# Cwd suspect false positive ?



## terry (Sep 13, 2002)

Published November 19 2010 Wisconsin DNR to continue CWD testing The Wisconsin DNR made plans to take deer tissue samples this weekend after a screening test showed a possible case of chronic wasting disease at a game farm near Ashland. Even though that test turned out to be a false positive, the DNR will go ahead and take samples from hunter-killed and car-killed deer within a 10-mile radius of Ashland.


The Wisconsin DNR made plans to take deer tissue samples this weekend after a screening test showed a possible case of chronic wasting disease at a game farm near Ashland. Even though that test turned out to be a false positive, the DNR will go ahead and take samples from hunter-killed and car-killed deer within a 10-mile radius of Ashland.

Hunters supplying samples for testing will be able to track results at www.dnr.wi.gov. Test results will take three to four weeks to be posted.

Here is a list of sampling stations where hunters can take deer for disease testing Saturday and Sunday:

Anglers All, 2803 Lakeshore Drive E., Ashland

Pearces Sausage Kitchen, 61327 Dahlstrom Road, Ashland

Woodys Taxidermy, 1109 Vaughn Ave., Ashland

Bayside Taxidermy, 1110 Lakeshore Drive, Ashland

Chequamegon Taxidermy, 73740 Strecker Road, Washburn

Brian Weber Processing, 29125 State Highway 137, Ashland

Ino Bar, 19020 U.S. Highway 2, Ino

Washburn Holiday Station, 606 W. Bayfield St., Washburn




http://www.duluthnewstribune.com/event/article/id/184347/group/Sports/



The Wisconsin Veterinary Diagnostic Lab - WVDL - involved in controversy over interpreting CWD test results and public disclosure.

An article on Wisconsin CWD test results by Associated Press reporter, Robert Imrie, has brought to light concerns over test procedures, test accuracy, and the reliability of test information released to hunters and the general public. The controversy surrounds 117 deer that initially tested positive on the new IDEXX rapid-screening test put into place by the DNR for the 2003 season. Because the older IHC test did not confirm those positive results, the protocol followed by the agency and its testing lab (WVDL) determined that the IDEXX test results were false. In fact, 74% of the IDEXX positives were eventually determined to be false - only 26% were confirmed by the older test. This low correlation between the two tests flies in the face of the results of the USDA trials of the test that showed almost 100% agreement between the two tests. Without a high correlation between the new IDEXX test and the older IHC test, the IDEXX would not have been certified for use.

Among the sources contacted in the Imrie investigation were some leaders in a DNR watchdog group called CALFARR (Citizens and Landowners for a Rational Response) who have long opposed the extreme response by the agency to the discovery of CWD in southern Wisconsin. The group has been conducting their own investigation into reporting failures and inconsistencies. On March 9th, they lodged a formal appeal with State Senate leader Erpenbach claiming a "hunters right to know" ALL of the results of the screening tests - not just those the DNR chose's to release. CALFARR believes that hunters who voluntarily submit samples for testing are entitled to full disclosure of test results - not a filtered version.

The IDEXX test only screens for CWD Suspects? The DNR and its Lab - the Wisconsin Veterinary Diagnostic Lab - are arguing that the IDEXX test only produces a "suspect" result and thus it would be misleading or confusing to report such results to hunters.

What is odd about this position is that IDEXX itself makes quite strong representations of the accuracy of its CWD test. Its web site reports that the "proven IDEXX ELISA" CWD test is extremely accurate: " . . . 98.8% sensitivity and 100% specificity (sensitivity validated through IHC confirmation testing)."

IDEXX Laboratories claims on their website that every deer from data sets used in IDEXX test validation with an absorbance value over .21 has also tested positive using IHC testing. This represents a specificity of 100%. The confirmation testing data the company used to gain USDA certification are on file with the firm. Positive and negative controls are provided in each test. Positive controls demonstrate the presence of CWD and react to give IDEXX values >0.40, and negative controls demonstrate the absence of CWD and give IDEXX values less than 0.15.

IDEXX ELISA technology could offer far greater sensitivity and reliability than the older IHC methods. The older IHC method suffers from potential sampling error plus it involves human subjectivity in interpreting the results. In IHC, a paper thin slice is taken from the tissue for microscopic examination. There is always a possibility that the paper thin slice fails to capture deformed CWD prions that may be present in the larger homogenized tissue sample used for IDEXX testing. Several sections must be taken through various areas of the same tissue used for ELISA in order for IHC to be accurate. If the error doesn't occur at this sampling stage, it may occur in the reading of the slide. While science based, this reading is an art form that depends greatly upon the technician's experience and intellectual discipline. As in radiology, two Radiologists may disagree on the interpretation of an x-ray film.

