Chronic Fatigue Syndrome and Herpesviruses: the Fading Evidence.

Herpesviruses, in particular Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus 6 (HHV-6), have, for the past two decades, come under considerable scrutiny as aetiological agents of chronic fatigue syndrome (CFS). However, virological findings of herpesviruses in CFS have not been consistent between different studies, and the unusual patterns of serological responses to EBV, CMV and HHV-6 have not been specific for CFS, being observed also in asymptomatic individuals. In addition, patients with symptomatology suggestive of CFS do not appear to have an increased frequency of these herpesviruses, as detected by culture or polymerase chain reaction, compared with controls, which argues against an ongoing active herpetic infection. Studies have also shown that the presumable elevation of antibody titres to EBV, CMV or HHV-6 in CFS are not observed only with these viruses, but also with other organisms such as herpes simplex virus and measles.