A theory that a virus is the culprit for the mysterious chronic fatigue syndrome has just suffered another serious blow. But some patient advocates are standing by it, saying more research is needed.
Researchers from nine different labs looked for the XMRV virus in the blood of 15 people with the condition and 15 healthy people. Only two labs found the virus, and even then, they found it at the same rate in the patients as in the healthy folks. The study appears in the online version of the journal Science.
Chronic fatigue syndrome is by all accounts a difficult illness – there's no known cause and consequently no test to detect it. There's also no cure. People can suffer the intermittent bouts of crushing fatigue and pain for a few months or for decades. One woman in Seattle who says she's had it for two decades went 15 months without having a "good" day.
Many causes have been suggested over the years, including the virus that causes mononucleosis, a member of the herpes virus family, and a bacterium or two. All of them were eventually shot down. That it's been so difficult to ferret out the cause is discouraging for patients since finding a culpable microbe would help make a diagnosis and suggest ways to treat the condition.
In 2009, hope came in the form of XMRV, a retrovirus originally found in mice. In a study, researchers looked at 101 people with chronic fatigue syndrome, and 218 healthy people. They found the virus in 67 percent of the patients, compared to 4 percent of the others.
But XMRV's status has been short-lived. This past May, two studies quashed the initial link, and said the virus was a laboratory contaminant.
Now there's the new report, with 23 authors, including some of the original researchers from the hopeful 2009 study. One of the other authors is Anthony Komaroff, professor of medicine at Harvard University.
He says the XMRV claim is on "very shaky ground. There does not appear to be an association between mouse retroviruses and chronic fatigue syndrome."
Also in this week's issue of Science, the authors of the original 2009 study partially retracted their findings, saying one of the three tests they used did not yield accurate results.
And Kim McCleary, head of the CFIDS Association, an advocacy group for people with chronic fatigue syndrome, says it's time to look for something else. "There are many other solid leads that merit the same rigorous follow-up as XMRV has received over the past two years," she says.
But some of the original authors are not backing down. The Whittemore Peterson Institute released a statement saying its initial work "continues to warrant additional investigations." And Judy Mikovits, the lead researcher at the institute, told two reporters from the news section of Science that maybe the virus is hiding in tissue, or maybe it's different from what they thought it was. "I'm not going to stop studying it," she told them.
Meanwhile, a lab at Columbia University is going to give one more go at XMRV. You can follow the studies at Research1st, the research arm of CFIDS.