Why was the Western blot used?
A. The OIG, in reviewing USDAs enhanced surveillance system, decided last week that USDA should retest with a second confirmatory test, which is called the Western blot. The OIG has yet to explain why they ordered this second test. The IHC test was used in November to confirm the original rapid screening test, however the IHC test came back negative and they deemed the animal negative. The Western blot test is the only other means of confirmatory testing authorized under the USDA protocol, which are consistent with the OIE standards for BSE surveillance. The OIG demanded that the Western blot test be run. Q. Is the Western blot more sensitive? A. The IHC and Western blot are considered to be equally specific; they simply use different means to test for the disease. The Western blot has the ability to test for a broader spectrum of abnormalities. In a few cases world wide, the tests have disagreed with each other primarily in cases where the Western blot detected abnormalities that are
