Mad Cow Testing Procedures in Spotlight

Reuters Limited

Cows feed at the Washington state dairy where a single case of mad cow disease has been confirmed.

The first confirmed case of mad cow disease in the United States raises questions about testing procedures for detecting the disease. Current U.S. policy is to test cows that show signs of trouble. Other countries -- such as Japan -- test every cow on the way to slaughter.

British scientists have confirmed that a cow from a farm near Yakima, Wash., is the first U.S. case of the fatal disease. The farm where the Holstein was kept has been quarantined and investigators are testing other animals there.

Earlier this year, a single contaminated cow was found in Canada, but investigators are still unsure how that animal became infected.

U.S. Agriculture Secretary Ann Veneman said the U.S. food supply was safe, and the risk to Americans' health was extremely low. Despite Veneman's assurance, more than a dozen nations, including top buyers of U.S. beef -- Japan, Mexico and South Korea -- have halted imports.

The infectious agent that causes mad cow disease, also known as BSE (bovine spongiform encephalopathy), can lead to a fatal disease in people. Research suggests humans contract a form of the disease, known as variant Creutzfeldt-Jakob, by eating beef products contaminated with BSE. Cows can get the disease when they're fed ground-up carcasses of cows with BSE. The U.S. government bans feeding animal parts to animals.