Jun. 24, 2005 - Tests have confirmed mad cow disease in a U.S. cow previously cleared of having the brain wasting illness, the Agriculture Department said Friday. It is the second case of mad cow disease in the United States.

An internationally recognized laboratory in Weybridge, England, confirmed the case of mad cow disease after U.S. tests produced conflicting results, Agriculture Secretary Mike Johanns said.

Human health was not at risk, Johanns said. The animal was a "downer," meaning it was unable to walk. Such animals are banned from the food supply.

New tests were ordered two weeks ago. Those results came back positive, leading officials to seek confirmation from the Weybridge lab. The department also performed more tests at its lab in Ames, Iowa.

The first case confirmed in the U.S. was in December 2003, a dairy cow imported from Canada.

"I am encouraged that our interlocking safeguards are working exactly as intended," Johanns said.

"This animal was blocked from entering the food supply because of the firewalls we have in place. Americans have every reason to continue to be confident in the safety of our beef," he said.