USDA announced this evening it is sending a brain sample to the Bovine Spongiform Encephalopathy World Reference Laboratory in Weybridge, England, from one of the three cows that tested inconclusive and was later confirmed negative in 2004. A separate test was requested by the USDAâ€™s Office of Inspector General on all three samples, and one of the tests returned positive.
Multiple tests can identify BSE. One commonly used method is the internationally recognized immunohistochemistry (IHC) test, the test initially run. All three inconclusive samples tested negative using IHC. The OIE-recognized SAF immunoblot test, often referred to as the Western blot test, was run this week on all three animals. Of the three samples, two were negative, but the third came back reactive.
"Because of the conflicting results on the IHC and Western blot tests, a sample from this animal will be sent to the OIE-recognized reference laboratory for BSE in Weybridge, England. USDA will also be conducting further testing, which will take several days to complete," says Dr. John Clifford, Animal and Plant Health Inspection Service Chief Veterinarian.
Clifford explains that the animal in question was a non-ambulatory (downer) animal and as such was banned from the food supply. It was processed at a facility that handles only animals unsuitable for human consumption, and the carcass was incinerated. In a telephone conference, Clifford explained that the animal was an aged beef animal and there is no indication that was imported. The initial test results for the animal were released November 15, 2004.
"USDA's enhanced surveillance program is designed to provide information about the level of prevalence of BSE in the United States. Since the inception of this program, we have fully anticipated the possibility that additional cases of BSE would be found," Clifford adds. "And, in fact, we are extremely gratified that to date, more than 375,000 animals have been tested for the disease and, with the exception of the conflicting results we have received on this one animal, all have ultimately proven to be negative for the disease."
Results are expected over the next several days. A statement from National Cattlemen's Beef Association President Jim McAdams says, "NCBA supports getting a clear and definitive answer on this sample as quickly as possible and requests USDA Secretary Johanns take whatever steps are necessary to do so."
Clifford says USDA will continue to evaluate the risk mitigation measures after final conclusions of the test. "We are committed to ensuring that we have the right protocols in place-ones that are solidly grounded in science and consistently followed," he says. "After we receive additional test results on this animal, we will determine what further steps need to be taken and what changes, if any, are warranted in our surveillance program."