A member of the herpesvirus family and one of the most common human viruses. Most people are infected with it at some point in their lives, and it usually causes no symptoms or mild illness. When infection occurs during adolescence or early adulthood, it can cause infectious mononucleosis.
The Epstein-Barr virus is known to effect the central nervous system in some rare cases. When the virus does cause symptoms, they generally resolve in less than 2 months, though the virus remains in the body for life in a dormant state.
Some experts on chronic fatigue syndrome believe this virus or a reactivation of it can trigger chronic fatigue syndrome in people who are genetically predisposed to the condition. More research is needed to confirm this link.