Dual infections of the immune system in patients with chronic active Epstein-Barr virus infection mimicking chronic fatigue syndrome.

The etiologic bases of CFS are undetermined at the present time. It is very important to distinguish the patients with CFS as defined by the Centers for Disease Control (CDC) case definition of Holmes et al. from patients with physical and laboratory findings suggesting dual infections and/or underlying immunodeficiency. Particularly fruitful might be a longitudinal immunovirologic study of patients who exhibit CFS following a well-documented viral infection.