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From: TSS (216-119-132-19.ipset12.wt.net)
Subject: Possible mad cow case shocks cattle industry
Date: November 19, 2004 at 6:44 am PST

-------- Original Message --------
Subject: Possible mad cow case shocks cattle industry
Date: Fri, 19 Nov 2004 08:26:45 -0600
From: "Terry S. Singeltary Sr."
Reply-To: Bovine Spongiform Encephalopathy
To: BSE-L@UNI-KARLSRUHE.DE


##################### Bovine Spongiform Encephalopathy #####################

Possible mad cow case shocks cattle industry


> The sample was sent to the National Veterinary Services Laboratory in
> Ames, Iowa, where it could take four to seven days to analyze. But the
> manufacturer of the screening test, Bio-Rad, told Reuters that the
> sample was screened twice, which makes it far more likely to be positive.
>

http://www.chron.com/cs/CDA/ssistory.mpl/business/2908555


USDA advised against mad cow test in 2002

By Steve Mitchell
United Press International

Published 7/13/2004 7:57 AM

WASHINGTON, July 13 (UPI) -- The U.S. Department of Agriculture in late
2002 warned against using the same mad cow disease test the agency now
is using in its expanded surveillance program for the deadly disorder,
United Press International has learned.

The USDA said governments should not authorize the test, which is
manufactured by Bio-Rad Laboratories in Hercules, Calif., because it can
give false positives -- results that are ruled negative on follow-up
testing -- and "will cause loss of consumer confidence in beef and beef
products," the agency wrote in a letter to the World Organization for
Animal Health in Paris.

The OIE, as it is known by its French initials, establishes
international standards for animal disease issues.

The USDA recommended countries employ a different test manufactured by
the Swiss firm Prionics -- a test the agency has licensed but has not
yet put into use. The USDA's reason for the delay is the Prionics test,
which has not yielded a false positive in more than 20 million tests in
Europe, still must pass through the agency's validation procedures.

Concerns about false positives with the Bio-Rad test became a reality
recently during the first month of the USDA's expanded surveillance
plan, launched June 1 in response to the only confirmed U.S. case of mad
cow last December. The agency reported two preliminary positive results,
which caused concern among the public and havoc in the cattle futures
markets until both were ruled negative on follow-up testing several days
later.

So far, seven of the 12 state laboratories participating in the USDA's
mad cow surveillance plan are using the Bio-Rad test and the remaining
five are expected to opt for the test when they begin testing operations.

Experts on testing and mad cow disease have suggested one reason the
USDA might have opted for Bio-Rad is the same reason it advised against
it in 2002: its potential to yield false positives.

By releasing preliminary positives -- or inconclusives, as the USDA has
deemed them -- that are later ruled negative, the agency could
desensitize markets, consumers and foreign trading partners to real
positive cases when and if they occur, the sources said.

"Bio-Rad was approved as a way of getting people used to a possible case
if there ever was one," a veterinarian with expertise in mad cow disease
told UPI.

"They (USDA officials) know it has a high false positive rate ... The
more inconclusives they have, the easier it is to 'mix something up' and
have all negative tests," said the veterinarian, who requested anonymity.

The veterinarian's comments were echoed by other experts in this field,
who also declined to be named.

USDA spokeswoman Julie Quick did not respond to UPI's question of
whether this was the agency's intended strategy. However, John Clifford,
USDA's chief veterinary officer, acknowledged at a recent news
conference that release of the inconclusive results could have that affect.

"We want to minimize the impacts upon the markets," Clifford said. "We
feel like that after we get this information out there a couple of times
that hopefully it will continue to minimize that impact."

To date, more than 15,000 cows have been tested under the surveillance
plan and USDA officials have said they expect many more false positives
as the agency seeks to conduct thousands of mad cow tests per week over
the next 12 to 18 months.

Mad cow disease is otherwise known as bovine spongiform encephalopathy
or BSE. Officials have said they also expect to find additional BSE cases.

Consumer groups and some members of Congress expressed concern about the
USDA's decision to use the Bio-Rad test after the two false positives.

Sen. Conrad Burns, R-Mont., recently sent a letter to Agriculture
Secretary Ann Veneman urging her "to seriously consider the reliability
of your tests and to rigorously evaluate BSE screening tests used
internationally that may offer more accurate results."

The concern to consumers is people can contract an incurable brain
disorder called variant Creutzfeldt Jakob disease from eating meat
infected with the mad cow pathogen. More than 150 people worldwide have
become infected, but none of the cases has been linked to U.S. beef.

"Why are we using Bio-Rad instead of Prionics if they are as bad as the
(USDA) would have us believe with all these 'inconclusives?'" asked
Terry Singletary, coordinator of CJD Watch, an advocacy group for
patients and family members. His mother died of a rare form of CJD
called Heidenhain Variant, which has not been linked with mad cow disease.

