Chronic Fatigue Syndrome: Names and Claims

By Robert H. Shmerling
By Robert Shmerling, M.D.
Content provided by the Faculty of the Harvard Medical School

I first learned about Chronic Fatigue Syndrome (CFS) from a popular magazine that called it "Yuppie flu." I should have looked for better sources of medical information, because that term clouded my view of the condition for years. And I wasn't the only one.

A number of misconceptions and much speculation surround this mysterious disorder. Here are a few of the most common. Each is currently either unproven or untrue. But that could change over time. So, rather than calling them "myths," let's call them "claims."

Claim #1: There is no set definition of CFS

This used to be true. But in 1994 the U.S. Centers for Disease Control and Prevention (CDC) and other international experts developed criteria to help define the condition partly to be reasonably confident that different researchers were studying the same disease. Practicing physicians may not routinely use these criteria in diagnosing an individual patient, but they are still the best definition of the condition we have.

Besides persistent unexplained fatigue that is severe enough to impair activity, the diagnosis requires at least four of the following symptoms:

  • Poor memory or reduced concentration

  • Sore throat

  • Sore lymph nodes in the neck or under the arms

  • Pain in the muscles

  • Joint pain, without evidence of swelling or warmth

  • Headaches (either increasing in severity or of recent onset)

  • Need for more sleep despite getting plenty of sleep

  • Feeling unwell for a day or more after physical activity

Claim #2: CFS is a new disease

Actually, conditions with symptoms strikingly similar to CFS go back at least several hundred years, although they went by different names. For example, it the mid-1700s, a condition called "Febricula" (little fever) was popular, while in the 1870s, a similar disorder was called "DaCosta's syndrome" (named for the American internist who described "utter fatigue with effort"). At the turn of the last century, "neurasthenia" was the accepted name, while "myalgic encephalitis," "Iceland disease," and "Royal Free disease" were used in different parts of the 1900s in different parts of the world. Names based on presumed causes were also common, including:

  • Chronic brucellosis — Brucella is a bacteria that can be transmitted to humans from cattle, most commonly through unpasteurized milk; symptoms include fever and fatigue; the connection between brucella infection and CFS was popular in the 1930s to 1950s but has since been discounted

  • Hypoglycemia — Low blood sugar was thought to be a common cause of fatigue, including CFS during the 1950s to 1970s

  • Chronic Epstein-Barr Virus (EBV) — The virus that causes mononucleosis was thought to persist in the body

  • Multiple Chemical Sensitivity Syndrome — Many people (and some physicians) believe that extensive allergies or reactions to minute amounts of chemicals in the air or by contact may cause a CFS-like illness

  • Chronic candidiasis (or chronic yeast infection)

Claim #3: CFS is due to an infection

As the names above suggest, infection has long been considered a possible cause of CFS. This hasn't been proven, but it's understandable that an infection — one that the immune system cannot completely eliminate — would be the prime suspect. Part of the appeal of this theory is that CFS can begin suddenly in a previously healthy person, much the way that the flu or other severe, acute infections begin.

There are many infectious diseases that cause prominent fatigue for prolonged periods: mononucleosis, hepatitis B and C are good examples. However, despite extensive research to identify an infectious cause, there is no conclusive evidence that CFS is an infectious illness.

Even so, that does not rule out the possibility that a chronic infection (or the "fallout" from an infection) is to blame. In fact, recent research has focused on a herpes virus (called HHV-6), a common viral cause of rash and fever in infants and young children. Because most adults (95%) have been infected with this virus during childhood and because it can persist in the body for many years, it should not be surprising that this virus would be a focus of study for CFS researchers. Perhaps the virus is contained enough by the body to prevent damage to vital organs. But its persistence in the body might cause symptoms of low grade fever, fatigue and the other symptoms of CFS.

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