LONDON, Dec. 21 (UPI) -- Researchers at the University College London say chronic fatigue syndrome is not caused by the virus XMRV, but it may be caused by another virus.
Greg Towers says XMRV was first linked to chronic fatigue syndrome -- myalgic encephalomyelitis -- in a study published in October 2009, in which blood samples from chronic fatigue syndrome patients were found to have traces of the virus.
The virus has also been identified in samples from certain prostate cancer patients.
The new study, published in Retrovirology, identifies the source of XMRV in chronic fatigue syndrome samples as being cells or mouse DNA, rather than infection by XMRV. The research does not rule out a virus cause of chronic fatigue syndrome, but it does rule out the XMRV virus.
"Our conclusion is quite simple: XMRV is not the cause of chronic fatigue syndrome," Towers says in a statement. "It is vital to understand that we are not saying chronic fatigue syndrome does not have a virus cause – we cannot answer that yet – but we know it is not this virus causing it."