(Following the Oct. 8 publication by Lombardi et al in Science linking CFS and xenotropic murine-related retrovirus (XMRV), the CFIDS Association of America requested guidance from the National Cancer Institute about XMRV for persons diagnosed with CFS, their loved ones, and the general public. The following are interim guidelines excerpted from a letter received from NCI director Dr. John E. Niederhuber.)
We at the National Cancer Institute (NCI) have great interest in these initial research findings. At present, we agree that a critical issue to be addressed is whether the exciting recent results obtained using samples from the Nevada cohort can be reproduced in additional cohorts of CFS-afflicted individuals. The NCI is striving to develop tools so that the general prevalence of XMRV in the population can be ascertained, and the association of XMRV with disease can be examined.
In the meantime, it is very important to reiterate what we do not know at this point, specifically:
- We do not know whether XMRV is a causative agent for CFS, prostate cancer, or any other disease. Even if a causal association can be established, it may be only one of many causes, and there may be other factors, genetic or environmental, that determine the outcome of infection. At the moment, there is no evidence of CFS transmission between family members, even though XMRV appears to be an infectious agent. Thus, it is unclear whether XMRV alone underlies CFS.
- We do not know how XMRV is transmitted from individual to individual. Recent suggestions of sexual or salivary transmission are not based on direct evidence, and conclusions regarding transmission are not credible at this point. Given the frequent isolation of virus from white blood cells, blood-borne transmission is a real possibility, and, while we are not in a position to establish firm guidelines, prudence would dictate that potentially infected individuals refrain from blood donation at this time.
- We do not know how many apparently healthy individuals are infected, and what the distribution of infection is within the U.S. and in the worldwide population. The National Cancer Institute is involved in coordinating a global effort to study these issues.
It is very important to keep in mind that there is no evidence for a new increasing or spreading XMRV infection. Further, no credible evidence exists for direct transmission of either CFS or prostate cancer.
John E. Niederhuber, M.D.
Director, National Cancer Institute
U.S. National Institutes of Health
Department of Health and Human Services
October 23, 2009
Note from Dr. T: As people with CFS already have been shown to have low blood volumes (despite tests showing normal blood counts), it is best not to donate blood anyway if you have CFS. In seeing over 3,000 CFS patients in the last 20 years, wife to husband transmission seems rare, as does coming down with CFS after blood transfusion.