Constant tiredness. Other use: Inflammation General.Encyclopedia Entry for Chronic Fatigue :Chronic fatigue syndrome - resources. Resources - chronic fatigue syndrome; CFS resources.Encyclopedia Entry for Chronic Fatigue :Chronic Fatigue Syndrome. Can be caused by Enteroviruses (Coxsackie B virus), Epstein-Barr virus, Human Herpesvirus 6 variant A, Human Herpesvirus 7, Parvovirus B19, XMRV and bacteria Coxiella burnetii and Chlamydia pneumoniae.Information from Marcello Allegretti.