The virus known as XMRV does not cause chronic fatigue syndrome.
Achieving this particular bit of knowledge has taken a pretty spectacular couple of years.
In October 2009, Judy Mikovits, a scientist then at the Whittemore Peterson Institute in Reno, Nevada, and her colleagues published a startling paper. They found that 68 out of 101 people suffering from chronic fatigue syndrome (also known as myalgic encephalomyelitis) carried a virus called XMRV. Only 8 out of 218 healthy people had it. That’s 67% versus 3.7%. Mikovits and her colleagues raised the possibility that the virus played a part in the disorder, which affects an estimated 60 million people. If that were true, then there might be a straightforward way to treat people: wipe out the offending virus.
Very quickly, a number of other scientists replicated the experiment. One team found evdience of a different virus in some of their subjects–not XMRV. The other scientists couldn’t find any virus at all that was present in any significant number of people with chronic fatigue and not in people without it.
With remarkable speed, the study and the follow-up research gave rise to a fierce controversy. Critics dismissed Mikovits’s work as nothing more than contamination (the virus is …