USDA announced that an "older animal" on an Alabama farm tested positive for BSE. The western blot test conducted at USDA laboratories in Ames, Iowa, confirmed the positive results of rapid screening tests announced late Friday, March 10.
A local veterinarian euthanized and collected brain tissue from the cow for testing. The animal was buried on the farm and did not enter the human food or animal feed supplies.
Epidemiological work to determine the animal's precise age is ongoing, but the attending veterinarian indicated the cow possibly was upwards of 10 years of age, based on dentition. This would mean the animal was born prior to implementation of the 1997 Food and Drug Administration (FDA) ban on feeding ruminant by-products to cattle. Scientific research suggests ruminant-to-ruminant feeding is the most likely route of transmission for BSE.
Under USDA testing protocol, surveillance samples are sent to contract laboratories for rapid screening tests. If the sample is inconclusive on the rapid screening, it is sent to the USDA lab in Ames for an additional rapid test and two confirmatory tests. USDA considers an animal positive for BSE if either of the two confirmatory tests is positive. In this case, although the western blot was positive, results from the immunohistochemistry (IHC) test is pending. USDA Chief Veterinary Officer John Clifford said the IHC results will be released when available.
"This case shows, again, that the system works," said KLA President Ron Estes, a beef producer from Atchison. "Not only is USDA conducting surveillance on cattle at the highest risk for the disease, private veterinarians are watching for suspect animals as well."
USDA is working to gather further information on the animal's herd of origin. The agency also will be working with FDA officials to determine any feed history that might be relevant to the investigation. Clifford said all animals of interest would be tested for BSE.
Spokespersons are stressing any tissues considered at risk for carrying the BSE agent, primarily brain and spinal cord from older cattle, are removed at the processing plant and excluded from the human food supply. Scientific research has shown the BSE agent is not found in whole muscle cuts, such as steaks and roasts, or ground beef.