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Results from retesting of brain tissue of a U.S. animal
confirms that it suffered from bovine spongiform encephalopathy,
the first ever native-born case of BSE to be discovered
in the United States. USDA indicated that the beef animal
was born before the September 1997 ban on ruminant-to-ruminant
feed was put into effect, and was over 8 years of age.
Agriculture Secretary Mike Johanns announced the discovery
this afternoon in Washington, and also indicated that after
the controversy over BSE test protocols, USDA will develop
new protocols that subject samples that return conflicting
or uncertain test results for BSE to both the immunohistochemistry
test USDA has traditionally used, as well as the Western
blot, which most BSE authorities consider the most conclusive
test method.
The samples returned two positive tests last October when
the Bio-Rad rapid test was applied, then returned negative
results when the IHC test was applied. A surprising retesting
of the tissue using the Western blot test at USDA's Ames,
Iowa, laboratory two weeks ago resulted in what USDA called
a "weak positive," at which point it was sent to the OIE's
BSE laboratory in Weybridge, England for confirmation.
Johanns conceded that USDA's protocol, which prefers IHC
to Western blot, might be out of date, and that a new protocol
will be developed that examines samples with both tests
simultaneously.
Johanns also acknowledged that body parts from five animals
were stored together during the test process last fall,
a failure of the sampling and segregation procedures that
APHIS developed. Freezing of samples will be discontinued
immediately, Johanns said.
USDA scientists will meet with international authorities
to develop a comprehensive protocol for all detection, handling
and testing of suspected BSE cases.
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