Tests have confirmed another case of mad cow disease in the United States since the first case was reported in December 2003, the US Agriculture Department announced Friday.

The second case in a beef cow was confirmed by an internationally recognized laboratory in Weybridge, England, Agriculture Secretary Mike Johanns said. The new tests were ordered after US tests produced conflicting results. The department also conducted more tests at its lab in Ames, Iowa.

Johanns said human health was not at risk.

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

The new case was one of the three suspected animals that had been previously tested negative for mad cow disease. They were tested again two weeks ago with a different technology at the request of the USDA's Inspector General who was reviewing the department's mad cow testing program. The results showed one animal tested positive.

The first US confirmed case of mad cow disease was reported in December 2003 in a Washington state dairy cow, which was imported from Canada.

People eating animal meat products contaminated with mad cow disease, or bovine spongiform encephalopathy (BSE), can develop a human variant of the fatal brain-wasting disease, called Creutzfeldt-Jakob disease.

The brain disorder has killed more than 150 people, mostly in Britain, where an outbreak was reported in the 1990s.

Source: Xinhua