Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), also know as systemic exertion intolerance disease, post-viral fatigue syndrome or chronic fatigue immune dysfunction syndrome, is a complex, multi-symptom disorder of unknown etiology. It usually has a sudden onset, triggered by infection or other stress (e.g., immunization, anesthetics, blood transfusions, physical trauma, environmental chemicals). Its hallmark is a profound physical and mental fatigue along with a cascade of other symptoms (including pain, cognitive dysfunction, sleep disturbance flu-like symptoms, irregularities of the autonomic, immune and metabolic systems as well as neurological symptoms such as migraine and sensitivities) that worsen with physical or mental exertion (referred to as post-exertional malaise or PEM), are not refreshed by sleep, and persist for years, with most patients never regaining their pre-disease level of health or functioning.
There are no approved therapeutics for ME/CFS forcing patients to rely on equivocal symptomatic treatments. ME/CFS affects up to 2.5 million Americans, resulting in annual direct and indirect economic costs of $17-24 billion.
ME/CFS is one of a group of etiologically unexplained diseases, including:
- fibromyalgia syndrome;
- chronic lyme disease;
- Gulf War Illness;
- post-traumatic stress disorder;
- atypical depression;
- irritable bowel syndrome; and
Collectively, these have been argued to represent one underlying common basic syndrome, sometimes referred to as functional somatic syndrome or bodily distress syndrome.