New research has further undermined an already widely questioned supposed link between a virus and chronic fatigue syndrome.
Between 1 million and 4 million Americans are thought to have chronic fatigue syndrome, a mysterious disorder that causes prolonged and severe fatigue, body aches and other symptoms.
In 2009, a team of scientists in Nevada reported finding evidence of a virus known as the xenotrophic murine leukemia virus-related virus (XMRV) in the blood of patients with the disorder. That generated excitement that a cause may have finally been found, and prompted the American Red Cross to bar chronic fatigue patients from donating blood.
But subsequent studies aimed at confirming the findings have produced mixed results, with most failing to duplicate the findings. In June, two research teams reported that the virus was a laboratory contaminant incapable of infecting human blood.
In the new research, published online Thursday by the journal Science, researchers at nine different laboratories, including the authors of the original report, analyzed blood samples form 15 people previously reported to be infected with XMRV or a related virus and 15 healthy people. Only two of the labs found the virus in the supposedly infected individuals and both also found the virus in the healthy people and produced conflicting results.
In addition, in a separate “partial retraction” to the original report also published online by Science, two of the authors of the original study said they reexamined the samples they had used for one type of testing and concluded the samples had been contaminated.
Advocates for patients with the syndrome were disappointed.
“We share the deep disappointment of many CFS patients and scientists that the initial data did not hold up. Whether you have been diagnosed recently or have been ill for decades, this news comes as a blow to hope for rapid advances in the care available to CFS patients,” said Kim McCleary of the CFIDS Association of American in a statement.
“The urgent need for better diagnostics and treatments must be met. We’re determined to translate the heightened attention and deeper engagement XMRV has attracted into sustainable progress,” McCleary said. “There are many other solid leads that merit the same rigorous follow-up as XMRV has received over the past two years.”
In a statement, Vincent Lombari of the Whittemore Peterson Institute in Reno, Nev., said that while researchers at the institute “will be participating in supporting the partial retraction ...we want to make it very clear that we are continuing the important work of studying retroviruses in association with” chronic fatigue syndrome “and other similarly complex illnesses.”
This post has been updated since it was first published.