"Do they really want to find all the cases, or are we just playing a
(public relations) game?" asked Singletary, who has been sharply
critical of the USDA's approach to mad cow. "How many more are we going
to expose to this deadly pathogen?"

Brad Crutchfield, Bio-Rad's vice president, said the science and
experience with his company's test in Europe establishes its soundness
and reliability. Bio-Rad has yielded false positives only once every
300,000 tests, he said, adding that the false positives will decrease as
the U.S. labs acquire more experience.

"The issue has nothing to do with the test, it has to do with the
notification process," Crutchfield said, referring to the USDA's
decision to notify the public of inconclusive results before they were
confirmed or ruled out with confirmatory tests.

Heads of several state labs contacted by UPI said the agency allowed
them to choose among five licensed rapid tests, including Bio-Rad's.
However, outside testing experts said it was curious that all the labs
chose the same test.

"It is slightly peculiar that it went all to one supplier for no other
reason than you would want different tests because they give different
results," said Roger Rosedale, chairman of Microsens Biotechnologies, a
company in London that manufactures technology used in tests for
detecting mad cow disease and similar disorders. One of Microsens'
clients is Idexx Laboratories, which makes a competing mad cow test to
Bio-Rad and Prionics.

At the time the labs were making their choices, the USDA said Bio-Rad
was the only test the agency had "field tested," which apparently is a
prerequisite for putting the tests into use.

The Bio-Rad test "was the only one that had been field tested, so that's
limiting," said USDA's Quick. So although the USDA had licensed the
other rapid tests, they may not have been available for use even if the
laboratories had selected them.

The department also purchased the equipment needed to run the Bio-Rad
test for the labs, some of which otherwise would not have been able to
afford the machinery due to budget constraints.

A source with an American company that manufactures tests for detecting
animal disease said it was unusual for the USDA to approve a test and
then require field testing. Field trials are usually done before
approval, the source said.

"With other tests, if you get USDA approval, you're all set," the source
said. "This is something new."

Asked why the USDA was not using the Prionics Check test, as it had
recommended in the 2002 OIE letter, Quick said it is still being "field
tested." In the letter, however, the agency did not cite the need for a
field test or validation procedure.

"Certain tests, such as the rapid tests, may not give an accurate
picture of the BSE situation in a country or zone," the USDA wrote. "It
is well known that certain rapid tests such as the Enfer and Bio-Rad
tests have recorded false positive BSE results. For BSE-free countries
or zones, the use of rapid BSE tests that give false positive results
will cause loss of consumer confidence in beef and beef products."

A better approach would be to use the Prionics Check test, the agency
wrote.

"For BSE free countries or zones, the use of histopathology,
immunohistochemistry and the Prionics 'check' immunoblot test would
provide a definitive diagnosis of a BSE suspect case," the letter stated.

Quick insisted the agency's statement was not intended to recommend
against the Bio-Rad test. Instead, she said, it was meant to recommend
that countries not simply rely on rapid screening tests as a way to
confirm a case of mad cow disease.

No other testing experts UPI contacted interpreted the statement that
way and Quick, who acknowledged she was not familiar with the technical
details of the tests, declined to make Clifford or other USDA officials
available to discuss the issue or offer clarification.

The USDA's decision not to release the samples from the two
inconclusives for verification by outside labs has also come under
question. The agency used a test called immunohistochemistry, or IHC, to
determine the animals were not infected with mad cow, but experts said
this is not always a foolproof test and it can miss cases.

Markus Moser, Prionics' chief executive officer and a molecular
biologist, noted that Germany was considered BSE-free when using the IHC
test. When officials there began using the Prionics rapid test in 2000,
he said, they found several cases and so far have detected more than 300
infected animals.

Stuart Wilson, Microsens' scientific director and a molecular
pathologist, noted in a document he recently prepared on false positives
that there have been instances when Bio-Rad was used more than a few
months before the animal developed symptoms and they were found
correctly to be positive, but IHC incorrectly ruled them negative.

"In a cow that you don't know is infected or not, it can always appear
IHC positive (or negative) simply by changing the IHC timing," Wilson
wrote in the document.

"This was one of the biggest problems with investigating tonsils in
asymptomatic humans in the United Kingdom," the document said, referring
to a recent study that indicated as many as 3,800 people in England may
be unwittingly incubating vCJD.

In the December mad cow case, the USDA had the results confirmed by the
Weybridge laboratory in the United Kingdom, which is one of the three
mad cow disease testing reference laboratories recognized by the OIE.
The other two are in Switzerland and Japan.

"It must by definition create doubt if they're not allowing any other
... OIE reference laboratory have access to them," Rosedale said. "It's
not to suggest (the USDA) guys are not competent, but why would they not
release it?"

--

Steve Mitchell is UPI's Medical Correspondent. E-mail sciencemail@upi.com

Copyright © 2001-2004 United Press International

http://www.upi.com/view.cfm?StoryID=20040712-060601-3233r

TSS

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