case of mad cow disease, an older beef animal tested positive for the deadly ailment but will undergo another round of tests at a British laboratory to confirm the results, Agriculture Secretary Mike Johanns said today.


The only US confirmed case of mad cow disease, or bovine spongiform encephalopathy (BSE), was found in December 2003 in a Washington state dairy cow. That discovery halted billions of dollars worth of American beef exports and raised questions about the safety of the US food supply.


Johanns said the new suspected case involved an older beef animal which was chosen for testing because it was a "downer" animal that could not walk when it arrived at the slaughterhouse. The animal's carcass never entered the human food or livestock feed supply, he said.


"This animal was a downer animal and did not get into the food or feed chain. There just is no risk whatsoever," Johanns told reporters in a hastily called news conference.


The government refused to disclose any information about the suspect animal's origin or where it was slaughtered. "It was getting up in age. It was a beef breed," said John Clifford, chief veterinarian for the Animal and Plant Health Inspection Service.


It is not unusual to have conflicting test results for BSE, cattle experts said.


The USDA said the suspect animal had tested positive for BSE in a rapid, preliminary test in November. When it was retested with a more sophisticated technology, the animal was found free of the disease.


But USDA's Inspector General earlier this week asked department scientists to retest the suspect animal, and two others, using yet a third kind of technology known as the "western blot" test. That test showed the beef animal was infected with the brain-wasting ailment, Johanns said.


USDA officials said they would send the animal's brain tissue to an internationally known laboratory in Weybridge, England for a final, confirmatory test.


"We have not confirmed a case of BSE in the United States at this time," said Clifford. "It's going to require additional testing to determine if this is BSE or not." Discovery of the suspect animal comes at a time when USDA officials have pressed Japan and South Korea to resume purchases of American beef. Both nations were major buyers of US beef until they suspended purchases in December 2003.


"I don't believe this has any impact on our international trading partners," Johanns said.


The United States has asked Japan to allow imports of American beef from cattle under 20 months of age. Scientists believe that younger animals pose less risk of the disease because it takes several years to incubate within an animal's nervous system.


At the same time, the USDA is involved in a lawsuit to reopen the US border to imports of cattle from Canada, which has confirmed three domestic cases of mad cow disease.


On Thursday, Johanns held a public meeting in Minnesota to make a public case for reopening the border to Canadian animals, which once accounted for about 1 million cattle slaughtered in the United States each year.


US meat industry officials say they are being forced to close plants and lay off workers because they cannot obtain enough cattle to keep the plants operating efficiently.


The National Cattlemen's Beef Association said it was not unusual to have conflicting test results for BSE.


"Multiple tests can identify BSE. One commonly used method is the internationally recognized immunohistochemistry test. Another test commonly used is the Western Blot test," Jim McAdams, president of the cattle group, said in a statement. "These two types of tests have returned conflicting results on this sample."


- REUTERS