WASHINGTON, DC, June 24,
2005 (ENS): A second U.S. animal has tested positive for
mad cow disease, Agriculture Secretary Mike Johanns said today.
Effective immediately the U.S. Department of Agriculture is adding
a second diagnostic test to its protocol for determining whether
suspect cattle are infected with the fatal brain wasting disease.
The U.S. Department of Agriculture (USDA) has received final test
results from The Veterinary Laboratories Agency in Weybridge, England,
confirming that a sample from an animal that was blocked from the
food supply in November 2004 has tested positive for bovine spongiform
encephalopathy (BSE), commonly called mad cow disease.
The suspect animal was a downer cow, one unable to walk, so it
never entered the food chain, Johanns said.
It was one of the three suspect animals whose brain tissue had
been tested three times since November, using three different procedures.
Results were positive for one cow on one of the three tests. The
other tests were either inconclusive or negative for all three cows.
The tests performed at Weybridge confirmed BSE in the cow that
had tested positive in one U.S. test.
Johanns directed USDA scientists to work with international experts
"to thoughtfully develop a new protocol that includes performing
dual confirmatory tests in the event of another "inconclusive"
BSE screening test.
"We are currently testing nearly 1,000 animals per day as part
of our BSE enhanced surveillance program, more than 388,000 total
tests, and this is the first confirmed case resulting from our surveillance,"
Effective immediately, if another BSE rapid screening test results
in inconclusive findings, the USDA will run both an immunohistochemistry
(IHC) and Western blot confirmatory test. If results from either
confirmatory test are positive, the sample will be considered positive
for BSE, Johanns said.
Both tests are accepted by the OIE, the World Animal Health Organization.
"This confirmed case of BSE in no way impacts the safety of
our nation's food supply," said Johanns.
"I want to make sure we continue to give consumers every reason
to be confident in the health of our cattle herd," the secretary
said. "By adding the second confirmatory test, we boost that
confidence and bring our testing in line with the evolving worldwide
trend to use both IHC and Western blot together as confirmatory
tests for BSE."
"I am encouraged that our interlocking safeguards are working
exactly as intended. This animal was blocked from entering the food
supply because of the firewalls we have in place," he said.
"Americans have every reason to continue to be confident in
the safety of our beef."
Only one case of mad cow disease had been confirmed previously
in the United States, in a dairy cow in Washington State in December
2003. Since then, preliminary tests indicated the possibility of
the disease in three cows, but further testing had ruled out any
USDA has initiated an epidemiological investigation to determine
the animal's herd of origin. That investigation is not yet complete.
The animal was born before the United States instituted a ruminant-to-ruminant
feed ban in August 1997, which prevents the use of most mammalian
protein in cattle feed.
According to internationally accepted research, feed containing
meat-and-bone meal is the primary way BSE is transferred to the
The animal was selected for testing because, as a non-ambulatory
animal, it was considered to be at higher risk for BSE. An initial
screening test on the animal in November 2004 was inconclusive,
triggering USDA to conduct the internationally accepted confirmatory
IHC tests. Those test results were negative.
Earlier this month, USDA's Office of the Inspector General recommended
further testing of the seven-month-old sample using another internationally
recognized confirmatory test, the Western blot. Unlike the IHC,
the Western blot was reactive, prompting USDA to send samples from
the animal to the Weybridge laboratory for further analysis.
The laboratory in Weybridge, England, is recognized by the OIE
as a world reference laboratory for mad cow disease. Weybridge officials
this week conducted a combination of rapid, IHC and Western blot
testing on tissue samples from the animal in question. At the same
time these diagnostic tests were being run by Weybridge, USDA conducted
its own additional tests.
As a non-ambulatory, or "downer" animal, the cow was
prohibited from entering the human food supply, under an interim
final rule in effect since January 2004. Research has shown that
BSE is most likely to be found in older non-ambulatory cattle, animals
showing signs of central nervous system disorders, injured or emaciated
animals, and cattle that have died for unexplained reasons. USDA's
testing program targets these groups of animals for testing.
The system of human health protections includes the USDA ban on
specified risk materials, or SRM's, from the food supply. SRM's
are most likely to contain the BSE agent if it is present in an
Additional measures, such as a longstanding ban on importing cattle
and beef products from high-risk countries, a ruminant-to-ruminant
feed ban, U.S. slaughter practices, and aggressive surveillance
provide a series of interlocking safeguards to protect U.S. consumers
and animal health.
As the epidemiological investigation progresses, USDA pledged to
continue to communicate findings in "a timely and transparent
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