A study that doctors and patients alike pinned their hopes on has not been conclusive in finding a linked between the Chronic Fatigue Syndrome and a virus known as XMRV, which includes a group in a class of mouse leukemia.

Two different researchers had reported a link between Chronic Fatigue and murine leukemia, but new studies have been not able to confirm the findings, leading scientists to conclude that perhaps samples or equipment were contaminated.

Samples were sent out to nine separate laboratories in a blind study that hoped to detect the XMRV virus, however only two labs were able to report positive results, which does not conclusively reproduce the previous findings.

The new study, written by researchers participating in the Blood XMRV Scientific Working Group, reported that :

“These results indicate that current assays do not reproducibly detect XMRV/M.L.V. in blood samples and that blood donor screening is not warranted.”

Adding to the confusion, researchers who produced the original reports retracted a portion of their data released in Science Magazine in 2009. They still stand by their results, but new evidence of contamination has come to light.

Vincent Racaniello, a microbiology professor at Columbia University who has covered the controversy on his popular virology blog, said the XMRV/M.L.V. hypothesis was now dead.

Racaniello said:

“It’s clearly time to move on in the study for
the origin of this disease.”

It is estimated that more than one million Americans suffer from chronic fatigue, and while countless studies have found immunological, neurological and physiological abnormalities, patients report that their symptoms are not exactly a question of fatigue, but more a problem of excessive depletion of energy after only a small amount of activity.

Some of the leading researchers in the field have put forward an enhanced definition that requires the presence of postexertional exhaustion, rather than the six months of unexplained tiredness that is currently the standard and they also recommended using the name myalgic encephalomyelitis, which is already recognized by the World Health Organisation (WHO).

Dr. Nancy Klimas, an immunologist at the University of Miami, said that the two-year debate over M.L.V.’s had raised the profile of the disease and brought attention to the likely role of infectious agents in chronic fatigue syndrome, writing that:

“Internationally recognized experts have looked at the immune data and concluded that there very well may be a pathogen or pathogens involved in the persistence of this illness.”

International Association for Chronic Fatigue Syndrome/ME will be presenting the findings today (Friday) at their conference in Ottawa.

Rupert Shepherd BSc. Reporting For Medical News Today