Mad Cow Missteps Shake Confidence in U.S. Beef
WASHINGTON, 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, said Clifford.
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 next week.
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 U.S. beef.
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 program.
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 at all."
"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 food supply."
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