ELISA technology on the other hand - uses a larger tissue sample and homogenizes it. Thus it involves a more representative sample of the larger piece of tissue. The equipment provides a digital readout allowing no room for subjectivity or individual differences in technician experience or competence. A reading of .41 will be what it is no matter who reads it.

Public records from the WVDL of IDEXX test result data showed 26 deer deemed "negative" for CWD by the Lab & the DNR had IDEXX results were more than twice the IDEXX CWD positive threshold! And 5 of these "negative" confirmations exceeded the IDEXX positive optical density threshold by a factor 5! (the positive threshold is an optical density reading of .21 . . . 5 of the rejected samples had densities exceeding 1.05).

So considering the ELISA design of the IDEXX test should reduce subjectivity and other sources of error, if a reading of 1.05 - 5 times the "suspect" threshold - turns out to be negative, wouldn't that cause a reasonable person to suspect something isn't working properly? Is the basic test is badly flawed in its construction or were gross errors were made by the technician? And if such a large discrepancy occurs - not just once - but five times, isn't something clearly amuck?

It would seem that unless the WVDL discovers and admits the possibility of technician error, it must consider that the IDEXX test itself may be unreliable. We know that the record of testing in Colorado using a similar ELISA test kit by an IDEXX competitor, Bio-Rad, has a near-spotless record of confirmatory testing (only 4 times in 47,000 cases did the Bio-Rad ELISA test and the IHC test fail to agree).

How Golden is the Gold Standard? The DNR and the WVDL often refer to the older IHC test as the Gold Standard - a test whose accuracy and reliability is beyond question. Thus we were surprised when reading a Colorado State CWD Surveillance study to come upon the following statement:

"Most reference tests used in validation studies are imperfect and are incorrectly termed gold standards. Many authors have shown that the use of these imperfect reference tests for the calculation of sensitivity and specificity of new tests result in estimates that are biased (Staquet et al., 1981; Enoe et al., 2000). In the simple case, where the reference test is imperfectly sensitive but perfectly specific (e.g., bacterial, viral, or parasite isolation), the sensitivity and specificity of the new test will likely both be underestimated."

This same study report also explains the difficulty in properly interpreting IHC results:

" . . . The IHC is time consuming and requires specialized technical skills. Furthermore, IHC interpretation is subjective and can be influenced by prior knowledge of the case and associated results from the screening tests. Several new rapid screening tests are being validated to complement available techniques for the purpose of large scale screening for these diseases. Some of these tests have been validated and are currently being applied in disease control programs in several countries. Other tests are currently being validated for both screening and confirmation of these diseases.

All of these tests require the collection of appropriate clinical specimens, mainly the appropriate obex site of brain tissue, or the region proximal to the cortex in lymph nodes. Selection of the appropriate clinical specimens (tissue type, amount of tissue collected, etc) is an essential component if these tests are to have good diagnostic accuracy. Furthermore, it is known that the prion agent of these diseases tends to be unevenly distributed in the tissue specimens."

What is your testing objective? Our internet research on this subject found an interesting a course outline on VETERINARY EPIDEMIOLOGY (Caution - long download time) that discussed, among other matters, how research objectives determine the type of procedures used. In employing a two test protocol, the lab may chose to run the tests parallel to one another or in series:

"Parallel interpretation With parallel test interpretation, an animal is considered to have the disease, if one or more tests are positive. This means the animal is being asked to prove that it is healthy.

Series interpretation With serial test interpretation, the animal is considered to have the disease if all tests are positive. In other words, the animal is being asked to prove that it has the condition."

From this it seems clear our Wisconsin officials are following a "series interpretation" strategy - thus the animal must test positive in both tests and "prove" it has the condition. It is not being asked to "prove" it is healthy. Thus our procedure means we can be very, very confident that every case we deem CWD positive is "in fact" CWD positive. We want to be quite sure we have no false positives.

On the other hand our procedure allows room for the possibility that some CWD negatives are "in fact" CWD positives. This is the direct result of our testing objective aiming to insure against false positives.

Thus we have a conflict of testing objectives. The DNR wants to be absolutely sure that when a deer is pronounced CWD positive, it is in fact CWD positive. Hunters - who request tests - want to know that when their deer is pronounced CWD negative, it is in fact CWD negative!

Another example of the needs of the Agency bureaucracy taking priority over the needs of hunters.

