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Chronic Fatigue Syndrome
Centers for Disease Centrol and Prevention, National Center for Infectious Diseases, Division of Viral and Rockettsial Diseases
Publication date: 08/01/1991
Table of Contents
General descriptionChronic Fatigue Syndrome, or CFS, comprises a complex of symptoms characterized by chronic, debilitating fatigue and other nonspecific symptoms. It has no known cause and may actually include several similar illnesses with different causes. In some persons, the symptoms of CFS develop following an otherwise self-limited illness, such as influenza, infectious mononucleosis, acute cytomegalovirus (cy-to-meg-lo-virus) infections, or a nonspecific acute viral syndrome. However, in many people CFS symptoms develop gradually over weeks to months, with no recognized precipitating event.
CFS may vary widely in severity, but many patients have become severely disabled and are unable to work or even to participate in many routine activities of daily living for prolonged periods. With possible rare exceptions, CFS is not a progressive disease. For most people, symptoms plateau early in the course of illness and persist or recur with varying degrees of severity for at least six months. Death resulting from CFS has not been reported. CFS does not appear to be directly transmissible from person to person, and there is no apparent justification for persons with CFS sufferers to be isolated from other persons.
CFS has been diagnosed in a wide variety of persons, ranging from young children to adults in their 60's. CFS patients come from widely ranging income levels as well. CFS appears to be more common in females than in males, although this may be the result of underdiagnosis in males. In an effort to get better estimates of its frequency, the Centers for Disease Control has initiated a CFS Surveillance and Follow-up System in four sites across the United States. This should provide the population using well defined diagnostic criteria, and over time may indicate if the syndrome is stable or increasing in frequency.
Possible causes of Chronic Fatigue SyndromeCFS most likely represents not one disease, but a combination of symptoms and physical findings that may be caused by several different diseases. A number of infectious and immunologic causes have been proposed, but the cause or causes of CFS remains unknown.
Possible Viral CausesSeveral viruses have been investigated as possible causes of CFS, including the Epstein-Barr virus (EBV), cytomegalovirus (CMV), Coxsackie B virus, and adenovirus (a-den-o-virus) type 1. None of these agents has been more than circumstantially associated with CFS. Although groups of CFS patients have been found to have higher antibody levels, or titers, against these viruses than healthy control groups, the results overlap sufficiently to make the tests useless in diagnosing CFS in an individual case. For this reason, such antibody tests, or serologic tests, are not recommended for use in diagnosing CFS.
Recent attention has been focused upon human herpesvirus type 6 (HHV6, also known as human B-lymphotropic (lymph-o-tropic) virus, or HBLV), a recently discovered virus that now seems unlikely to be the cause of CFS. One study reported that about 70% of CFS patients, 85% of persons with miscellaneous other disorders, and 12% of healthy persons had antibodies against this virus, suggesting that persons with a variety of illnesses may have secondarily increased HHV-6 titers. Recent studies at CDC, using a more sensitive enzyme-linked assay, have detected HHV-6 antibodies in more than 95% of healthy persons. As is true with EBV and other viruses, levels of HHV-6 antibodies do not correlate with clinical activity of the virus and may be nonspecific immune responses to a variety of stimuli. The measurement of HHV-6 antibodies is of no known diagnostic value for CFS.
A defective rubella vaccine was proposed to be related to CFS, but this hypothesis has not been substantiated. Rubella vaccine remains one of the safest vaccines available, and persons at risk of acquiring rubella should receive the vaccine if recommended by their physicians. CFS is not associated with the acquired immune deficiency syndrome (AIDS), although AIDS may cause symptoms resembling CFS.
Several subtle immunologic abnormalities have been described in some patients with CFS, although various studies have generated conflicting results. No single abnormality has been distinctly linked with CFS. Some of the reported abnormalities include low levels of certain gamma globulin types, detectable circulating immune complexes, increased ratios of "helper" to "suppressor" T-lymphocytes (T-lymph-o-cytes), and low numbers and/or decreased functional ability of natural killer (NK) cells in groups of CFS patients. NK cells are a subset of lymphocytes that may play a role in the host's early defense against viral infection.
The significance of these findings is uncertain. Most of these immunologic abnormalities have also been reported to occur in association with other diseases, and are therefore nonspecific. Some may reflect preexisting immune dysfunction, while others may result from an underlying disease process manifesting as CFS.
Psychological Aspects of Chronic Fatigue SyndromeThere is a great deal of controversy regarding the role of psychological factors and psychiatric diseases in causing CFS. Many of the physical symptoms of CFS -- headache, muscle aches, difficulty in concentrating and sleep disorders -- are also characteristic of primary mood disorders. However, other symptoms -- sore throat, fever, lymph node enlargement, and joint pains -- suggest an underlying physical illness. Some patients state that CFS symptoms began at points in their lives when they were under great psychological stress, suggesting that stress may contribute to the illness. Several reports have recently suggested that depression, anxiety disorder, or other psychiatric diseases may predispose individuals to CFS. The majority of CFS patients describe themselves as depressed or anxious, but many say that the depression and anxiety developed after the onset of CFS and is a natural consequence of a chronic physical illness. A number of current studies are attempting to assess the importance of psychiatric factors in causing or perpetuating CFS.
