WASHINGTON — Two new studies say a link between a virus and chronic fatigue syndrome probably was a false alarm, the latest possible culprit that could fall by the wayside.
In 2009, a group of researchers in Nevada and Maryland announced they’d found traces of a mouse-related virus named XMRV in the blood of a number of chronic fatigue patients. The headline-making discovery fuelled hope that perhaps a cause had finally been found for the mysterious illness thought to afflict about one million Americans. The virus also was found in certain prostate tumours.
But doubt was growing among independent researchers as numerous other studies failed to find any connection between the purported infection and human illness.
Tuesday, the journal Science took the unusual step of declaring the XMRV link “seriously in question” — as it published research that concluded the earlier connection almost certainly was the result of laboratory contamination.
Sophisticated genetic tracing from the National Cancer Institute found the XMRV virus itself arose from the combination of two other mouse viruses during some experiments about a decade ago that involved growing human prostate tumours in the animals. The virus’ genetic fingerprint so closely matches what was later found in samples taken from patients that it’s extremely unlikely the XMRV could have come from another source than contamination in laboratories, the researchers concluded.
In a separate study, yet another team of researchers tested blood from the same chronic fatigue patients used to make that first 2009 link with XMRV. This new testing, which avoided using lab products derived from mice, found no evidence XMRV, further supporting the lab-contamination explanation.