--Ross Reinhold, April 13, 2004 & April 29, 2004 [email protected]

Some information for this


http://www.caids-wi.org/IDEXX_cwd2.html


http://wildlife.state.co.us/NR/rdonlyres/8A40833F-5DC5-46FD-9A0F-36EF32582F67/0/Field_Valid.pdf



PLEASE BE ADVISED, test for prions in different species is still not an exact science, especially in most cases where to look NOT to find, as with the case of BSE in USA cattle. ...TSS



Tuesday, November 02, 2010 

BSE - ATYPICAL LESION DISTRIBUTION (RBSE 92-21367) statutory (obex only) diagnostic criteria CVL 1992

http://bse-atypical.blogspot.com/2010/11/bse-atypical-lesion-distribution-rbse.html



BIO-RAD

-------- Original Message -------- 
Subject: USA BIO-RADs INCONCLUSIVEs 
Date: Fri, 17 Dec 2004 15:37:28 -0600 
From: "Terry S. Singeltary Sr." To: [email protected]

Hello Susan and Bio-Rad,

Happy Holidays!

I wish to ask a question about Bio-Rad and USDA BSE/TSE testing and there inconclusive. IS the Bio-Rad test for BSE/TSE that complicated, or is there most likely some human error we are seeing here?

HOW can Japan have 2 positive cows with No clinical signs WB+, IHC-, HP- , BUT in the USA, these cows are considered 'negative'?

IS there more politics working here than science in the USA?

What am I missing?

-------- Original Message -------- 
Subject: Re: USDA: More mad cow testing will demonstrate beef's safety 
Date: Fri, 17 Dec 2004 09:26:19 -0600 
From: "Terry S. Singeltary Sr." snip...end

Experts doubt USDA's mad cow results

snip...END

WELL, someone did call me from Bio-Rad about this, however it was not Susan Berg. but i had to just about take a blood oath not to reveal there name. IN fact they did not want me to even mention this, but i feel it is much much to important. I have omitted any I.D. of this person, but thought I must document this ;

Bio-Rad, TSS phone conversation 12/28/04

Finally spoke with ;

Bio-Rad Laboratories 2000 Alfred Nobel Drive Hercules, CA 94547 Ph: 510-741-6720 Fax: 510-741-5630 Email: XXXXXXXXXXXXXXXXXX

at approx. 14:00 hours 12/28/04, I had a very pleasant phone conversation with XXXX XXXXX about the USDA and the inconclusive BSE testing problems they seem to keep having. X was very very cautious as to speak directly about USDA and it's policy of not using WB. X was very concerned as a Bio-Rad official of retaliation of some sort. X would only speak of what other countries do, and that i should take that as an answer. I told X I understood that it was a very loaded question and X agreed several times over and even said a political one.

my question;

Does Bio-Rad believe USDA's final determination of False positive, without WB, and considering the new atypical TSEs not showing positive with -IHC and -HP ???

ask if i was a reporter. i said no, i was with CJD Watch and that i had lost my mother to hvCJD. X did not want any of this recorded or repeated.

again, very nervous, will not answer directly about USDA for fear of retaliation, but again said X tell me what other countries are doing and finding, and that i should take it from there. "very difficult to answer"

"very political"

"very loaded question"

outside USA and Canada, they use many different confirmatory tech. in house WB, SAF, along with IHC, HP, several times etc. you should see at several talks meetings (TSE) of late Paris Dec 2, that IHC- DOES NOT MEAN IT IS NEGATIVE. again, look what the rest of the world is doing. said something about Dr. Houston stating; any screening assay, always a chance for human error. but with so many errors (i am assuming X meant inconclusive), why are there no investigations, just false positives? said something about ''just look at the sheep that tested IHC- but were positive''. ...

TSS

-------- Original Message -------- 
Subject: Your questions 
Date: Mon, 27 Dec 2004 15:58:11 -0800 
From: To: [email protected]

Hi Terry:

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

Let me know your phone number so I can talk to you about the Bio-Rad BSE test. Thank you

Regards

Bio-Rad Laboratories 2000 Alfred Nobel Drive Hercules, CA 94547 Ph: 510-741-6720 Fax: 510-741-5630 Email: 

=================================

END...TSS

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continued...


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## terry (Sep 13, 2002)

-------- Original Message -------- 
Subject: RE: Greetings again Professor Aguzzi ... TSS 
Date: Fri, 11 Mar 2005 09:19:49 +0100 
From: "Adriano Aguzzi" T
o: "'Terry S. Singeltary Sr.'"

Dear Mr. Singeltary

I sympathize with your wish to have the most sensitive assay implemented. However, the situation is not as simple as one might think. In the case of homogeneously distributed agent, biochemical detection of PrPSc is indeed likely to be more sensitive than immunohistochemistry. In the case of variegated, punctate distribution of the agent, morphological methods may indeed be an asset.

There are also issues of feasibility. In my laboratory, we routinely run phosphotungstic acid precipitation followed by Western blotting. However, this is an extraordinarily cumbersome procedure. The sensitivity is increased vastly, but the amount of work needed is also amazing. There is no way I could see our own procedure implemented for mass screening of millions of cows - unless one would draft a veritable army of laboratory technicians.

