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From: TSS (
Date: November 24, 2004 at 7:18 pm PST

-------- Original Message --------
Subject: Experts doubt USDA's mad cow results
Date: Wed, 24 Nov 2004 21:27:37 -0600
From: "Terry S. Singeltary Sr."
To: Bovine Spongiform Encephalopathy
CC: cjdvoice

Experts doubt USDA's mad cow results

By Steve Mitchell
Medical Correspondent

Published 11/24/2004 4:34 PM

WASHINGTON, Nov. 24 (UPI) -- U.S. Department of Agriculture officials said a cow that initially tested positive for mad cow disease was found to be negative on follow-up tests, but both domestic and international experts told United Press International the way the agency handled the situation leaves them skeptical about the validity of the results.

"The testing process does indeed make experts scratch their heads," said Markus Moser, a molecular biologist and chief executive officer of the Swiss firm Prionics, which manufactures tests for detecting mad cow disease, also known as bovine spongiform encephalopathy.

"I think some, but not all, BSE people internationally have some degree of cynical de facto doubt about everything the United States does or doesn't do, mostly as a result of seeing so many similar situations where countries at risk deny and deny and deny and then end up having big problems," said Elizabeth Mumford, a veterinarian and BSE expert at Safe Food Solutions in Bern, Switzerland, a company that provides advice on reducing mad cow risk to industry and governments.

Several countries, including Germany and Austria, that had been thought to be free of the disease, found out it was circulating in their herds after they initiated large-scale testing.

The U.S. cow in question tested positive last week on two so-called rapid tests manufactured by Bio-Rad Laboratories in Hercules, Calif. The USDA said Tuesday the animal had tested negative on more sophisticated confirmatory tests called immunohistochemistry or IHC tests.

John Clifford of the USDA said in a statement that the negative IHC results "makes us confident that the animal in question is indeed negative."

A U.S. veterinarian knowledgeable about mad cow tests told UPI that experts she has spoken with are "very, very skeptical about" the USDA's negative test result.

The veterinarian, who requested anonymity because she feared repercussions for speaking out against the USDA, said the skepticism arose because the agency did not run another kind of mad cow test called a Western blot. The test sometimes can pick up positive cases that IHC misses and the agency has used it in the past to rule out suspect cases.

Moser said a Western blot test would make sense for the United States, where the prevalence of mad cow is thought to be low. Other countries -- including Australia, New Zealand, Canada and Mexico -- that are either free of the disease or have low rates, have elected to use the Western blot as part of their surveillance programs, he said.

The veterinarian said concerns also have emerged because the USDA has not made a sample from the cow in question available for examination by outside experts. She added that the USDA did not notify state officials, as officials previously said they would about positive results on rapid tests.

Knowledgeable people are saying "wait a minute, this doesn't add up here," the veterinarian said.

At stake is the $70 billion U.S. beef industry, including a $3.3 billion export market. More than 60 countries, including Japan, closed their borders to U.S. beef last December after the first -- and so far only -- U.S. case of mad cow was detected.

Asked whether state officials were notified, USDA spokesman Ed Loyd told UPI the agency had not released any information about the cow in question. Loyd also said the false positives on the rapid test were not unexpected. Since June, the USDA has reported three false positives out of more than 121,000 cows tested.

Bio-Rad spokeswoman Sam Kennedy told UPI the company was unfamiliar with the details of this incident and thus could not comment.

Mumford said experts were surprised the USDA did not send samples from the cow in question for independent analysis by one of the three worldwide labs recognized as the foremost authorities on mad cow testing by the World Animal Health Organization. One of these facilities is located in Weybridge, England, where the USDA had sent the first U.S. case of mad cow disease for confirmation in December 2003.

Loyd said USDA officials who would know whether USDA planned to release a sample for verification by an outside party could not be reached Wednesday.

"Full transparency and cooperation would certainly promote the idea internationally that the U.S. is doing everything it can do," Mumford said. "But somehow the U.S. consumer doesn't seem to think that way, or has been appeasable at least up until now, so there seems to be no impetus to do anything more."

The concern is humans can contract a fatal brain illness known as variant Creutzfeldt Jakob disease from eating beef products contaminated with the mad cow pathogen.

Moser said despite USDA's reliance on the IHC test results, repeated negatives on that test does not necessarily rule out the cow being infected.

"The reason for this is that the IHC test ... is done on a different piece of tissue" than that used for the rapid test, he said. Prions, the pathogen thought to cause mad cow disease, tend to concentrate in a region of the brain called the obex, so the different outcomes of the different tests could be due to sampling a brain region that contains little or no prions.

This could be made worse if the animal had lay dead for several days before its brain was collected. The brain might be so degraded that it would be difficult to locate the obex region for confirmatory testing and a sample might mistakenly be taken from a region that contains no prions.

"So with these samples, the confirmatory testing would be even less reliable, not because of the confirmatory test itself, but because of the sampling," he said.



Copyright © 2001-2004 United Press International

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