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June 17, 2005, 12:25PM
Feds skipped key mad cow disease test in 2004 case
USDA changes its protocols after animal initially had been cleared
By DAVID IVANOVICH
Copyright 2005 Houston Chronicle Washington Bureau
WASHINGTON - Confronted with a possible case of mad cow disease last
year, the U.S. Agriculture Department failed to perform all of the same
rigorous tests it had used to confirm an incident of the brain-wasting
ailment back in 2003.
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Federal regulators skipped a key test last November that is routinely
used elsewhere by experts who say it is, under certain circumstances,
more effective for detecting the dread disease.
Relying on a single kind of test to verify the results of an initial
screening, USDA officials declared the cow - reportedly from Texas
- free of the disease.
That was a decision they have come to rue.
Seven months later, they had to acknowledge the animal may have been
infected after all.
That troubling reversal sent cattle prices falling this week and
sparked new questions about the USDA's ability to protect the public
while at the same time trying to promote U.S. agricultural interests.
"They don't go the extra mile," argued Craig Culp, a spokesman for the
Center for cooking.net">food Safety in Washington. "They stop just short of it,
cross their fingers and hope everything is OK."
Scrambling to salvage the department's reputation, USDA officials
Thursday ordered a battery of new tests on the suspect animal.
And Jim Rogers, a spokesman for USDA's Animal and Plant Health
Inspection Service, said the agency is reviewing its approach to mad
cow cases.
That news comes none too soon for U.S. beef producers, who have been
struggling to re-open foreign markets closed to them after the first
mad-cow scare.
The "fogginess" created by the USDA's handling of this case "messes
with the credibility of our strict standards." said Shane Sklar,
executive director of the Independent Cattlemen's Association of Texas.
Can cause horrific disease
Mad cow disease sparks such concern because humans who eat infected
beef can develop a horrific disease, known as variant Creutzfeldt-Jakob
disease.
When USDA officials encountered their first suspected case of bovine
spongiform encephalopathy - better known as mad cow disease - in
late 2003 in a cow from Washington state, the agency used what's known
as the immunohistochemistry or IHC test to confirm the animal had the
disease.
After the IHC test came up positive, regulators then went further and
conducted what's known as a Western blot analysis, a procedure used
widely in Europe and Japan.
They also asked a lab in Weybridge, England, considered the world's
foremost testing facility for the disease, to verify the results.
The cow was found to be infected, and more than 50 countries closed
their borders to U.S. beef exports.
In response, the USDA launched a program in June 2004 to screen more
widely for the disease, using a procedure known as a "rapid test." More
than 381,000 head of cattle have been tested since that time.
Rapid tests from three animals produced potentially troubling results.
USDA officials checked those initial results by using the IHC test,
what they have called the "gold standard." A cow singled out by the
initial test as the most likely to be infected was tested twice.
The IHC tests were negative on all three animals. Last November,
officials announced the most suspicious-looking cow was free of the
disease.
USDA officials did not employ the Western blot test to further verify
the IHC results, contending the two tests are "equally effective."
Rogers noted that since a Western blot test had confirmed the results
of an IHC analysis on the Washington cow, agency officials believed
they had all the necessary protocols in place.
Many experts say both tests are needed. At Weybridge, officials use the
IHC test but employ others as well, including variations of the Western
blot method.
Enhanced test
Adriano Aguzzi, a professor of neuropathology and director of the Swiss
National Creutzfeldt-Jakob Disease Surveillance Center in Zurich,
Switzerland, said in an e-mail that IHC can be as sensitive as the
Western blot method "in certain specific instances."
Aguzzi's institution, however, routinely runs a Western blot test
enhanced with another step "on every suspect case, because of its
unrivalled specificity and because - in most cases - we find it to
be much more sensitive than immunohistochemistry."
In the months since the November announcement, the USDA came under
intense pressure from organizations such as Consumers Union for failing
to conduct a Western blot test on the suspect cow.
Activists at Consumers Union pointed to reports in veterinary
literature which suggested IHC could miss some cases.
Michael Hansen, a senior research associate with Consumers Union, says
he confronted USDA officials about the issue during the June 6 meeting
of Institute of Medicine of the National Academies.
Then, that same week, the Agriculture Department's inspector general,
who has been monitoring the department's performance in screening for
mad cow disease, ordered USDA officials to retest samples from all
three cows that had produced questionable results last year using the
Western blot method.
What prompted that action by Inspector General Phyllis Fong's office is
not entirely clear. The retesting was done quietly. As late as June 9,
Agriculture Secretary Mike Johanns was referring to "that single cow"
in Washington state that had been found stricken with the disease.
Late Friday evening, USDA officials announced that a Western blot test
conducted on the cow declared clear of the disease last November was
showing what was described as a "weak positive."
Hansen scoffs at that designation: "You don't say someone is a little
bit pregnant."
Thursday evening, USDA officials announced that the Weybridge
laboratory will perform its own IHC tests, as well as three variations
of the Western blot, while USDA officials will conduct their own tests.
And they're reviewing how they will handle future cases.
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TC
Feds skipped key mad cow disease test in 2004 case