[Viral infections in chronic fatigue syndrome]

Chronic fatigue syndrome (CFS) is a heterogeneous illness in which patients can have different, overlapping signs and symptoms. No single underlying cause has been established for all CFS patients. Epidemiological studies reveal that a flu-like sickness precedes the onset in the majority of cases. The major hypothesis of the pathogenesis of CFS is that infectious agents such as viruses, may trigger and lead to chronic activation of the immune system with abnormal regulation of cytokine production. Many studies have been performed to identify the possible microbial triggers and to understand the epidemiological microbial agents. We have summarized the recent progressive literature of virus, rickettsia, and mycoplasma implicated in the pathogenesis of CFS.