Virus may be culprit of chronic fatigue: Study understood, published, sometimes, physical, question

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Virus may be culprit of chronic fatigue: Study


OTTAWA — Could a virus be the cause of the poorly understood illness known as chronic fatigue syndrome? That question has been hotly debated by researchers since 2009, when a study published in the prestigious journal Science suggested that a little-known virus called XMRV might be the culprit.

Patients saw the study as vindication for an illness that has sometimes been stigmatized as more mental than physical. Top infectious-disease experts began investigating more closely.

And, in a precautionary move to protect the blood supply from a potential new contaminant, the Red Cross and Canadian Blood Services stopped accepting donations from people diagnosed with chronic fatigue syndrome.

Last week, an eagerly awaited study co-ordinated by the U.S. government found no link between the disease and XMRV.

The new multi-lab study, published online in Science and presented in Ottawa at an international conference on chronic fatigue syndrome, was designed to answer some of the questions about these unusual viruses and determine whether they posed a risk to the blood supply.

Of the nine labs that received blinded blood samples from 15 people previously reported to have been infected with XMRV and 15 healthy controls, only two reported finding evidence of the viruses in any of the samples.

Because the study only looked at a small sample of patients, some experts say they are reserving judgment until results from another U.S.-sponsored study, with a much larger sample size, are published next year.

“I think we need a larger study before we absolutely rule it out,” said Dr. Nancy Klimas, an immunologist at the University of Miami.

The new findings also don’t rule out the possibility that other viral infections could play a central role, said Fred Friedberg, president of the International Association for Chronic Fatigue Syndrome, which is hosting the Ottawa conference this weekend.

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“One reason is the illness presents with flu-like symptoms so you would think it would be a virus. That’s what many patients think. That’s what many physicians think. It’s just that the virus has not been uncovered.”

Since the first cases were identified in the 1980s, chronic fatigue syndrome has been a medical mystery and subject of sometimes bitter debate. Some employers and insurers have dismissed the condition as stress-related, psychosomatic or simply imaginary.

The ailment affects more than 333,000 Canadians, according to Statistics Canada, and causes months, even years of unending flu-like symptoms: profound exhaustion, sleep problems, muscle and joint pain, severe cognitive problems.

Countless studies have documented immunological, neurological and physiological abnormalities in patients with the disorder, including the reactivation of dormant viruses such as measles or mononucleosis.

More recently, researchers have documented not only simple fatigue, but also a dramatic overreaction by the body’s immune system, leading to a cascade of inflammation in patients who do even a light amount of exercise, but don’t have any signs of infection.

“What we’re saying is the immune system is damaged,” said Klimas.

“We don’t know why. And viruses seem to reactivate and help perpetuate the illness, with the inflammatory responses making patients feel very ill.”


Klimas said even if XMRV is determined not to be the cause of chronic fatigue syndrome, the two-year debate has raised the profile of disease and drawn attention to the likely role played by infectious agents.

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Since the first cases were identified in the 1980s, chronic fatigue syndrome has been a medical mystery and subject of sometimes bitter debate. Some employers and insurers have dismissed the condition as stress-related, psychosomatic or simply imaginary