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Chronic Fatigue Syndrome (CFS)

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Chronic Fatigue Syndrome Overview

Chronic fatigue syndrome (also called CFS) is a disorder without a known cause, although CFS may be related to a previous infection. CFS is a state of chronic fatigue that exists without other explanation for six months or more and is accompanied by cognitive difficulties (problems with short-term memory or concentration). You may have CFS if you meet the following criteria:

if you have severe chronic fatigue for six months or longer and all other known conditions that could cause fatigue have been excluded by your health-care provider, or

if you simultaneously have four or more of the following symptoms: significant problems with short-term memory or concentration, sore throat, tender lymph nodes, muscle pain, pain in several joints without swelling or redness, headaches that are different in pattern or severity from previous headaches, feeling tired and unrefreshed even after sleeping, and extreme tiredness lasting more than 24 hours after you exercise or exert yourself.

Chronic fatigue syndrome affects tens of thousands of people. It occurs more commonly in females than in males. This condition occurs most commonly in young to middle-aged adults. People with CFS are often unable to perform normally at work and home because of their long-term fatigue and problems with short-term memory. This can lead to depression, but depression is not a cause of CFS.

Chronic Fatigue Syndrome Causes

The cause of CFS is unknown, but the condition may be related to infection with effects on the immune system. Several viruses have been studied as possible causes of CFS, but no cause-and-effect relationship has been discovered. Some evidence indicates that the bacterium Chlamydia pneumoniae (which causes pneumonia and other illnesses) may be a cause of CFS in some cases. People with chronic fatigue syndrome related to C. pneumoniae are most likely to respond to antibiotics that kill C. pneumoniae, and their CFS symptoms may improve with antibiotic medications such as doxycycline. However, this association is still being debated. Various unrelated infections appear to lead to long-term fatigue in some people. If the fatigue is accompanied by problems with short-term memory or concentration, CFS is possible.

One of the associated infections is the Epstein-Barr virus, or EBV. EBV causes mononucleosis, also called "mono" or the "kissing disease." Although associated in some cases, EBV does not cause CFS, and CFS is not the same thing as long-term EBV infection or long-term mononucleosis.