Chronic Fatigue Not Tied to Mouse Virus in Repudiation of Earlier Findings

Nine U.S. laboratories were unable to confirm early reports that chronic fatigue syndrome stems from infection with a newly discovered mouse virus, including researchers at the facilities that first raised the possibility.

The authors of the first study in 2009 linking the virus known as XMRV to chronic fatigue syndrome also retracted a portion of the findings, saying DNA samples they received were contaminated before they reached the laboratory. The study and the partial retraction were released today online in a publication of the journal Science.

The results add to evidence that chronic fatigue isn’t caused by XMRV or related viruses and show the nation’s blood supply shouldn’t be routinely tested for them, the researchers said. Newly designed laboratory tests for novel viruses should be thoroughly evaluated before they are widely used, said senior author Michael Busch from the Blood Systems Research Institute and the University of California, San Francisco.

“There is no question several of the lab tests represented in the study are flawed,” Busch said in a telephone interview. “They are calling positive results somewhat randomly in patients and healthy donors.”

Researchers took blood from 15 people who previously tested positive for XMRV or a related virus known as P-MLV, including 14 with chronic fatigue syndrome. Blood was taken from another 15 people with no signs of either virus. The samples were divided into numerous vials and sent to laboratories including those run by the U.S. Centers for Disease Control and Prevention, the Food and Drug Administration, the Whittemore Peterson Institute, Abbott Laboratories and Gen-Probe Inc.

Negative Findings

Seven of the laboratories were unable to detect any sign of the viruses. The two laboratories that generated positive results found the virus in samples taken from patients with previous signs of infection and no previous signs of infection. In several cases, they found the virus in one sample of blood taken from a donor and not in a separate sample taken from the same person.

The study was funded by the U.S. Department of Health and Human Services. Another study testing blood taken from 150 people with chronic fatigue and 150 without the condition is under way. Those results are expected by the end of the year.

The original study led the American Red Cross, the largest U.S. supplier of blood products, in December 2010 to ban blood donations from sufferers of the disease.

‘No Threat’

“The results of this study, along with other recent findings, reassure us that these viruses do not pose a threat to the safety of the nation’s blood supply,” said Susan B. Shurin, acting director of the National Heart, Lung and Blood Institute. “These data add to the mounting evidence that there is no need to screen blood donors for them at the present time.”

More than 1 million people in the U.S. have chronic fatigue syndrome, more than those with multiple sclerosis, lupus, or lung cancer, according to the Atlanta-based CDC. The condition, which saps people of energy for months or years, has no proven cause and mostly affects women ages 30 to 50, according to the National Institutes of Health. Women are four times more likely than men to develop the disease.

To contact the reporter on this story: Michelle Fay Cortez in Minneapolis at mcortez@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net.

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