Sept. 13, 2007 - A group of viruses known to cause respiratory and gut infections may also be a major trigger for chronic fatigue syndrome (CFS).
Enteroviruses are very common, second only to the common cold viruses as the most common viral infections in humans, according to the CDC. Most people who are infected with an enterovirus have no symptoms at all.
California infectious disease specialist John Chia, MD, says his findings point to chronic infection with the virus as a possible cause of chronic fatigue syndrome in a large percentage of patients.
But a longtime CFS researcher says the complex disorder is not likely to be so easily explained.
James Jones, MD, of the CDC’s chronic viral diseases branch, says despite extensive research, no cause-and-effect relationship between an active infectious agent and chronic fatigue syndrome has been established.
“This is an illness with a lot of different origins, and to assume that its cause is due to an infection because the symptoms are similar to an infection is a great leap,” Jones tells WebMD.
2.5% of Americans Have CFS
Early this summer, CDC researchers reported that the prevalence of chronic fatigue syndrome may be between six and 10 times higher in the U.S. than previously believed.
The major symptom of the disease is severe fatigue -- not relieved with rest -- that persists for at least six months. But patients also often complain of symptoms such as muscle and joint pain, memory and concentration problems, depression, sleep problems, headaches, sore throat, swollen lymph nodes, and/or gastrointestinal problems.
Chia, who practices medicine in Torrance, Calif., says he began researching chronic fatigue syndrome soon after his son Andrew became sick with the condition in 1997 at age 14.
“It took us a year to find out what he had,” he says.
Early efforts to find a cause for CFS focused on viruses. Jones was among the first to suggest that chronic infection with the virus that causes mononucleosis, the Epstein-Barr virus, might explain the disease.
But the failure to find persistent evidence of Epstein-Barr or any other virus in the blood of CFS patients led most researchers, including Jones, to look elsewhere for causes.
The lack of a diagnostic test for chronic fatigue syndrome also led many to dismiss it as an imaginary disorder, but recent research by CDC and others have proven that it is both real and common.
Other Conditions Lead to CFS
In previous research, Chia reported finding evidence of chronic infection in the muscles of CFS patients.
In the new study, he looked for similar evidence in stomach tissue taken from CFS patients who had the diagnostic procedure known as endoscopy, in which a long tube with a camera is inserted via the mouth into the stomach and biopsies of tissue are taken.
Specimens from 165 CFS patients and 34 people without the disorder were tested, and Chia found evidence of possible chronic infection in 82% of the CFS patients and 20% of the well patients.
Though the findings must be verified, Chia says they suggest a strong association between possible chronic infection with enterovirus and chronic fatigue syndrome.
“Although finding a chronic infection in the stomach may not directly prove a similar infection in the brain, muscle, or heart, it opens up a new direction in the research for this elusive disease,” he writes in the latest online edition of the Journal of Clinical Pathology.
Specifically, he says endoscopy could prove to be a relatively simple test to confirm persistence of enterovirus infection in CFS patients, as well as a way of following responses to antiviral treatments.
Chronic Fatigue and Immune Disorder Syndrome Association of America president Kimberly McCleary says CFS has turned out to be a much more complex illness than anyone could have predicted.
“It is unlikely that we are ever going to find just one bug to explain all cases of CFS,” she says.
She points to recent research from Australia finding that three very different infections result in a CFS-like condition in 12% of cases.
“It is quite possible that both an infectious agent and the [body’s] response to that agent act as triggers,” she says.