Chronic fatigue syndrome: thoughts on pathogenesis.

Studies have shown that a proportion of patients with severe chronic infection due to Epstein-Barr virus (EBV) lack antibody to a component of EBV nuclear antigen. However, it is not clear whether this circumstance is one of cause or effect in regard to the pathogenesis of chronic fatigue syndrome (CFS); it is clearly not pathognomonic since it also occurs in persons infected with the human immunodeficiency virus and--rarely--in those with other EBV-related conditions. Stress and depression may be other pathogenetic mechanisms that could reactivate EBV and lead to CFS; examples of this phenomenon are given. The syndrome might also follow certain other viral infections as part of a process that has been called postinfectious neurasthenia. Currently, the cause(s) and cure of CFS, a common and distressing syndrome, are enigmatic and require multidisciplinary study.