Breaking News Western Blot Test Finds BSE-Suspect Cow Positive USDA confirmed this afternoon that a non-ambulatory Santa Gertrudis cow in Alabama has been confirmed as positive for BSE. In addressing reporters, Chief Veterinary Medical Officer John Clifford said the animal, which the local veterinarian gauged by dentition to be more than 10 years old, was confirmed as positive for BSE using the Western blot test.
The Western Blot Test is one of two confirmatory tests used by USDA in the further testing of animal tissues that result as "inconclusive" under rapid testing. The other confirmatory test used by USDA is the immunohistochemistry test (IHC test). If either confirmatory test results in a positive, that animal is considered as positive fore BSE, Clifford said.
Clifford said the BSE-positive animal is thought to have resided on the Alabama farm for less than one year.
"The samples were taken from a non-ambulatory animal on a farm in Alabama. A local private veterinarian euthanized and sampled the animal and sent the samples for further testing, which was conducted at one of our contract diagnostic laboratories at the University of Georgia. The animal was buried on the farm and it did not enter the animal or human food chains," Clifford said.
He added that USDA's Animal and Plant Health Inspection Service (APHIS) is now working with Alabama animal health officials to conduct an epidemiological investigation to gather any further information we can on the herd of origin of this animal.
"We will be working to locate animals from this cow's birth cohort (animals born in the same herd within one year of the affected animal) and any offspring. We will also work with Food and Drug Administration officials to determine any feed history that may be relevant to the investigation. Experience worldwide has shown us that it is highly unusual to find BSE in more than one animal in a herd or in an affected animal's offspring. Nevertheless, all animals of interest will be tested for BSE.
"Under USDA testing protocols, surveillance samples are sent to contract laboratories for screening tests. If the sample is found to be inconclusive on the screening test, it is then shipped to our National Veterinary Services Laboratories (NVSL) in Ames , Iowa , for an additional rapid test and two confirmatory tests: the IHC test, which is conducted by APHIS scientists, and the Western blot test, which is conducted by scientists with USDA's Agricultural Research Service. USDA considers an animal positive for BSE if either of the two confirmatory tests returns a positive result.
"In this instance, the inconclusive result from the contract lab in Georgia was confirmed through a second rapid test at NVSL. Now, the Western blot test has returned a positive result, and that is sufficient for us to confirm this animal to be positive for BSE, which is why we are making this announcement today. The IHC results are still pending and we will release those results as soon as they are available, which we expect to be later this week.
"I want to emphasize that human and animal health in the United States are protected by a system of interlocking safeguards, and that we remain very confident in the safety of U.S. beef. Again, this animal did not enter the human food or animal feed chains.
"While epidemiological work to determine the animal's precise age is just getting underway and is ongoing, the attending veterinarian has indicated that, based on dentition, it was an older animal, quite possibly upwards of 10 years of age. This would indicate that this animal would have been born prior to the implementation of the Food and Drug Administration's 1997 feed ban. Older animals are more likely to have been exposed to contaminated feed circulating before the FDA's 1997 ban on ruminant-to-ruminant feeding practices, which scientific research has indicated is the most likely route for BSE transmission."
Clifford said the animal's country of origin is not yet known but USDA will work to complete its investigation "as quickly as we can."
He added that he doesn't expect the positive BSE result -- the third in the U.S. since December 2003 -- to impact the current negotiations with Japan for reopening of that market to U.S. beef.
Of similar interest is South Korea, which is in the final steps of reopening its market to U.S. beef in early April. That country earlier stated that it would consider re-imposing its ban on U.S. beef if another positive animal were to be found in the U.S. For more info, visit: www.usda.gov/wps/portal/usdahome. -- Joe Roybal