The United States may have uncovered a second case of mad cow disease, Agriculture Department officials said Thursday.
They stressed that no meat from the suspect cow would have entered the food chain, but otherwise provided few details and refused to say where the animal was found.
While the cattle industry has urged that such details not be released, it will be four to seven days before any confirmation is available, a delay that is likely to cause turmoil in the beef market.
Mad cow disease, or bovine spongiform encephalopathy, attacks an animal’s nervous system and is always fatal. People who eat BSE-contaminated meat can contract a related human affliction, known as variant Creutzfeldt-Jakob disease.
Suspicions about a new case of the disease in the United States came after two simultaneous test results could not rule out an infection.
“The inconclusive result does not mean we have found another case of BSE in this country,” said Andrea Morgan, associate deputy administrator of the USDA’s Animal and Plant Health Inspection Service.
State agriculture officials said the animal did not originate in Kansas, Montana, New Jersey, North Carolina, North Dakota or Wyoming. Officials in Washington state — where the first case was found — said they did not believe it was found there.
Barb Powers of the Colorado State University’s , which handles samples from numerous states, said she learned of the new results from news reports. Thus, the sample may not have come from Colorado, Hawaii, Illinois, Indiana, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, Utah, Washington or Wyoming.
Labs in six other states, including California and Texas, also test for mad cow. A California testing official could not comment on whether the sample originated there.
“It is important to note that this animal did not enter the food or feed chain,” Morgan said. “USDA remains confident in the safety of the U.S. beef supply.”
She reiterated the USDA's position that federal restrictions on high-risk material in the food supply remain the best safeguards against the disease.
New USDA testing procedures have raised the level of concern about the suspected case. Previously, a single initially positive result from a state lab was publicly disclosed and sent to the USDA's national lab in Ames, Iowa, for a final confirmation using a more accurate procedure. Now, at least two initial samples must be positive before the sample is sent to the national lab, which dramatically raises the chance that another case has been found.
"It's not just a confusion or an oops or a mistake," said Chris Waldrop of the Consumer Federation of America. "They're nailing it down before they send it off."
Initial testing uses a sensitive method known as Elisa, which sometimes detects proteins that do not prove to be infectious. The second-result requirement was added in August, USDA spokesman Jim Rogers said. While tests are conducted simultaneously, two or three samples from the same animal must be positive before being sent to Ames.
As to the number of samples in this case, "we're not saying, but you can imagine it's more than one," Rogers told MSNBC.com.
The department announced two possible cases in early July, both of which were later confirmed negative. But they initially unsettled the beef markets and Thursday's announcement set off another market upheaval. Shares of McDonald’s, Wendy’s, and other restaurant chains that feature hamburgers slumped, as did those of U.S. meat producers such as Tyson Foods, Inc.
Cattlemen maintain the first mad cow case significantly impacted their bottom line. Some meatpacking firms' revenues dropped off, though sales of red meat and prices are steady.
Some 113,000 animals have been tested under revised procedures that took effect June 1, with a goal of testing as many as 268,000 by the end of 2005, though officials will not set firm targets.
The testing plan addressed complaints that too few animals were being checked for the disease, though some consumer groups still maintain it falls short. The program focuses on higher-risk cattle; the current case is from such an animal, officials said.
In the only confirmed U.S. case of mad cow, a Canadian-born Holstein was found 11 months ago to have been infected. That case prompted Japan and dozens of other countries to ban U.S. beef, though Japan to accept young U.S. cattle again.
The disease usually manifests itself in older cows, though it has been found in cows as young as 20 months.
Administration officials are considering a national identification system to track livestock and poultry. Agriculture Secretary Ann Veneman, who recently resigned, endorsed such a system after the first case of mad cow, but little progress has since been made.
Such a system worries producers who want to keep their records confidential. They have proposed a voluntary industry-run system instead. Food-safety advocates believe a mandatory system is needed to trace the origins of diseased animals.
"When you have a positive, it's not the cow you found that you worry about," said Caroline Smith DeWaal of the Center for Science in the Public Interest. "It's the ones you didn't find that were exposed at the same time."
The Associated Press contributed to this report.