Scientists at the Veterinary Laboratories Agency in Weybridge, England, told the U.S. Agriculture Department Thursday that they concur with the reading of tests on the stricken Holstein cow that led U.S. officials to conclude the animal had the brain-wasting disease, U.S. officials said.
"We are considering this confirmation," said USDA spokeswoman Alisa Harrison, adding that the English lab still will conduct its own test using another sample from the cow's brain. Final test results on the cow from Washington state were expected by the end of the week, she said.
Professor Steven Edwards, chief of the British lab, said those results already have been given to USDA. But Edwards refused to disclose whether the tests show that the animal had mad cow disease, or bovine spongiform encephalopathy.
The 4,000-head Washington state dairy herd the lone infected cow was part of remains under quarantine. It is believed that the cow contracted the disease elsewhere while it was being raised with a different herd and was infected after eating feed tainted with diseased cattle renderings, reports CBS News Correspondent Jerry Bowen.
"The animal in question did have some identification on her which should hopefully help us in doing the trace back," said Dr. Ron De Haven, the USDA's chief veterinarian. "If everything goes perfectly, we should be able to trace back to the birth herd within a day or two."
The threat to humans is considered exceedingly small since the cow's diseased tissue is not believed to have been processed with its meat into ground beef.
But the slaughterhouse involved is recalling 10,000 pounds of beef the cow was part of. And grocery chains in Washington, Oregon and Idaho cleared shelves of beef from a supplier who may have butchered the affected animal.
Critics say U.S. agriculture officials are failing consumers.
"The fact that they don't know where the cow's eventually wound up is a concern for all of us. The technology exists for them to know where the cow went and why they are not telling the public tells me they have no idea," said food safety attorney Bill Marler.
Meanwhile, its nervous time for consumers and beef producers.
"Obviously consumer confidence is paramount in the whole issue. We want to get this thing resolved as quickly as possible," said Richard Wortham of the Texas Beef Council.
But until investigators learn where the disease started they can't be sure just how a big problem they're dealing with.
Meanwhile, the United Arab Emirates and China, which in 2002 imported $532 million of meat products, became the latest nations to suspend U.S. beef imports.
Japan, the world's biggest importer of U.S. beef on a value basis, imposed an immediate ban after the U.S. announcement late Tuesday, and Mexico, the top importer by tonnage, quickly followed on Wednesday.
South Korea, Hong Kong, Singapore, Malaysia, Taiwan, Australia and Thailand, Paraguay, Chile, Brazil, Colombia, Russia, Peru, Canada, South Africa, and Trinidad and Tobago all halted imports.
In the first direct blow to the $40 billion beef sector, transactions on the Chicago Mercantile Exchange were frozen Wednesday after live cattle prices fell by the maximum permissible margin.
Shares of the world's biggest hamburger chain, McDonald's, tumbled $1.32 or 5.22 percent to finish at 23.96 dollars.
Its rival, Wendy's, slipped $1.87 or 4.72 percent to $37.79 even as it told customers that the beef in its burgers was safe.
Amid all the chaos, residents in the tiny town of Mabton, Wash., the location of the cow linked to the disease, tried to find humor in the tense situation.
Linda Chester of the Silver Dollar Inn told CBS News Correspondent Stephan Kaufman they may serve a "mad cow burger."
"We do a lot of roast beef specials," she said. "We're going to stick with our beef."