Although there is agreement on the genuine threat to health, happiness, and productivity posed by CFS/ME, various physicians' groups, researchers, and patient activists champion very different ideas regarding diagnostic criteria and favored treatments, resulting in ongoing controversy about nearly all aspects of the disorder. The name chronic fatigue syndrome is itself controversial, with some patient advocates and other authorities preferring terms such as myalgic encephalomyelitis ("ME" or "CFS/ME") and post-viral fatigue syndrome ("PVFS"), which imply specific underlying etiologies or pathologic processes.

While fatigue is a common symptom in many illnesses, CFS/ME is a multi-symptom disease and is relatively rare by comparison. Definitions require a number of features, the most common being severe mental and physical exhaustion which is "unrelieved by rest" and may be worsened by even trivial exertion. Most diagnostic criteria insist that the symptoms must be present for at least six months, and all insist on there being no other cause for them: i.e. the symptoms must not caused by other medical conditions such as diabetes, hypothyroidism or anemia. Click here for more information about CFS/ME symptoms.

It is unclear if these symptoms represent co-morbid conditions or are produced by the same underlying etiology as CFS itself. Some cases improve over time, and treatments (though none are universally accepted) bring a degree of improvement to many others, though resolution is rare.

CFS/ME occurs more often, but not exclusively, in women, possibly due to immunological factors or hormonal changes. CFS/ME is most easily diagnosed when formerly active adults become ill, and is most commonly diagnosed in young to middle aged adults, although it is also reported in children, adolescents and the elderly.

Research suggests that CFS/ME results from a dysfunction of the immune system. The exact nature of this dysfunction is not yet defined, but generally it can be viewed as an over active state. For a period of time it was thought that Epstein Barr Virus, which causes Mononucleosis, was the cause of this illness. However, researchers believe that the Epstein Barr Virus, when it exists, is a result or complication of CFS/ME rather than its cause.

A lack of information and awareness has led to many patients being stigmatized as hypochondriac or lazy. The Centers for Disease Control & Prevention have now recognized CFS/ME as a serious illness and have recently launched a campaign to raise public and medical awareness about it. The American Medical Association, the World Health Organization, and the National Institutes of Health are among those who have accepted CFS/ME as a legitimate physical illness and a major cause of disability.

According to The Center for Disease Control (CDC), CFS/ME affects more than 1 million people in the United States. According to The University of Maryland Medical Center, four in every 1000 Americans are affected by CFS/ME. CFS patients are denied insurance benefits and do not seek medical treatment.

This illness strikes more people in the United States than multiple sclerosis, lupus, lung cancer or ovarian cancer. According to a large 1999 US study, the highest rates of CFS/ME were found among women in general. Chronic fatigue is most often experienced by individuals 40 to 50 years old; it is least prevalent in people under 29 or over 60. This disorder, however, occurs in both sexes and at all ages and in all racial and ethnic groups.

Researchers continue to explore possible causes and risk factors for CFS/ME. Many questions remain, but there are some characteristics that may help indicate who is most at risk for CFS/ME:

• CFS/ME occurs four times more frequently in women than in men, although people of either gender can develop the disease.


• The illness occurs most often in people in their 40s and 50s, but people of all ages can get CFS/ME.


• Children and adolescents are not immune to its effects. Most studies indicate that girls are more apt to develop CFS/ME than boys, although one study found the incidence of the syndrome to be equal. According to a 1999 study, half of the children and adolescents with CFS/ME also suffer psychiatric disorders, primarily anxiety, and also depression.


• CFS/ME occurs in all ethnic and racial groups, and in countries around the world. Research indicates that CFS/ME is at least as common among African Americans and Hispanics as it is among Caucasians.


• People of all income levels can develop CFS/ME.


• CFS/ME is sometimes seen in members of the same family, but there's no evidence that it's contagious. Instead, there may be a familial or genetic link. Further research is needed to explore this.