Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) or Chronic Fatigue and Immune Dysfunction Syndrome (ME/CFS) is a serious, poorly-understood and often disabling condition. The cause(s) and cure remain elusive, although research over the past two and half decades have shed much light on triggers/causes of the mysterious illness.

Routine medical tests usually yield normal results, and there is an absence of a specific diagnostic test that can distinguish between a sick patient from a normal person. This disorder can be diagnosed by a physician based on established criteria from the Centers for Disease Control (CDC). The cause of illness should be ascertained by careful evaluation of the initial flu-like illness, if available. ME/CFS follows an unpredictable cycle, often waxing and waning. Treatment is largely symptom-based and individualized, since symptoms and responses to medications vary from person to person. Specific therapy may be possible within the next decade since emerging evidences support the role of chronic virus infection in this illness.

At least 800,000 American men and women have ME/CFS when estimated 20 years ago. The number has increased to 7.5 million (2.5% of the U.S. population) according to CDC study published in 2007. Adolescents and children are afflicted as well as older patients. Most of the patients are white female in the 3rd and 4th decade of life. People of all racial and economic backgrounds get ME/CFS.