Chronic fatigue syndrome is defined as chronic fatigue that lasts at least 6 months and cannot be explained by any other illness. This severe disabling disease begins abruptly with a range of flu-like symptoms including muscle fatigue, fevers, lymph-node swelling, persistent diarrhoea, joint and body pain, digestive problems, inability to think, loss of short-term memory and depression. This is followed by months or years of sometimes disabling lethargy ranging to chronic exhaustion and impaired cognition. The controversial and mysterious ailment has gone by various names for more than a century. Most doctors recognize the condition, others are skeptical about its existence, wondering if such fatigue is psychologically perpetuated.
The latest research on what causes chronic fatigue syndrome are testing two hypotheses. One involves previous findings that patients with CFS who have no psychiatric problems have abnormalities in the structure of their brains; the other concerns preliminary data that CFS patients have something wrong with their hearts or blood vessels.
One major outbreak was of 183 cases near Lake Tahoe, California between 1984 and 1986. In 1995, 1 million Americans had chronic fatigue syndrome. In 1995 the syndrome was still not recognized in France, Spain, the Netherlands and Germany.