For all these reasons, while I see all your points, I feel unable to offer a strong public opinion in favor or against any specific methods. The final decision needs to take into account a variety of complex factors, and that is why I believe that it is best left to a panel of experts rather than to a public discussion.

Best regards Adriano Aguzzi 

____________________________ 

Prof. Adriano Aguzzi (MD PhD hc FRCP FRCPath) Institute of Neuropathology, University Hospital of Zürich Schmelzbergstrasse 12, CH-8091 Zürich, Switzerland Tel. ++41-1-255 2107 Tel. (direct line): 2869 Fax: ++41-1-255 4402, cellular: +41-79-320 1516 http://www.unizh.ch/pathol/neuropathologie/

-----Original Message----- 
From: Terry S. Singeltary Sr. [mailto:[email protected]] 
Sent: Thursday, March 10, 2005 20:18 
To: [email protected] 
Subject: Greetings again Professor Aguzzi ... TSS

Greetings again Professor Aguzzi,

A kind greetings from Texas. I hope you do not mind, but I must ask you several questions that will put you in the hot seat. Someone with credibility must come forward, such as yourself and speak out about the fact of the non scientific approach that USDA et al has take after the first diagnosis of BSE in the USA. This being, the refusal to use Western Blot on any suspicious or inconclusive BSE/TSE test. IHC is like a brain biopsy on trying to diagnose a CJD case. IF you take the sample from a part of the brain that is not that tainted, you will not get a reading. WB is much more sensitive, especially now with the Phospohtugstic acid precipitation step. IF Prusiners CDI was validated, who knows, that might even be more sensitive. Bottom line, we need you to come forward and state publicly ''the facts'' about USDA et al decision not to use WB on not only questionable samples, but on ALL samples. would you be willing to comment on this, to me or someone from the media (under the understanding it will be for the public)? I have several questions for you??? This is very very important in terms of human health (i.e. that nov. pos. pos. incl. neg cow).

P.S. there is one other top TSE scientist that has come forward and said what the USDA et al did with that cow was ''not logical''. (this will not be published for another 3 or 4 weeks). ONE other TOP TSE scientist saying the same thing would be much better for the public to hear and understand. anyway, does not hurt to ask, and i hope you come through here for us. I know this is a very loaded question, but times a wasting, and human health is at risk here...

thank you, with kindest regards,

I am sincerely,

Terry S. Singeltary Sr.

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

I would like to add to the first paragraph of Adriano Aguzzis comments. We have seen cases in Europe, where a positive result obtained with our Western blot rapid test(Prionics-Check WESTERN)could not be confirmed with IHC, but with the OIE-Western blot procedure, and we have also seen cases where the result could be confirmed by IHC but not by OIE-Western blot. As Adrino Aguzzi pointed out both IHC and OIE-Western have their limitations, but when combined and when performed well they pick up BSE reliably. In case of doubt, i.e. if a rapid test comes out consistently positive but an initial attempt of confirmation with IHC (or OIE-Western) fails, we recommend to routinely do a second test with the respective alternative method. This is the procedure most national reference centers, which are responsible for final confirmation of BSE cases, are following. Regards Markus Moser Prionics

-------- Original Message -------- 
Subject: Q&A Dr. Jean-Philippe Deslys USDA REFUSAL TO USE WB ON TEXAS COW WITH BSE SYMPTOMS (FULL TEXT) 
Date: Fri, 22 Apr 2005 11:53:47 -0500 
From: "Terry S. Singeltary Sr." Reply-To: Bovine Spongiform Encephalopathy 
To: [email protected]

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

Q&A Dr. Jean-Philippe Deslys

1. What is the standard regime for testing of suspect animals in the EU?

The regime is an initial screening by a high-output test, the Bio-Rad test. If a result raises suspicion, a confirmatory test is conducted with the Western blot test.

2. How long has this been the case?

Its a fairly recent development. Only recently has the Western blot test become sensitive enough, with the addition of phospohtungstic acid precipitation step. The Bio-Rad test (which Deslys helped develop) is extremely sensitive, and the standard Western blot is extremely reliable with high-signal test results. However, it had to be made more sensitive for low-signal (samples with low density of malformed prions) samples. It has been made more sensitive.

Reproducibility is the problem with the IHC test. It is not standardized; depending on the lab and its protocols, or even on the technician involved in the test, one can get conflicting results.

3. Is there a way to measure the three tests in sensitivity, accuracy and objectivity?

Historically, yes. The IHC was the gold standard at one point, but we have shifted to the Western blot. It requires less work, it is more sensitive and its results are reproducible. IHC relies on localization. If you have a weak signal case, you may get lucky and test a spot with a high concentration of prions. But the opposite it true too; you can miss an infection by testing a sample with low concentrations. Western blot is much better for low signal situations.

