Chapter One, Course WB1032
Overview of CFS
Chronic fatigue syndrome (CFS) is a complex illness characterized by profound fatigue of at least six months’ duration that results in substantial reduction in occupational, personal, social or educational activities; the fatigue is not improved by rest, may be worsened by physical or mental activities, and is accompanied by characteristic symptoms (impaired memory or concentration, unrefreshing sleep, headaches, muscle pain, joint pain, sore throat and tender cervical/axillary nodes). CFS is marked by a dramatic difference in pre- and post-illness activity level and stamina.
Most people with CFS who consult health care professionals describe their illness as beginning suddenly over a period of hours or days. In contrast, most people with CFS who are identified in community studies describe a gradual onset of illness over weeks or months. The clinical course of CFS varies considerably among people with the condition and frequently has an intermittent pattern of relapse and remission. As yet, there are no diagnostic tests or laboratory markers for CFS, and its pathophysiology remains unknown. Selected research findings will be discussed in this course.
Illnesses similar to CFS have been documented for several centuries, some possibly linked to bacterial, viral or protozoal infections such as brucellosis, yellow fever, hepatitis, influenza and malaria.
CFS was first formally defined in 1988 (Holmes et al.) following studies by CDC in Incline Village, Nevada. However, similar illnesses have been described for many years and known by many names. Current interest in CFS began in the early 1980s when several groups around the U.S. identified patients with chronic fatiguing illnesses thought to be prolonged infectious mononucleosis based on the clinical presentation and laboratory evidence of what was then considered an active Epstein Barr virus (EBV) infection. Subsequent studies of these cases, including one in Incline Village, Nevada, did not support a role for an active response to EBV. When the illness was first defined in 1988 the name chronic fatigue syndrome was selected because a more specific name implying known pathophysiology would have been misleading and because the most common and prominent symptom was found to be chronic fatigue (Holmes et al.).
Various terms are incorrectly used interchangeably with CFS. CFS has an internationally accepted case definition that is used in research and clinical settings. The name chronic fatigue and immune dysfunction syndrome (CFIDS) was introduced soon after CFS was defined; there is no case definition for CFIDS, and the name implies an understanding about the pathophysiology of CFS that is not fully supported in the medical literature. The name myalgic encephalomyelitis (ME) was coined in the 1950s to clarify well-documented outbreaks of disease; however, ME is accompanied by neurologic and muscular signs and has a case definition distinct from that of CFS.
Content Source: National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)