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.... about the 20 samples that WPI sent for testing to the CDC. WPI found all 20 to be positive; CDC found all 20 to be negative.
CFS Central
http://www.cfscentral.com
CFS Central
http://www.cfscentral.com
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CDC RESPONDS TO THE QUESTION, by Mindy Kitei
- Thread starter Mindy Kitei
- Start date
Legally speaking the CDC may want to alter that statement as the WPI lawyers could consider:
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It brings the WPI into disrepute, and SCIENCE who published their study. Do SCIENCE publish on imaginary retroviruses?
And CDC's Bill Switzer who confirmed the WPI CFS discovery wasn't contamination.
And the makers of the microscope who took the photos of the XMRV.
And CFS patients who have tested positive for XMRV that the CDC say doesn't exist in a positive WPI sample.
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This is not a good moment in science, or for the American government who allow the CDC to behave in such a way.
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It brings the WPI into disrepute, and SCIENCE who published their study. Do SCIENCE publish on imaginary retroviruses?
And CDC's Bill Switzer who confirmed the WPI CFS discovery wasn't contamination.
And the makers of the microscope who took the photos of the XMRV.
And CFS patients who have tested positive for XMRV that the CDC say doesn't exist in a positive WPI sample.
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This is not a good moment in science, or for the American government who allow the CDC to behave in such a way.
Great idea 
.. maybe the CDC should of used the other government depts for confirmation of the negatives they got from samples which were said to be positive. but of cause they didnt as they are so biased they ALWAYS believe they are correct and dont want to believe CFS/ME exists.
.. maybe the CDC should of used the other government depts for confirmation of the negatives they got from samples which were said to be positive. but of cause they didnt as they are so biased they ALWAYS believe they are correct and dont want to believe CFS/ME exists.
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Which takes us back to the two prostate cancer samples which the CDC found positive. Is this the only evidence they have of ability to find virus in infected humans? Current reported rates in that field range from 0% to 33%. A 1% rate of false positives would not be surprising. (Did the 163 other prostate cancer patients suffer from mental problems which caused cancer?) Have they ever found XMRV in human blood without putting it there themselves? What does this say about statistical validity of every number presented in that paper?
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They don't have to. WPI took the precaution of splitting those samples and sending them to other laboratories. Can we guess which laboratories?
that up coming conference is going to be way interesting.. just imagine.. the CDC saying it was sent all false positive samples.. against those who say they werent false.
umm or maybe the CDC has made it up and are actually lying that they tested them, thinking it would be a better way out of the mess??? as after all it would look even worst for them if they said they DIDNT bother to test the samples at all!!! I think saying one did test them and wasnt able to find it, so believed those samples were contamination is the better choice of the two options.
If you were dishonest.. what would you say?
Is the CDC in damage control and telling the best fibs it can to try to escape the mess??? and to look like it really tried. I personally dont trust anything which the CDC says.
This statement is the most logical thing if one is dishonest, to say in this situation.
umm or maybe the CDC has made it up and are actually lying that they tested them, thinking it would be a better way out of the mess??? as after all it would look even worst for them if they said they DIDNT bother to test the samples at all!!! I think saying one did test them and wasnt able to find it, so believed those samples were contamination is the better choice of the two options.
If you were dishonest.. what would you say?
Is the CDC in damage control and telling the best fibs it can to try to escape the mess??? and to look like it really tried. I personally dont trust anything which the CDC says.
This statement is the most logical thing if one is dishonest, to say in this situation.
Great that the WPI did this. But I note that the CDC have said they found the samples negative for antibodies, they still haven't said what their result was for any PCR testing. I thought I saw somewhere that it was Ila Singh's group that also tested the samples and found the majority positive, presumably by PCR. I wonder if Singh's group has done antibody testing on these samples?
Yes, "reaching out"! Sweet, earnest blogger struggles to understand and turns to the great CDC for help. What next, signing off with "kumbaya"? I sense the CDC circling above us now, threatening a group hug. Everybody duck!
Mindy, you're a great, razor-sharp reporter. Thank you for nailing these guys down.
Mindy, you're a great, razor-sharp reporter. Thank you for nailing these guys down.