4. The USDA in 2003 used the Western blot to confirm the BSE case in Washington state, and it sent samples to the U.K. for independent testing. In the case this November, which it announced was negative, it instead used the IHC test and did not send samples to the U.K. Is this good science?

Its not logical. If you have two consecutive questionable screenings, you do another test. I can only advise, its managements duty at USDA to make the decisions. But when you have a discrepancy between the rapid test and the IHC, it is only logical to confirm it with another test.

5. We are hearing now about a new strain of BSE, atypical BSE or aBSE. Or BaSE. We have heard that IHC, the so-called gold standard, cannot detect the variant. Is this true?

Yes. There have been a few cases, one in Italy, one in Belgium, one here in France. It seems to only affect very old animals. The distribution in the brain is very different than we see with BSE, it looks very different. The IHC test will come back negative.

This his a very recent phenomenon. I have no opinion on its virulence. We do not know where it comes from. It could be a version of sporadic infection. Western blot caught them, but we would not even know it existed if we werent running systematic testing in the EU.

BSE was around for a long time before we caught it and by then, it was everywhere. It had become highly infectious. It probably amplified due to low-temperature rendering. The disease was recycled through the food chain, and was given time to amplify. By the time it was identified, even good cooking couldnt eliminate it.

I cant stress enough that systematic testing is necessary. Withdrawing all positives from the food chain is the best way to break the cycle.

What can happen with testing of only cattle that are clearly at risk is that several can remain undetected. Canada has tested about 30,000 head of cattle and has three positives. That would indicate that there are probably undiscovered cases. And what happens then is that the disease is allowed to amplify. You have to maintain testing.

When people choose to protect their economic interests over public health, it can have a boomerang effect. It happened all through Europe. They always deny; its not OUR problem, it is our neighbors problem. And then a single case is discovered and the public reacts. The economic results are devastating. It would be better to just assume BSE is present and use systematic testing as protection. That way, the public is reassured that it is not entering the food supply.

By systematic testing, I mean doing as we do in the EU, which is to test every animal over 30 months of age when it is slaughtered. In Europe, three times as many cases of BSE have been caught by systematic testing as by clinical testing (of clearly sick animals). In 2004, eight clinical cases were discovered, 29 were discovered at rendering plants, and 17 at slaughter. We should be using these tests as a weapon to protect the public and to give them assurance that the food supply is being protected.

6. USDAs list of specified risk materials excludes some products, like blood and bone meal, that are banned in the EU and UK. Is our feed supply safe?

With SRMs, where do you stop? Tests have found prions in meat, nerves travel through meat, and so on. The main infectivity is in the brain and the spinal cord. A blood and bone meal ban in animal feed is not really necessary, because except in cases of highly infective animals, it is unlikely that they are dangerous in themselves. If you combine systematic testing and targeted SRM removal, the brain and the spinal column in cattle over 30 months, you can have a compromise that is both safer and less costly than expanded feed bans.

Certainly, you can stop the spread of BSE with a total ban on offal. But it has to be a total ban. It cant be given to sheep or swine or poultry. It would be very expensive and virtually impossible to accomplish. You can have farmers using the wrong feed or transportation errors.

Systematic testing makes far more sense. I think of it as a thermometer. It not only allows us to catch the disease, it also allows us to monitor its progress. We can watch the levels of infectivity and if they start going up instead of down, we can take measures.

To an extent, our environment is contaminated. About 10 percent of wild animals test positive for TSEs. If you recycle these agents, they can evolve and get more dangerous. This is probably what happened with BSE. It wasnt very dangerous until it evolved to the disease we know today.

People complain that testing is very expensive. It is much more expensive to kill and test whole herds.

7. In your opinion, is infected feed the sole method of transmission of BSE, apart from the very rare maternal transmission?

Feed is the main problem. However, we are seeing some other possibilities, including through fat and greases. Calves are fed milk extracts, with the cream removed. To make it nutritious, they are using fat and grease from cattle.

(FOLLOW QUESTION: Would that allow BSE to develop into an infective level in cattle younger than 30 months, assuming they might be getting infected at a younger age?)

8. You were involved in a study that tested two primates who were fed infected brain tissue. One eventually died of TSE; the other survived. The press reported that the main finding was that it would take something on the order of 1.5 kilograms of infected matter to create an infection, but that seems to be an oversimplification. Could you explain it further?

The findings suggest that as little as five grams is enough to infect. The 1.5 kilo figure is the amount of infected tissue that would have to be ingested from an animal that would be below the threshold of infection, and would test negative. In other words, even though a younger animal may be developing the disease, it would take a considerable amount of tissue to transmit the disease.

An animal could be just below the testing level, and not be particularly dangerous. But that is why you have to keep testing. Once it reaches the threshold, it can become highly infective.

