Study casts more doubt on virus, chronic fatigue link

WASHINGTON -- There's more evidence that a virus once thought to be linked to chronic fatigue syndrome was a false alarm. A study released Thursday concluded lab tests used to make that link are unreliable.

The journal Science also said Thursday that researchers were withdrawing part of the original study that suggested the connection -- although not its conclusions -- because a laboratory that contributed to the work discovered contamination in some of its samples.

In 2009, Nevada researchers announced they had found a mouse-related virus named XMRV in the blood of chronic fatigue patients, fueling hopes that a cause of the mysterious illness might have been found.

Blood banks began turning away donations from people diagnosed with chronic fatigue. Yet numerous other studies failed to confirm the findings. Last spring, Science declared any link "seriously in question" as genetic tracing suggested it was the result of laboratory contamination.

The newest study, also reported in Science, was part of government efforts to see if XMRV or related viruses might affect the safety of the blood supply. It concluded there's no reason to worry.