The threat of mad cow's disease continues to vex health inspectors, tilt the beef trade industry and strain international trade relations with the Far East.

The tension was heightened in recent days when the United States Agriculture Department announced that a second case of bovine spongiform encephalopathy, or mad cow's disease, was confirmed after two conflicting test results.

USDA Secretary Mike Johanns said the third conclusive test was conducted at a laboratory in Weybridge, England.

Because the cow was unable to walk (referred to as a “downer”) it was never mainstreamed into the general food supply. Thus, Johanns observed, human health was never in jeopardy.

“I am encouraged that our interlocking safeguards are working exactly as intended,” Johanns said at a news conference. “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.”