The USDA claims to have tested approximately 20,000 cows for the disease in 2002 and 2003, but has been unable to provide any documentation in support of this to UPI, which first requested the information in July.
In addition, former USDA veterinarians tell UPI they have long suspected the disease was in U.S herds and there are probably additional infected animals.
USDA Secretary Ann M. Veneman announced late Tuesday during a hastily scheduled news briefing that a cow slaughtered Dec. 9 on a farm in Mabton, Wash., had tested positive for mad cow disease. The farm has been quarantined but the meat from the animal may have already passed into the human food supply.
The slaughtered meat was sent for processing to Midway Meats in Washington and the USDA is currently trying to trace if the meat went for human consumption, Veneman said.
The fear is mad cow disease can infect humans and cause a brain-wasting condition known as variant Creutzfeldt-Jakob disease that is always fatal. More than 100 people contracted this disease in the United Kingdom after a widespread outbreak of mad cow disease in that country in the 1980s.
An outbreak of mad cow disease in the United States has the potential to dwarf the situation in the United Kingdom because the American beef industry is far larger and U.S. beef is exported to countries all over the globe.
"We're talking about billions of people" around the world who potentially have been exposed to U.S. beef, Lester Friedlander, a former USDA veterinarian who has been insisting mad cow is present in American herds for years, told UPI.
The USDA insisted the case is probably isolated and the US beef supply is safe. "I plan to serve beef for my Christmas dinner," Veneman said, "and we remain confident in the safety of our food supply."
Responded Friedlander: "She might as well kiss her (behind) goodbye, then."
Veneman went on to say she had confidence in the USDA surveillance system for detecting mad cow and protecting the public, noting the agency has tested more than 20,000 cattle for the disease this year.
This represents only a small percentage of the millions of cows in the U.S. herd, however, and experts say current procedures are unlikely to detect mad cow.
The Washington cow was tested because it was a so-called downer cow -- a cow unable to stand on its own -- which is one possible sign of mad cow disease. However, the United States sees approximately 200,000 of these per year or about 10 times as many animals as are tested for the disease.
USDA officials told UPI as recently as Dec. 17 the agency still is searching for documentation of its mad cow testing results from 2002 and 2003.
UPI initially requested the documents on July 10, and the agency sent a response letter dated July 24, saying it had launched a search for any documents pertaining to mad cow tests from 2002 and 2003.
"If any documents exist, they will be forwarded," USDA official Michael Marquis wrote in the letter.
Despite this and a 30-day limit under the Freedom of Information Act on responding to such a request, the USDA never sent any corresponding documents. The agency's FOI office also did not return several calls from UPI placed over a series of months.
Finally, UPI threatened legal action in early December if the agency did not respond.
In a Dec. 17 letter to UPI from USDA Freedom of Information Act Office Andrea E. Fowler, the agency wrote: "Your request has been forwarded to the (Animal and Plant Health Inspection Service) for processing and to search for the record responsive to your earlier request."
To date, the USDA has not said if any records exist or if they will be sent to UPI.
"It's always concerned me that they haven't used the same rapid testing technique that's used in Europe," where mad cow has been detected in several additional countries outside of the United Kingdom, Michael Schwochert, a retired USDA veterinarian in Ft. Morgan, Colo., told UPI.
"It was almost like they didn't want to find mad cow disease," Schwochert said.
He noted he had been informed that approximately six months ago a cow displaying symptoms suggestive of mad cow disease showed up at the X-cel slaughtering plant in Ft. Morgan.
Once cows are unloaded off the truck they are required to be inspected by USDA veterinarians. However, the cow was spotted by plant employees before USDA officials saw it and "it went back out on a special truck and they called the guys in the office and said don't say anything about this," Schwochert said.
Veneman said the Washington case "does not pose any kind of significant risk to the human food chain."
Friedlander called that assessment, "B.S." Referring to the USDA's failure to provide their testing documentation to UPI, he said, "The government doesn't have records to substantiate their testing so how do they know whether this is an isolated case." The agency also cannot provide any assurance that this animal did not get processed for human consumption, he said.
Schwochert agreed with that, saying the USDA's sparse testing means they cannot say with any confidence whether there are additional cases or not.
Both Schwochert and Friedlander said the report of a mad cow case would devastate the U.S. beef industry.
"It scares the hell out of me what it's going to do to the cattle industry," Schwochert said. "This could be catastrophic."
Only hours after Veneman's announcement, Japan -- the biggest importer of U.S. beef -- and South Korea both banned the importation of American meat.
The American Meat Institute, a trade group in Arlington, Va., representing the U.S. meat and poultry industry, maintained the U.S. beef supply is safe for human consumption.
"First and foremost, the U.S. beef supply is safe," AMI spokesman Dan Murphy told UPI. "We think its safe for U.S. consumers to eat."
This is because infectious prions, thought to be the causative agent of mad cow and vCJD, are not found in muscle tissue that comprises hamburgers and steaks, he said. They are generally located in brain and spinal cord tissue.
However, recent studies have suggested prions may occur, albeit in smaller numbers, in muscle tissue, and bits of brain and spinal cord tissue have been detected in hamburger meat.
Other protective measures have also been put in place that should protect consumers, Murphy said.
Mad cow disease is thought to be spread by feeding infected cow tissue back to cattle -- a practice that was common in the United Kingdom and is thought to have contributed to their widespread outbreak. The practice has been banned in the United States by the Food and Drug Administration since 1997, which should help ensure this is "an isolated case," Murphy said.
A report from the General Accounting Office issued just last year, however, found some ranchers in the United States still violate the feed ban and do feed cow tissue to cattle.
The GAO concluded: "While (mad cow disease) has not been found in the United States, federal actions do not sufficiently ensure that all (mad cow)-infected animals or products are kept out or that if (mad cow) were found, it would be detected promptly and not spread to other cattle through animal feed or enter the human food supply."
Steve Mitchell is UPI's medical correspondent. E-mail firstname.lastname@example.org