9. BSE is a pretty horrifying disease, but overall, it has killed less than 200 humans, and only a handful in recent years. Listeria, by comparison, kills thousands every year. Overall, how do you rate the threat from BSE?

The overall risk is not particularly high. Over two million infected animals went into the food chain in Europe, 400,000 of them before the SRMs, the brains and spinal column, were removed from the carcass. Less than 200 died, and less than 4,000 are at risk of developing the disease. What we know now is that one particle is not going to kill you. There has to be condensation of the prions to be truly dangerous.

This is not a sterile world. But the danger is that now that the crisis appears to be over, attention will turn elsewhere and that will allow the disease to amplify again. Just as we stopped paying attention to AIDS when medication seemed to control it, then were surprised when a new and more infectious and aggressive strain appeared, we could be surprised by a more serious strain of BSE. That is why I support systematic testing for the long term. The object is to keep levels of BSE low, and to recognize the danger if it suddenly pops back up. ...END

TSS

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-------- Original Message -------- 
Subject: hey there mike, some history on TERRY'S mad cow from TEXAS that was inconclusive ;-) 
Date: Wed, 02 Feb 2005 16:24:22 -0600 
From: "Terry S. Singeltary Sr." 
To: [email protected] CC: [email protected], [email protected]

Mike,

for your files for a later date;-)

I WANT THAT TEXAS MAD COW!

follow the thread. moser of prionics is in it and Everet of TAHC.

SO close, BUT yet so damn far away...TSS

-------- Original Message -------- 
Subject: US CHOICE OF MAD COW TEST QUESTIONED 
Date: Wed, 24 Mar 2004 16:12:06 -0600 
From: "Terry S. Singeltary Sr." 
Reply-To: Bovine Spongiform Encephalopathy 
To: [email protected]

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

US CHOICE OF MAD COW TEST QUESTIONED

The US plans to measure the incidence of mad cow disease in its cattle with a test that its own officials have said gives too many false positives. Some experts fear the choice reflects an official desire to downplay the impact of the first positive BSE tests that emerge, when they turn out not to be confirmed.

Last week the US Department of Agriculture (USDA) approved two tests, including one made by the Californian firm BioRad, for screening up to 300,000 cattle for BSE, starting in July. No more tests will be licensed for months. Announcing the testing plan, chief veterinary officer Ron DeHaven cautioned that "there will be positive results", many of them false.

BioRad's antibody-based test for the prion protein that causes BSE has given numerous false positives in Belgium and Germany. And in Japan only 8 of 113 cattle that repeatedly tested positive with BioRad were confirmed by slower tests that do not give false positives.

The USDA even wrote last May that "it is well known" that tests like BioRad's give false positives. It states that other kinds of quick tests are more suitable for testing for very low levels of BSE, which are expected in the US.

The second quick test approved by the USDA, made by Maine-based IDEXX, could also in theory give false positives. It remains unclear how reliable it is, because there has been little practical experience with the test so far. It is not yet approved for use in Europe, where the vast majority of BSE tests are done.

Debora MacKenzie, Brussels correspondent, New Scientist. tel +32-2-245-0412 fax +32-2-245-0552 mobile +32-49-754-0444

http://www.newscientist.com/ =====================


Greetings,

odd that the USDA et al approves two US-OWNED tests that are _known_ to give false positives, when they know other rapid TSE test are much more reliable. IT's like they purposely do not want to find any TSE in the USA bovine, so they pick the worst test available. The USDA own experts think BioRad is not suitable for supposedly BSE/TSE free and low incidence areas, so why did they choose this test and or the IDEXX, which i dont think has even been submitted to the EU for evaluation and has no commercial experiance to my knowledge. You could almost get the feeling they are deliberately skipping over Prionics for the least supperior TSE rapid test. I believe the Canadians finally did choose prionics. maybe paul or marcus might comment? seems if North America is going to be a consolidated BEEF trading market amongst themselves and expect to export there tainted products everywhere, they could at least come up with the same TSE rapid Test. how can one use a less reliable test and the other use a more reliable test, and it all be the same? i know there is a word Dehaven used, but it slips my mind now, (consolidated markets) that's not it, but you get the just of my thoughts, i think;-)...TSS

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-------- Original Message -------- 
Subject: Re: US CHOICE OF MAD COW TEST QUESTIONED 
Date: Thu, 25 Mar 2004 00:53:39 +0100 
From: Moser Markus 
Reply-To: Bovine Spongiform Encephalopathy 
To: [email protected]

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

Regarding your question about Canada's BSE-test choice for their official BSE surveillance, I can confirm that they chose the Prionics-Check Western rapid test. Regards Markus



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## terry (Sep 13, 2002)

-------- Original Message -------- Subject: Re: US CHOICE OF MAD COW TEST QUESTIONED 
Date: Thu, 25 Mar 2004 01:11:04 +0100 
From: Roland Heynkes 
Reply-To: Bovine Spongiform Encephalopathy 
To: [email protected]

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

Dear Terry,

odd that the USDA et al approves two US-OWNED tests that are _known_ to give false positives, when they know other rapid TSE test are much more reliable.

the BioRad-test seems to be the most sensitive rapid BSE test and it is clear that you "get" false positive results when you try to confirm its results with a less sensitive method like immune histochemistry. Poorly trained technicians of course may produce some false positives with the BioRad-test, but immune histochemistry produces many false negatives especially in the hands of not very experienced people. Generally the false negative and not the much fewer false positive results are the problem of all actually available BSE tests.

