Viruses Not to Blame for Chronic Fatigue Syndrome

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A scientific controversy appears to have been put to rest. At the behest of the National Institutes of Health (NIH), researchers conducted a study of 293 people and found no link between chronic fatigue syndrome and retroviruses.

The debate dates back to 2009, when a since-retracted paper in the journal Science reported a possible connection between the retrovirus XMRV — a common mouse virus — and chronic fatigue, a disabling condition that causes memory impairment, concentration problems, muscle weakness, joint pain and persistent fatigue. A separate study published the following year linked the illness with another mouse retrovirus known as pMLV.

The potential for a viral cause of chronic fatigue caused a stir in the medical community — and offered hope to millions of sufferers who say their symptoms are not taken seriously by doctors — but when numerous other scientists tried to replicate the results of the initial research, they failed. The early findings are now attributed to lab contamination of the blood samples used in the original study. Science retracted the 2009 paper in December.

(MORE: The Chronic Fatigue Retraction: Good Science Takes Time)

Still, some chronic fatigue researchers and many affected patients did not consider the controversy resolved. So the NIH asked virologist Dr. Ian Lipkin of Columbia University to get conclusive answers. “We went ahead and set up a study to test this thing once and for all and determine whether we could find footprints of these viruses in people with chronic fatigue syndrome or in healthy controls,” Lipkin said in a statement. “The bottom line is we found no evidence of infection with XMRV and pMLV. These results refute any correlation between these agents and disease.”

The researchers examined nearly 300 people in the study, about half of whom had chronic fatigue syndrome and half did not. They drew blood from the participants and tested the samples for genes specific to the XMRV and pMLV viruses. This was similar to how the previously studies were conducted, but unlike the earlier studies, the researchers took care to eliminate contamination of the enzym mixtures and chemicals used during testing, which may have been the source of the contamination in the initial research. The scientists reported that they did not find any trace of the retroviruses in the blood samples.

(MORE: Scientists Back Down From Viral Cause of Chronic Fatigue Syndrome)

Several of the authors of the original research collaborated on the new study, published online in the journal mBio. As the Wall Street Journal reported:

Judy Mikovits, who led the 2009 XMRV study and is an author of the mBio paper, said that although the recent effort found no association of the viruses with chronic fatigue syndrome, it helped develop a collection of CFS samples never before available to investigators, which would advance study of the disease.

“We are not abandoning the patients. We are not abandoning the science. The controversy brought a new focus that will drive efforts to understand [chronic fatigue syndrome] and lead to improvements in diagnosis, prevention and treatment of this syndrome,” said Lipkin in the statement. About 1 to 4 million Americans may suffer from chronic fatigue, according to the Centers for Disease Control and Prevention (CDC), and treating the disease costs the U.S. about $7 billion each year.