CHRONIC FATIGUE SYNDROME

(CFS) also called postviral fatigue syndrome, or low natural killer cell syndrome, disorder characterized by at least six months of debilitating fatigue that begins suddenly and is usually accompanied by mild fever, sore throat, tender lymph nodes, muscle pain and weakness, joint pain, headache, sleep disorders, confusion, memory loss, and visual disturbances. Once routinely dismissed as an imagined rather than a specific physical condition, chronic fatigue syndrome remains controversial. Indeed, many authorities still question whether it is a distinct disorder. No definitive diagnostic test has been developed yet, and CFS is commonly confused with such illnesses as chronic Epstein-Barr virus infection and myalgic encephalomyelitis. Although a number of theories about the cause of CFS have been advanced, not one has been proved. No effective treatment has been found, but only a few sufferers become progressively worse; most improve gradually, and some eventually achieve full recovery.