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From: TSS ()
Subject: Fed MAD COW testing was marked by missteps
Date: June 25, 2005 at 6:43 am PST

June 24, 2005, 11:09PM

ANALYSIS
Fed testing was marked by missteps
By DAVID IVANOVICH
Copyright 2005 Houston Chronicle Washington Bureau

U.S. Agriculture Secretary Mike Johanns tried to calm the public, saying, "the animal did not get anywhere near the human food chain."
WASHINGTON - The U.S. Agriculture Department's investigation of an animal infected with mad cow disease was marred by a string of bad decisions and questionable lab work.

While USDA officials have been quick to try to reassure the public, critics say their handling of a diseased cow raises disturbing new questions about their ability to safeguard the nation's food supply.

Consider:

•Lab technicians in Ames, Iowa, twice performed what's known as the immunohistochemistry, or IHC test, and concluded the cow was free of the brain-wasting disease. But when experts in Weybridge, England, this week used that same test with more up-to-date methods they got a positive result.
•After their IHC tests showed negative for the disease, USDA officials ignored results from an "experimental" test that had a positive result.
•Officials failed to adequately segregate the carcass of the diseased cow from other animals during testing last November. This, as U.S. Agriculture Secretary Mike Johanns said Friday, made it "difficult to isolate the parts of the animal."
As Johanns would have it: "Science is ever evolving. It is not static. And as we learn more, we apply the knowledge."

But Michael Hansen, a senior research associate with Consumers Union, said USDA officials "almost sound like some Keystone Kops."

"You really wonder," Hansen said.

Mad cow disease, or bovine spongiform encephalopathy, sparks such concern because humans who eat certain parts of an infected cow, can develop a horrific disease, known as variant Creutzfeldt-Jakob disease.


388,000 screenings
Over the last year, USDA officials have screened more than 388,000 cows for the disease using what's known as the "rapid" test. When this cow tested positive using that method, USDA officials began a more thorough analysis.

Back in 2003, when confronted with the first case of mad cow disease in the United States, officials conducted an IHC test and then confirmed that result with another technique known as the Western blot method. They then sent samples to Weybridge for confirmation.

Last November, officials skipped the Western blot test and declared the animal free of the disease after the IHC test results were negative.

International experts on mad cow said a Western blot test should routinely be conducted on any suspected case, but USDA officials defended that decision, calling the IHC test the "gold standard."

Then, earlier this month, the Agriculture Department's inspector general, which has been monitoring the mad cow program, ordered the USDA to conduct a Western blot analysis.

Before the Friday announcement, Johanns questioned whether Inspector General Phyllis Fong had such authority. "If it's operational, then it's my domain," Johanns told The Associated Press. "She could recommend; she could strongly urge."


A new round of testing
Last week, USDA officials sent samples to Weybridge for analysis. Experts then conducted tests using both Western blot and IHC, yielding results indicating mad cow using both methods. Why were the results of the two labs so different?

In part, Johanns argued, that may be because the telltale abnormalities were spread out in the diseased cow's brain "making it possible for one sample to test negative while another sample might test positive."

To detect those abnormalities, scientists use antibodies which bind to the problem proteins and highlight them. The Weybridge experts use different antibodies than those employed by the scientist at Ames.

"The protocol we developed just a few years ago to conduct the tests, including the type of antibody used, might not be the best option today," Johanns conceded.

Danny Matthews, a scientist with Britain's Veterinary Laboratories Agency in Weybridge, couldn't explain why the Ames lab didn't detect the disease.

"It isn't just the antibodies, because essentially this is a bit like baking a cake," Matthews said. "You need all the ingredients to work together to produce a finished product, and it can be compromised if there is a slight deficiency in one step in the process."

"What one needs to do is obviously look at what went wrong," Matthews said.

USDA officials also, for the first time, revealed that an "experimental" test had also indicated the disease.

"Because the test was not validated, and because it followed the two approved IHC tests that came out negative, the results were not reported out of the lab," Johanns said.

The critics say the testing fumbles raise concerns about the screening process.

"How can we be sure they were really negative?" asked Craig Culp, a spokesman for the Center for Food Safety in Washington.

After all, Craig said, here is a cow that was "negative in November that is positive in June."

david.ivanovich@chron.com

http://www.chron.com/cs/CDA/ssistory.mpl/nation/3240422

TSS






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