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We Should Trust The USDA?

Mike

Well-known member
USDA explains BSE test discrepancies

Ames’s “experimental” IHC positive in November but not announced

Agency still tracing origin of mad cow case

By Pete Cilento
Foodmarket News
[email protected]


Serious questions regarding the Agriculture Department’s mad cow testing procedures have emerged after Friday’s announcement of the second case of bovine spongiform encephalopathy in the United States. The incongruity between the original immunohistochemistry tests and the subsequent Western blot, as well as the revelation of a positive rapid IHC test in November -- which was concealed by the USDA’s Ames, Iowa, lab technicians for seven months -- led several to question the effectiveness of the USDA’s testing protocol for BSE.

Further adding fuel to the fire was Agriculture Secretary Mike Johann’s disclosure that the Weybridge, England, laboratory where the sample was sent for confirmatory testing itself performed an IHC test which was positive, as opposed to the two negative IHC tests announced by the USDA in November. The Weybridge lab also confirmed the sample positive for BSE via the more comprehensive Western blot test.

Agriculture Secretary Mike Johanns and veterinary doctors from the U.S. and the U.K. attempted to explain the discrepancies in a press conference Friday. Johanns offered several possible explanations for the clash between the two iterations of IHC testing across the Atlantic.

Johanns stressed that the IHC test used by the USDA was formulated before the first case of mad cow disease in 2003, and utilizes a different set of antibodies than the Weybridge IHC test.

Variation in test conditions could also yield different results in two IHC tests, said Johanns. Factors such as temperature, chemicals used, and length of antibody exposure could all produce discrepancies in the two test results. Though Johanns said the USDA froze the sample and that in the future it would study the effects before doing so, he said the freezing in this case did not affect results.

Johanns also addressed the fact that no announcement was made after an experimental IHC test on the sample tested positive in November.

“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,” explained Johanns. “Again, appropriate protocols relating to additional testing for research will prevent a similar situation in the future.”

As for the incongruity between the USDA’s two IHC tests and the Western blot performed in June both in the U.S. and in England, the agency said that the abnormal prion deposits in the animal’s brain may not have been uniformly distributed. An uneven distribution could result in differing IHC results, because unlike the Western blot, which would detect prion deposits anywhere in the brain, the IHC targets a specific sector of the brain.

Though the two IHC tests the USDA ran in November were negative, the IHC performed in June in the Weybridge lab was positive. Additionally, the USDA ran another IHC test on the sample on June 13, 2005, which was also positive. All standard Western blot tests performed by both nations returned positive results.

When pressed by the media on the state of origin for the cow, the USDA would not confirm any specific locations. It would only say that there was “no evidence” the cow was an import, but said it was still conducting DNA tests to determine the state and herd of origin. Several media reports since November have indicated the cow was from the state of Texas, but the USDA did not offer confirmation.
 

flounder

Well-known member
WHY do you reacon they put Dr. Detwiler out to pasture $$$


NOW, let us look at another BSE ROUNDTABLE DISCUSSION by USDA et al in the year 2003, please note the BSE science on IHC testing then, and then compare to now, and then ponder those other 9,200 cattle of the infamous June 2004 BSE cover-up program, that did not have rapid testing or WB, just IHC, the lease likely to find BSE/TSE ;

USDA 2003

We have to be careful that we don't get so set in the way we do things that
we forget to look for different emerging variations of disease. We've gotten
away from collecting the whole brain in our systems. We're using the brain
stem and we're looking in only one area. In Norway, they were doing a
project and looking at cases of Scrapie, and they found this where they did
not find lesions or PRP in the area of the obex. They found it in the
cerebellum and the cerebrum. It's a good lesson for us. Ames had to go
back and change the procedure for looking at Scrapie samples. In the USDA,
we had routinely looked at all the sections of the brain, and then we got
away from it. They've recently gone back.
Dr. Keller: Tissues are routinely tested, based on which tissue provides an
'official' test result as recognized by APHIS
.

Dr. Detwiler: That's on the slaughter. But on the clinical cases, aren't
they still asking for the brain? But even on the slaughter, they're looking
only at the brainstem. We may be missing certain things if we confine
ourselves to one area.


snip.............


Dr. Detwiler: It seems a good idea, but I'm not aware of it.
Another important thing to get across to the public is that the negatives
do not guarantee absence of infectivity. The animal could be early in the
disease and the incubation period. Even sample collection is so important.
If you're not collecting the right area of the brain in sheep, or if
collecting lymphoreticular tissue, and you don't get a good biopsy, you
could miss the area with the PRP in it and come up with a negative test.
There's a new, unusual form of Scrapie that's been detected in Norway. We
have to be careful that we don't get so set in the way we do things that we
forget to look for different emerging variations of disease. We've gotten
away from collecting the whole brain in our systems. We're using the brain
stem and we're looking in only one area. In Norway, they were doing a
project and looking at cases of Scrapie, and they found this where they did
not find lesions or PRP in the area of the obex. They found it in the
cerebellum and the cerebrum. It's a good lesson for us. Ames had to go
back and change the procedure for looking at Scrapie samples. In the USDA,
we had routinely looked at all the sections of the brain, and then we got
away from it. They've recently gone back.

Dr. Keller: Tissues are routinely tested, based on which tissue provides an
'official' test result as recognized by APHIS
.

Dr. Detwiler: That's on the slaughter. But on the clinical cases, aren't
they still asking for the brain? But even on the slaughter, they're looking
only at the brainstem. We may be missing certain things if we confine
ourselves to one area.


snip...


FULL TEXT;


Completely Edited Version
PRION ROUNDTABLE


Accomplished this day, Wednesday, December 11, 2003, Denver, Colorado


2005


National Veterinary Services Laboratory (NVSL) Immunohistochemistry (IHC) Testing Summary

The BSE enhanced surveillance program involves the use of a rapid screening test, followed by confirmatory testing for any samples that come back "inconclusive." The weekly summary below captures all rapid tests conducted as part of the enhanced surveillance effort. It should be noted that since the enhanced surveillance program began, USDA has also conducted approximately 9,200 routine IHC tests on samples that did not first undergo rapid testing.


http://www.aphis.usda.gov/lpa/issues/bse_testing/test_results.html


TSS
 

Econ101

Well-known member
We already know the USDA's use of the "best available science" is a fraud.

They need to get a little more competent or fire some that are getting in the way.
 

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