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laboratories + contamination
That was where one set of samples went, and Singh has not revealed anything about her results, except by planning a much larger study. I was thinking about a different laboratory which has results in press.
Let's go back to that data supporting the reliability of the CDC assay for XMRV, and apply an argument which has surfaced before in these disputes.
First, let me hypothesize a suspicion for which I cannot present any source: the CDC labs have experienced a serious problem with contamination, e.g. by mouse DNA, in the last two or three years.
Second, let's say their rate of detection of XMRV in samples of prostate tissue is around 1%, as shown in a presentation earlier this year.
Third, let's assume they will leave no stone unturned to eliminate contamination if it produces positive results in samples from CFS patients.
Fourth, let's say they will accept positive results in samples from prostate cancer patients, where they expect to find XMRV.
Taken together these make a compelling conjecture that their entire basis for claims of detecting XMRV in infected human beings is due to contamination in a few samples.
This is the kind of argument I was not able to put together w.r.t. the results in the Science paper by Lombardi, et al. Every assumption led to a contradiction. In this case there is no contradiction, and not even a great deal of improbability or implausibility.
Anyone willing to bet against me? :innocent1:
That was where one set of samples went, and Singh has not revealed anything about her results, except by planning a much larger study. I was thinking about a different laboratory which has results in press.
Let's go back to that data supporting the reliability of the CDC assay for XMRV, and apply an argument which has surfaced before in these disputes.
First, let me hypothesize a suspicion for which I cannot present any source: the CDC labs have experienced a serious problem with contamination, e.g. by mouse DNA, in the last two or three years.
Second, let's say their rate of detection of XMRV in samples of prostate tissue is around 1%, as shown in a presentation earlier this year.
Third, let's assume they will leave no stone unturned to eliminate contamination if it produces positive results in samples from CFS patients.
Fourth, let's say they will accept positive results in samples from prostate cancer patients, where they expect to find XMRV.
Taken together these make a compelling conjecture that their entire basis for claims of detecting XMRV in infected human beings is due to contamination in a few samples.
This is the kind of argument I was not able to put together w.r.t. the results in the Science paper by Lombardi, et al. Every assumption led to a contradiction. In this case there is no contradiction, and not even a great deal of improbability or implausibility.
Anyone willing to bet against me? :innocent1:
I agree. Further, the CDC did not mention the 20 negative samples in their study. If they did test them why would they not have said so, even if to twist the knife a little? Either they themselves are aware of how bizarre the 20 negatives look, or they did not really test the samples.
Might have helped if I had read the article first. CDC explains why they didn't mention the samples. Sorry.
Weren't these antibody tests only?
Yes Andrew they were.
The Slide heading was "Absence of XMRV Antibodies in Additional Populations Tested at CDC".
Among other things it listed it said, "0/20 'positive' plasmas from WPI"
That still leaves no PCR result from the CDC for this group. If they got a negative PCR I wonder why they haven't said so?
But at this point maybe the antibody tests might be more important than PCR, as positive results would be evidence that contamination is not present. Given that the reports of the Alter study raised the prospect that MuLV other than XMRV are involved then, if true, this would place a larger onus on positive studies to show that there is no contamination as mice can carry MuLV, unlike XMRV. I am waiting to see what the Alter study has in terms of antibody testing as that might turn out to be pretty important for us.
The Slide heading was "Absence of XMRV Antibodies in Additional Populations Tested at CDC".
Among other things it listed it said, "0/20 'positive' plasmas from WPI"
That still leaves no PCR result from the CDC for this group. If they got a negative PCR I wonder why they haven't said so?
But at this point maybe the antibody tests might be more important than PCR, as positive results would be evidence that contamination is not present. Given that the reports of the Alter study raised the prospect that MuLV other than XMRV are involved then, if true, this would place a larger onus on positive studies to show that there is no contamination as mice can carry MuLV, unlike XMRV. I am waiting to see what the Alter study has in terms of antibody testing as that might turn out to be pretty important for us.
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If the CDC group got positives from PCR testing of those samples, and failed to report this, they have an even bigger controversy on their hands. The least outrageous implication is that they also got 0/20 positives from PCR.