Diagnostic criteriaCFS was defined by a panel of experts in 1988 as an illness lasting at least 6 months, characterized by chronic or recurrent, debilitating fatigue combined with at least 6 of the following chronic symptoms: headache, fever or feverishness, sore throat, muscle aches, joint pains, generalized muscle weakness, lymph node pain, prolonged fatigue following exercise, sleep alterations, and various nervous system complaints, for which no likely explanation has been identified after thorough medical and laboratory evaluation. Many people have been diagnosed with CFS without fulfilling these criteria or receiving a full evaluation for other chronic diseases.
There is no absolute means of confirming the diagnosis of CFS. No known laboratory tests are of proven positive diagnostic value. As a result, CFS should be considered by the physician only after a thorough evaluation for other potential causes of illness. Some possible causes of CFS-like symptoms include autoimmune diseases such as systemic lupus erythematosus (e-ryth-e-ma-to-sus), malignancies such as breast or ovarian cancer, lymphoma, thyroid disease, brain tumor, infectious diseases such as endocarditis, encephalitis, hepatitis, syphilis, or AIDS, and a variety of chronic diseases of the heart, lungs, liver, kidneys, gastrointestinal tract, endocrine system, or musculoskeletal (mus-cu-lo-skel-e-tal) systems.
Diagnostic evaluationIt is very important for the patient with CFS symptoms to be fully evaluated for other chronic diseases. Chronic fatigue, as an isolated symptom, is common in the general population, and CFS appears to be present in only a small fraction of persons who have complaints of chronic fatigue. Many well-recognized medical diseases, such as lupus, various cancers and lymphomas, chronic heart, lung, and other diseases, and primary psychiatric disorders, such as major depression or anxiety states, can produce chronic fatigue and must be considered in the differential diagnosis of CFS. Most of these diseases can be treated or managed appropriately following diagnosis and some may be progressive or even fatal if untreated, justifying the cost in time and money of a full medical evaluation. It is also advisable to periodically repeat such evaluations -- there have been several cases in which patients diagnosed with CFS have later been found to have a specific disease, such as a connective tissue disorder or other chronic illness, that was likely to have caused their CFS symptoms from the beginning.
CDC cannot recommend specific physicians for referral. Our general recommendation is to consult an infectious disease specialist or the infectious disease department at a university affiliated medical center in your area if you feel you need further evaluation, or to ask your county medical society for a referral.
TreatmentAlthough there have been numerous claims of therapeutic breakthroughs, no proven effective cure for CFS now exists. Treatment should be initiated only after a thorough evaluation for other chronic diseases by a reputable physician. Most experts begin by recommending a regimen of balanced diet, adequate rest, and physical conditioning. Moderate exercise, not to the point of exhaustion, is generally helpful. However, CFS patients often report relapses of severe fatigue and other symptoms after over-exerting themselves.
Symptomatic treatment is often helpful in reducing symptoms to tolerable levels. This includes anti-inflammatory agents for headaches, and muscle and joint pains. Low doses of anti-anxiety drugs have been anecdotally reported to be of value.
Many CFS patients suffer from depressive symptoms, such as sleep disturbance, loss of enjoyment of life, and decreased appetite. Low doses of antidepressant drugs, taken at bedtime, have been reported to improve many of these and other CFS symptoms. In persons who have depressive symptoms, formal psychological testing should be performed to confirm their severity. For such patients, full doses of antidepressants may be expected to produce significant improvement. Antidepressant drugs are very potent and have a number of possible sideeffects. They must be used under the careful guidance of a physician. A variety of antidepressant agents are available, each with its own range of side-effects. If one agent fails to be tolerated, another may be tried.
All treatments have potential side effects, and in many instances the risk of side effects outweighs the potential beneficial effect of treatment. A number of currently used treatments are of no proven value, are often costly, and may actually be harmful. Only one agent, acyclovir, has undergone rigorous clinical testing, and it was recently reported to be no more effective than a placebo in treating CFS patients. Some successes have been reported in small numbers of patients, using a wide range of treatments, including antiviral and immunomodulating (im-mu-no- mod-u-la-ting) drugs, vitamins, holistic remedies, diet modifications, and activity reduction. However, such anecdotal reports are often based upon faulty study design and the results cannot be distinguished from a placebo effect or the natural course of the illness. Several formal treatment trials are in planning stages around the country and may shed new light on the treatment of CFS.
For further informationThere are several national and local non-profit support groups for persons who are thought to have the chronic fatigue syndrome. These groups publish periodic newsletters and provide lists of interested physicians and telephone numbers of other affected persons who can provide assistance in dealing with the illness. The Centers for Disease Control and Prevention does not necessarily endorse these organizations or their published information. They are included as further sources of information. Contact:
- The National CFS Association, 919 Scott Avenue, Kansas City, KS 66105. Tel. (913) 321-2278.
- The CFIDS Association, Community Health Services, P.O. Box 220398, Charlotte, NC 28222-0398. Tel.(704) 362-2343
- The CFIDS Society, Box 230108, Portland, OR 97223.
- Minann, Inc., Box 582, Glenview, IL 60025.
- Consult your local newspaper for local support groups.
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