Virus Disproved as Cause of Chronic Fatigue Syndrome, National Institutes of Health (NIH) Study

Chronic fatigue syndrome is not caused by a mouse retrovirus, according to a study initiated by the National Institutes of Health to settle what had become a contentious scientific question. The long-awaited results, posted online Tuesday in the journal mBio, found no link between the illness, also called myalgic encephalomyelitis, and mouse leukemia retroviruses, including one called XMRV. Two earlier studies had identified higher levels of the viruses in patients with chronic fatigue syndrome. Later research did not confirm the finding, and scientists blamed laboratory contamination for the earlier results.