DC, July 28, 2005 (ENS): The U.S. Department
of Agriculture is investigating another "non-definitive”
test result for mad cow disease, saying Wednesday that
further testing is being done in the United States and
England. The brain sample was taken by a private veterinarian
in April, but not sent to the USDA until last week because,
agriculture officials said, the veterinarian "forgot"
to send it in for testing.
USDA Chief Veterinarian John Clifford told reporters
that the animal did not enter the animal feed or human
food supply. He said the animal appears to have been
born in the United States.
The sample in question was taken from a cow that was
at least 12 years of age and experienced complications
during calving. The cow's age is important because it
was born before 1997 when restrictions were placed on
giving cattle feed containing the nervous system tissue
of other cattle.
The BSE infection is caused by misfolded proteins called
prions, found in nervous system tissues such as brains
and spinal cords. Mad cow disease spreads from one animal
to another by consumption of feed that has been contaminated
by these prions.
While it is always fatal, BSE can take years to develop,
so young animals are considered safer for human food
than older animals. The human form of the disease can
be transmitted if a human being eats BSE infected meat.
The private veterinarian treated the sample with a
preservative, which readies it for testing using the
immunohistochemistry (IHC) test - an internationally
recognized confirmatory test for BSE. Neither the rapid
screening test nor the Western blot confirmatory test
can be conducted on a sample that has been preserved,
While Western Blot or rapid screening tests are not
possible on the preserved sample, an immunohistochemistry
(IHC) test has been run, though the result was not conclusive.
The IHC will be repeated at the National Veterinary
Services Laboratory in Ames, Iowa and the World Reference
Laboratory at Weybridge, England. Results are expected
The rules governing chemical preservation of samples
were changed in June when another inconclusive sample
of a Texas animal turned out to be positive when tested
with all three procedures.
The American Meat Institute (AMI) said that whatever
the result, consumers and trading partners should not
be concerned because "beef is safe from BSE, and
even if the test ultimately confirms positive, the safety
of the U.S. beef supply is unchanged."
"The beef we eat, like steaks, roasts and ground
beef, is safe. These products have never been associated
with a BSE-related human illness,” said AMI Foundation
President James Hodges.
“People in Europe who became ill likely consumed
brains or other infected tissues early in the BSE epidemic
because the human health risk was not recognized,”
Hodges said of the 150 people who have died from the
human form of BSE, known as variant Creutzfeldt-Jakob
Disease. “By contrast, these parts are removed
in the U.S. and do not enter the food supply.”
Hodges stressed that the age of the animal indicates
that if it is indeed positive for BSE, it was likely
exposed to the BSE agent through feed before the new
feed restrictions went into effect in 1997.
He asserted that due to the current restrictions on
feeding nervous system tissues to ruminant animals such
as cows, “BSE is on its way out in North America.”
But lawmakers and consumers groups are not so sure.
Senator Tom Harkin, a Democrat representing the beef
producing state of Iowa, said this type of mistake invites
Japan and other countries to question the safety of
When the first U.S. case of mad cow disease was discovered
in December 2003, 53 countries including Japan banned
U.S. beef. The U.S. Agriculture Department has been
intensively negotiating for years to reopen that market.
The day before this suspect animal was identified to
the public, Harkin and fellow Democratic Senator Richard
Durban of Illinois called on the USDA to explain its
failure to fulfill commitments to expand testing for
mad cow disease.
The senators expressed concern that the USDA has apparently
abandoned plans to test clinically normal, aged cattle
as part of its BSE surveillance program despite public
statements to the contrary.
“USDA said they would test 20,000 aged cows that
appear healthy,” Harkin said. “I want to
know why these plans were scrapped and why they have
failed to publicly acknowledge this.”
Early in 2004, USDA had stated that it planned to test
20,000 clinically normal, aged cattle as part of their
expanded testing program. Also, in the FY2005 agriculture
appropriations bill, Congress urged that USDA include
this population of cattle as part of its surveillance
In other countries, a small but significant number
of clinically normal cattle over 30 months of age have
tested positive for BSE. While U.S. agriculture officials
had continued to say the USDA would test these normal
appearing older animals, the department has not begun
this testing to date.
"The government keeps telling Americans that they
can trust that their beef is safe from mad cow, even
going so far as to say that finding BSE is like searching
for a needle in a haystack," says Dr. Michael Hansen,
PhD, a senior scientist with Consumers Union, which
publishes "Consumer Reports" magazine.
"Yet, since the agency has so far failed to publicly
disclose any information whatsoever about the details
of the program," said Hansen, "it makes us
wonder how meaningful their search for the disease is
"We want to know exactly which cattle were tested
and whether or not they really represent the most valid
scientific sampling of the highest risk animals from
across the country," Hansen demanded on Monday
before the latest inconclusive result was made public.
He was responding to the previous case of the Texas
animal that tested positive for BSE in June.
"If the USDA wants to truly reassure the American
people, they should answer our questions," Hansen
said. "Their failure to do so would make us wonder
what the agency is hiding."
Clifford said Wednesday that the USDA's "enhanced
surveillance program" is working well.
"We are extremely gratified that to date, all
sectors of the cattle industry have cooperated in this
program by submitting samples from more than 419,000
animals from the highest risk populations," he
said. "To date, only one animal has tested positive
for the disease as part of the surveillance program.
These interlocking safeguards continue to protect our
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