In this study, researchers did PCR testing on 186 people in England suffering with CFS and found that none of them was positive for the XMRV virus. So how does one make sense of this conflicting information?
There are several probable answers to what is occurring:
It could simply be that the testing methods used in the second study were not reliable. This is the impression of the folks at the WPI, where the initial study was done, and in a press release the WPI comments on the new study. In addition, Suzanne Vernon, scientific director of the CFIDS Association of America, has offered her insights in a recent press release.
This is not an unlikely scenario, as testing done at the WPI was much more complex and I suspect more likely to be accurate.
XMRV virus may simply be more common in people in the United States and rare in Europe. This was supported by the four studies done on XMRV and prostate cancer. The two done in the United States showed a surprisingly high prevalence of the virus in prostate cancer patients while the two European studies did not find the virus to be present.
Questions have been raised about the patients used in both studies.
One of the main researchers in the England study is Dr. Simon Wessely, a nice and very bright fellow who I suspect is so blinded by his determination to have CFS viewed as a psychological disease requiring only counseling that I find most of his research to have a decidedly unhealthy bias. I think if he applied his same bias to patients dying of lung cancer, he would also see them as being “not really sick” (i.e., he would see them as crazy). On the other hand, I have enjoyed the work of Anthony Cleare on HPA axis/adrenal issues in CFS over the years. I find it interesting that they have teamed up on a number of studies recently — including this one.
The source of the WPI study patients, based on the paper, is also not clear to me. My main concern is that they not come largely from a single epidemic of CFS, such as the Tahoe group, as this could largely skew the results. Again, we look forward to seeing the results of testing of patients from around the country (and indeed around the world) to see what percentage are positive.
For those setting up studies looking for XMRV in CFS patients, the above study suggests a simple way to answer these questions if they arise again. As a medical reviewer, it would be very helpful if the studies sent all or even 10-20% of their blood samples to the WPI for testing, while also doing the testing in their own labs. Half of the samples sent to the WPI should be from healthy patients, and the samples should be blinded (i.e., not labeled as to whether they are coming from CFS or healthy control patients). If the samples sent to the WPI clearly again come up positive for CFS and negative for healthy patients, as in the earlier study, it would immediately answer the question of whether there is a methodology problem and it would quickly answer many of our questions. So in real life, there is really a very simple approach that could answer these questions.