Does the medical profession recognize “chronic fatigue syndrome” as a physical illness and, if so, how do doctors come to that diagnosis?
The U.S. Centers for Disease Control (CDC) has developed a definition of chronic fatigue syndrome (CFS) for research purposes, and most textbooks recognize and discuss the syndrome. So I guess the short answer to the question is yes, the medical profession does recognize the syndrome as a physical illness. The CDC definition excludes people who also have a psychiatric illness from the chronic fatigue category, but whether and to what degree depression plays a role in the development and continuation of the syndrome is still an open question.
What we now call CFS has probably been around for a long time, under a variety of different names, including neurasthenia, myalgic encephalomyelitis, chronic candidiasis, and chronic Epstein-Barr virus (EBV) infection, among others. Clusters of cases of CFS have been reported from all over the world, which has made many experts feel that an infectious cause must be present. However, no single infection has been identified.
CFS commonly develops in previously healthy people after they have an obvious viral infection, such as the flu. It is more common in women than in men, and the onset is usually in young adults, 25 to 40 years of age. The CDC definition requires that persistent or relapsing fatigue that is new or had a definite onset be present; that it is not relieved by rest; and that it results in a substantial reduction of previous levels of functioning. No other diseases known to cause fatigue, including preexisting psychiatric disease should be present. Several minor criteria, such as mild fever, sore throat, muscle pains, joint pains, and sleep disturbances must also be present for at least six months.
No diagnostic physical findings or laboratory findings are required for the diagnosis. Some studies have shown higher levels of some herpes viruses such as EBV and cytomegalovirus (CMV), in people with CFS, but this finding has not been consistent; since about 90 percent of the normal adult population has antibodies to EBV, the significance of this finding is dubious. Many people with CFS do have small abnormalities in their immune system functioning, and these may allow them to show higher levels of antibodies to these viruses than people without CFS.
In someone with fatigue, a thorough history, physical exam, and a few tests to exclude other causes of fatigue should be done. Most texts do not advise elaborate or expensive laboratory testing for viruses, candida etc. Treatment of many of the symptoms, such as low grade fever, headaches, muscle pains, etc., should be given, and if depression is prominent, that can also be treated. Expensive unproven treatments should be avoided. Intravenous gamma globulin treatments, which are expensive and carry some risk, have not been shown to be consistently effective. A graded exercise program is very important to prevent the physical deconditioning often seen in the syndrome from becoming worse.
Most people with CFS experience gradual improvement and complete recovery, although that may take years to achieve.