The possible role of infectious agents

"...several studies have found that human herpes virus 6 (HHV-6) is activated more often than in controls in patients with CFS. However, a causal role for HHV-­6 has not yet been established."

"More circumstantial evidence for a chronic vi­ral infection in many patients comes from reports of an abnormality in an anti-viral lymphocyte enzyme system called the 2-5A pathway. One laboratory has found this antiviral pathway to be chronically act­ivated in patients with CFS. Another case-control study, involving more than 700 patients from 2 different geographical areas, found a much higher frequency of atypical lymphocytes in patients with CFS than in healthy controls."

Citation: "A 56- Year-Old Woman With Chronic Fatigue Syn­drome," JAMA October 18; 278 (14) (1997) :1179­-1185.