I've been concentrating on PCR because they simply haven't published material in peer-reviewed publications which would allow others to judge the validity of a CDC assay for XMRV infection based on antibodies. Some of the work in the Retrovirology paper raises more questions than it answers. They need other publications to support inferences apparently made there. I'm not even sure some of these are presented as claims, and I don't want to impute false claims to them.
I've been willing to take statements like "0/20 positive" or "2/165 positive" as sufficiently unambiguous to be treated as claims, but I'm not going to go any deeper into the methodology prior to publication.
The validity of the PCR methods rests almost entirely on those control samples produced by the same group which devised the assay. Those other independent laboratories simply validated the methods against controls provided to them. If those controls are not representative of infection by XMRV, there really isn't much validation, independent or otherwise.
The 'spiking' with plasmids, while convenient, rests on an unproven assertion about this being equivalent to having DNA produced by XMRV inside cells. They can cite a number of other groups making this assumption, but none have done the work needed to support the claim. Looking for any evidence the CDC group can detect XMRV in infected humans takes us to those claims in presentations, not to peer-reviewed publications.
Giving the benefit of the doubt in that regard, and (not unreasonably) calling 'spiking' deliberate contamination, leaves the real possibility all positive results from their PCR assay are due to contamination instead of infection. This is not far-fetched.
I'll wait on peer-reviewed publications concerning CDC antibody tests for XMRV before trying to analyze results of that assay.
I've been concentrating on PCR because they simply haven't published material in peer-reviewed publications which would allow others to judge the validity of a CDC assay for XMRV infection based on antibodies. Some of the work in the Retrovirology paper raises more questions than it answers. They need other publications to support inferences apparently made there. I'm not even sure some of these are presented as claims, and I don't want to impute false claims to them.
I've been willing to take statements like "0/20 positive" or "2/165 positive" as sufficiently unambiguous to be treated as claims, but I'm not going to go any deeper into the methodology prior to publication.
The validity of the PCR methods rests almost entirely on those control samples produced by the same group which devised the assay. Those other independent laboratories simply validated the methods against controls provided to them. If those controls are not representative of infection by XMRV, there really isn't much validation, independent or otherwise.
The 'spiking' with plasmids, while convenient, rests on an unproven assertion about this being equivalent to having DNA produced by XMRV inside cells. They can cite a number of other groups making this assumption, but none have done the work needed to support the claim. Looking for any evidence the CDC group can detect XMRV in infected humans takes us to those claims in presentations, not to peer-reviewed publications.
Giving the benefit of the doubt in that regard, and (not unreasonably) calling 'spiking' deliberate contamination, leaves the real possibility all positive results from their PCR assay are due to contamination instead of infection. This is not far-fetched.
I'll wait on peer-reviewed publications concerning CDC antibody tests for XMRV before trying to analyze results of that assay.
I'm too foggy to start writing letters to places right now. But here is a basic point that the CDC response sidesteps.
Checking ones assays against samples found positive by others is a scientific method for double-checking the validity of ones tests. It is not outside the realm of routine publication to include information about validation steps, even if the results call for more testing. By omitting information about these results, they deprive other scientists potentially useful information. They deprive other scientists the opportunity to decide whether the inconsistencies the CDC found need further consideration.
The Centers for Disease Control have a professional and moral obligation to assist in the control of disease. But their actions show only half-hearted attempt to do this. Some might even say this is lying by omission. But either way, they have fallen short of their charter to promote the control of disease. Their lack of full disclosure interferes with other scientists having as much information as possible from which to work. And in making excuses for doing this, the CDC has taken the lower moral ground.
Checking ones assays against samples found positive by others is a scientific method for double-checking the validity of ones tests. It is not outside the realm of routine publication to include information about validation steps, even if the results call for more testing. By omitting information about these results, they deprive other scientists potentially useful information. They deprive other scientists the opportunity to decide whether the inconsistencies the CDC found need further consideration.
The Centers for Disease Control have a professional and moral obligation to assist in the control of disease. But their actions show only half-hearted attempt to do this. Some might even say this is lying by omission. But either way, they have fallen short of their charter to promote the control of disease. Their lack of full disclosure interferes with other scientists having as much information as possible from which to work. And in making excuses for doing this, the CDC has taken the lower moral ground.