It is therefore not so easy to say, if the BioRad-test produced a false positive or if the confirming test produced a false negative result and which of them is more reliable. I for sure would not eat the meat of a cow which was seemingly false positive tested with the BioRad-test.

IT's like they purposely do not want to find any TSE in the USA bovine, so they pick the worst test available.

The BioRad-test is definitively not the worst test available (have a look on the EU results) and when a government does not want to get positive results, it uses immune histochemistry instead.

The USDA own experts think BioRad is not suitable for supposedly BSE/TSE free and low incidence areas, so why did they choose this test and or the IDEXX, which i dont think has even been submitted to the EU for evaluation and has no commercial experiance to my knowledge.

Are you sure that USDA has experts for BSE testing?

You could almost get the feeling they are deliberately skipping over Prionics for the least supperior TSE rapid test. I believe the Canadians finally did choose prionics. maybe paul or marcus might comment?

The Prionics western blot test is also a good rapid test which of course does not produce false positive results. In addition this test allows to see new variants of BSE, which would not be seen with the BioRad. But at least in Europe its positive results become confirmed by the OIE Western blot exactly as the BioRad results. Because of this control step the BioRad test cannot produce significantly more problems.

seems if North America is going to be a consolidated BEEF trading market amongst themselves and expect to export there tainted products everywhere, they could at least come up with the same TSE rapid Test. how can one use a less reliable test and the other use a more reliable test, and it all be the same? i know there is a word Dehaven used, but it slips my mind now, (consolidated markets) that's not it, but you get the just of my thoughts, i think;-)...TSS

Not the minor differences between the rapid tests are the problem, but the much to low testing numbers and the prefered IHC-testing in the USA. In Germany we test every month as many as the USA is going to test per year (mostly with BioRad) - and we have only 13 million cattle.

kind regards

Roland

########### http://mailhost.rz.uni-karlsruhe.de/warc/bse-l.html ############

-------- Original Message -------- 
Subject: Re: US CHOICE OF MAD COW TEST QUESTIONED 
Date: Thu, 25 Mar 2004 02:51:09 +0100 
From: Moser Markus 
Reply-To: Bovine Spongiform Encephalopathy 
To: [email protected]

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

Dear Roland Immunohistochemistry, correctly executed, is the gold standard, together with the OIE Western blotting method. It allows detection of infection even in cases where prion aggregates can only be detected in few individual cells. It is certainly not less sensitive than either Bio-Rad or Prionics. In fact, the abundant data on all three methods indicate equal diagnostic sensitivity (if sampling is done appropriate: note that immunohistochemistry has to be conducted on different tissue samples, since the tissue has to be formalin fixed). In case a BSE case obtained with a rapid test cannot be confirmed in a first approach with one of the gold standard methods, the second method will be used. I agree, that the sensitivity of immunohistochemistry can be negatively influenced e.g. by only looking at a limited number of slides or by not carefully examining the slides for prion aggregates. However, if a rapid test is not confirmed by immunohistochemistry due to a sloppy analysis, it will still show up in the OIE Western blot. Nevertheless, it is of course possible, that a true positive result cannot be confirmed e.g. if only the tissue sample used for the initial testing contained prion aggregates, which is theoretically possible, since the aggregates are not evenly distributed in the tissue. This is why it is not formally possible to disproof with 100% certainty an initial positive diagnosis (and you are right: it's certainly wise to rather not eat any suspicious animals). Nevertheless, false positives cannot in general be attributed to faulty confirmatory tests, but to the fact that the ELISA method simply produces a certain rate of false positives, which is why we offer rapid BSE tests on both platforms, the ELISA and the Western technology. And we make it clear to our customers, that when choosing the Prionics-Check LIA (the ELISA based test) coping with occasional false positive results will be inevitable. The LIA is therefore mostly used in European countries, with well established levels of BSE, while the Prionics-Check Western is also used in BSE-free countries (where a maximum positive predictive value is important to support the conclusion of low frequency or absence of BSE, which would otherwise be difficult for the reason you indicated and I mentioned above, i.e. due to the reason that it is hard to formally disprove an initial diagnosis with absolute certainty). Regards, Markus

