Third U.S. case of mad cow disease

According to the U.S. Department of Agriculture routine tests have revealed a third U.S. case of mad cow disease.

The officials are waiting for the results of more detailed testing at government laboratories in Iowa, to confirm the presence of mad cow disease.

The suspect animal was found when a brain sample yielded an "inconclusive" result during a rapid-screening test.

The department has not said where the cow was from.

The suspected case is a major setback for officials as it follows months of work in trying to reopen beef trade with Japan and South Korea.

According to John Clifford, the USDA's chief veterinarian, there is no risk to public health as the carcass did not enter the food chain.

The American Meat Institute, has also said most inconclusive test results have later proved to be negative for the disease.

Meanwhile Washington is working to allay concerns from overseas trading partners.

Japan had been one of the top customers of American beef before the first U.S. case of mad cow disease prompted a ban.

Japan stopped U.S. beef shipments in January after finding veal cuts with backbone, cuts that are eaten in the U.S. but not in Asia.

Agriculture Secretary Mike Johanns has met his Japanese counterpart and promised to answer Japan's questions about how the veal was shipped contrary to the rules governing U.S.-Japan beef sales.

In general since the disease was first discovered in the United States in December2003, the American market has been unaffected and Americans have continued to buy and eat beef.

Japan and South Korea, have been hesitant to resume trade despite U.S. assurances that its beef is safe.

South Korea was due to reopen its borders in April to U.S. beef, banned since December 2003, when the first U.S. case was reported in a dairy cow in Washington state.

Experts say the new suspected case will make it more difficult to convince both countries to lift the bans.

Whether the animal was infected affects issues other than trade.

The decision by the department to scale back its higher level of testing for mad cow disease has been in the air for some time.

Testing for the disease was increased from about 55 to 1,000 daily after the first case of mad cow disease in 2003.

To date 644,603 of the nation's estimated 95 million head of cattle have been checked under this enhanced level of testing.

Mad cow disease is the common name for bovine spongiform encephalopathy, or BSE.

In humans, eating meat products contaminated with BSE has been linked to more than 150 deaths, mostly in Britain, from variant Creutzfeldt-Jakob Disease, a rare and fatal nerve disease.

No human is known to have contracted the disease in the United States.

Experts believe mad cow disease is spread through contaminated cattle feed.

The two major U.S. safeguards against mad cow disease are a 1997 ban on using cattle parts in cattle feed and a requirement for meatpackers to remove from older cattle the brains, spinal cords and other nervous tissue most at risk of carrying the infective agent.

Both previous U.S. cases of mad cow disease, the Canadian-born dairy cow in Washington state and a crossbreed beef cow born in Texas in November 2004, were found in animals born before the feed ban.

Hong Kong officials have also suspended imports from a U.S. beef processing company following the discovery that its products contained bones prohibited under regulations aimed at protecting against mad cow disease.

Hong Kong had partially lifted a two-year ban on U.S. beef imports in December, and only boneless beef from cattle less than 30 months old, and without the animal's brain, spinal cord or other parts considered high risk for mad cow disease, are allowed into the territory.