John Clifford, deputy administrator for USDA's Animal and Plant Health Inspection Service announced today that the confirmatory tests performed on a suspect animal are negative for bovine spongiform encephalopathy. This actually follows two inconclusive results from the rapid-screening test.
Testing at the USDA National Veterinary Services Laboratories in Ames, Iowa, was conducted using the immunohistochemistry test, an internationally-recognized gold standard test for BSE. It resulted in a negative result on Nov. 22. However, because the Nov. 18 screening test results were reactive in both the first and second screens, NVSL scientists recommended that the IHC test be run a second time. On Nov. 23 they reported the second IHC test was negative.
"Negative results from both IHC tests makes us confident that the animal in question is indeed negative for BSE," says Clifford.
The Nov. 18 sample is the first that has tested inconclusive under an APHIS protocol announced in August that calls for public reporting of screening results only after two reactive screens.
APHIS began an enhanced surveillance program on June 1, and to date has tested more than 121,000 samples for BSE. Screening tests are designed to be extremely sensitive and false positives are not unexpected. APHIS has reported three inconclusive results, including the Nov. 18 sample and all have tested negative on confirmatory testing."