Chronic Fatigue Syndrome Linked to Virus Obscure virus found in two-thirds of sufferers By Rob Quinn, Newser Staff Posted Oct 9, 2009 6:45 AM CDT 14 comments Comments "We now have compelling proof that a retrovirus named XMRV is present in more than two-thirds of patient samples with chronic fatigue syndrome," the lead researcher said. (Shutter Stock) (Newser) – A research team believes it has finally uncovered the cause of chronic fatigue syndrome. The mysterious syndrome—labeled "yuppie flu" in the '80s and considered by some doctors to be a purely psychiatric problem—appears to be caused by an obscure retrovirus, the scientists say. Some 67% of sufferers carried the virus, and 95% had antibodies for it, their research found, compared to just 4% in a control group. "With those numbers, I would say yes, we've found the cause of chronic fatigue syndrome," said the lead researcher. "We also have data showing that the virus attacks the human immune system." The team plans to test the effects of anti-retroviral drugs in sufferers. Other experts say the study was too small to be conclusive. "It's spectacular but needs replication," one prof tells the Independent.