benign myalgic encephalomyelitis appeared as an entry to the International Classification of Diseases under Diseases of the nervous system. In 1986, Ramsay published the first diagnostic criteria for ME, in which the condition was characterized by: 1) muscle fatiguability in which, even after minimal physical effort, three or more days elapse before full muscle power is restored; 2) extraordinary variability or fluctuation of symptoms, even in the course of one day; and 3) chronicity. By 1988, the continued work of Ramsay had demonstrated that, although the disease rarely resulted in mortality, it was often severely disabling. Because of this, Ramsay proposed that the prefix "benign" be dropped. Chronic fatigue syndrome In the mid-1980s, two large outbreaks of an illness that resembled mononucleosis drew national attention in the United States. Located in Nevada and New York, the outbreaks involved an illness characterized by "chronic or recurrent debilitating fatigue, and various combinations of other symptoms, including a sore throat, lymph node pain and tenderness, headache, myalgia, and arthralgias". An initial link to the Epstein-Barr virus had the illness acquire the name "chronic Epstein-Barr virus syndrome". In 1987, the CDC convened a working group to reach a consensus on the clinical features of the illness. The working group concluded that CFS was not new, and that the many different names given to it previously reflected widely differing concepts of the illness's cause and epidemiology. The CDC working group chose "chronic fatigue syndrome" as a more neutral and inclusive name for the illness, but noted that "myalgic encephalomyelitis" was widely accepted in other parts of the world. In 1988, the first definition of CFS was published. Although the cause of the illness remained unknown, several attempts were made to update this definition, most notably in 1994. The most widely referenced diagnostic criteria and definition of CFS for research and clinical purposes were published in 1994 by the CDC. In 2006, the CDC commenced a national program to educate the American public and health-care professionals about CFS. Other medical terms A range of both theorised and confirmed medical entities and naming conventions have appeared historically in the medical literature dealing with ME and CFS. These include: Epidemic neuromyasthenia was a term used for outbreaks with symptoms resembling poliomyelitis. Iceland disease and Akureyri disease were synonymous terms used for an outbreak of fatigue symptoms in Iceland. Low natural killer syndrome, a term used mainly in Japan,