-------- Original Message -------- 
Subject: Re: ''INCONCLUSIVE'' IS NEGATIVE or so they claim...OFFICIAL REPORT 
Date: Tue, 1 Feb 2005 16:59:27 -0600 
From: "Terry S. Singeltary Sr." 
Reply-To: Bovine Spongiform Encephalopathy

To: [email protected] References: <[email protected]> <[email protected]>

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



Original Message -------- 

Subject: Re: BSE 'INCONCLUSIVE' COW from TEXAS ??? 
Date: Mon, 22 Nov 2004 21:07:51 -0600 
From: "Terry S. Singeltary Sr." 
To: Carla Everett References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> 


ok, thank you Carla. i hate rumors and 'inconclusive' announcements. kind regards, terry Carla Everett wrote: 

> our computer department was working on a place holder we could post 

> USDA's announcement of any results. There are no results to be 

> announced tonight 

> by NVSL, so we are back in a waiting mode and will post the USDA 

> announcement 

> when we hear something. 



> > > At 06:05 PM 11/22/2004, you wrote: 

> >> why was the announcement on your TAHC site removed? 

>> >> Bovine Spongiform Encephalopathy: 

>> November 22: Press Release title here 

>> >> star image More BSE information 

>> >> >> >> terry 


>> >> Carla Everett wrote: no confirmation on the U.S.' inconclusive test... 

>>> no confirmation on location of animal. 


I still want my Texas mad cows confirmed BY WB! TSS



-------- Original Message -------- 
Subject: Re: BSE 'INCONCLUSIVE' COW from TEXAS ??? 
Date: Mon, 22 Nov 2004 21:07:51 -0600 
From: "Terry S. Singeltary Sr." 
To: Carla Everett References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>

ok, thank you Carla. i hate rumors and 'inconclusive' announcements.

kind regards, terry

Carla Everett wrote:

our computer department was working on a place holder we could post USDA's announcement of any results. There are no results to be announced tonight by NVSL, so we are back in a waiting mode and will post the USDA announcement when we hear something.

At 06:05 PM 11/22/2004, you wrote:

why was the announcement on your TAHC site removed?

Bovine Spongiform Encephalopathy: November 22: Press Release title here star image More BSE information

terry

Carla Everett wrote:

no confirmation on the U.S.' inconclusive test... no confirmation on location of animal.

I still want my Texas mad cows confirmed BY WB!

TSS


http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2005/08/0336.xml


http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2005/08/0339.xml


http://www.usda.gov/documents/vs_bse_ihctestvar.pdf


http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2005/06/0217.xml




48 HOUR BSE TEST TURN AROUND TURNS INTO ALMOST A YEAR, from Nov. 2004 when Texas TAHC first announced BSE postive, then took it back, and then almost one year later, Nov. 2005, a final BSE positive confirmation was announced, after only scientist around the globe, and literally an act of Congress took place by the Honorable Fong order the sample retested. ...Thank YOU!



http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2005/06/0218.xml


http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2005/06/0206.xml



ONE YEAR LATER, finally confirmed $$$


Release No. 0233.05 Contact: USDA Press Office (202) 720-4623

Printable version Email this page

TRANSCRIPT OF MEDIA CONFERENCE WITH REMARKS MADE BY AGRICULTURE SECRETARY MIKE JOHANNS, DR. JOHN CLIFFORD, CHIEF VETERINARY OFFICER, ANIMAL PLANT HEALTH INSPECTION SERVICE, AND DR. DANNY MATTHEWS, TSE PROGRAM MANAGER, VETERINARY LABORATORIES AGENCY, WEYBRIDGE, ENGLAND - WASHINGTON D.C. - JUNE 24, 2005


SNIP...



"So let me start first with the test results. As you are aware, last November we had an inconclusive report from a rapid screening test. USDA then conducted two IHC confirmatory tests, and both came out negative. A few weeks ago an additional confirmatory test was conducted, and that test is referred to as the Western blot test.

"On June 10 I learned that test was reactive and shared those results at that time.

"We now have the test results from the lab in Weybridge, England, as well as the results from additional testing in our own lab, and again I am here today to share those results with you.

"The results confirm the presence of BSE in this animal, an animal that was blocked from entering the food supply thanks to the firewalls that are in place. It is critically important to note that this animal was identified as a high risk animal. A sample was taken, and the carcass was incinerated.

http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2005/06/0233.xml



http://madcowtesting.blogspot.com/2008/01/bse-oie-usda.html



Tuesday, July 14, 2009

U.S. Emergency Bovine Spongiform Encephalopathy Response Plan Summary and BSE Red Book Date: February 14, 2000 at 8:56 am PST

WHERE did we go wrong $$$


http://madcowtesting.blogspot.com/2009/07/us-emergency-bovine-spongiform.html




TSS


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