Infection and vaccination in chronic fatigue syndrome: myth or reality?

Chronic fatigue syndrome (CFS) is characterized by severe disabling fatigue lasting for more than 6 months associated with physical and mental disturbances such as headache, arthralgia, myalgia, memory impairment, sore throat and tender lymph nodes. The exact pathogenesis is still unknown. Several models were proposed to explain its etiology including chronic infection, endocrine dysfunction, autonomic imbalance, depression, decreased immunity states and an aberrant reaction to infection. No convincing evidence was found to support any of the suggested pathogenic mechanisms. The current concept is that CFS pathogenesis is a multi factorial condition in which an infective agent cause an aberrant immune response characterized by a shift to Th-2 dominant response. When the response fails to be switched-off, a chronic immune activation occurs and clinically expressed as the symptomatology of CFS. Vaccinations are used in order to stimulate the immune system to induce a persistent immunity against the favorable antigens. Several syndromes that contain chronic fatigue as one of their symptoms, such as "Gulf war syndrome" and macrophagic myofasciitis were related to vaccinations. Can vaccinations induce the aberrant immune response of CFS? Little is known about this issue. There are some reports on CFS occurring after vaccination, but few prospective and retrospective studies failed to find such an association. A working group of the Canadian Laboratory Center for Disease Control (LCDC) that was founded in order to examine the suspected association between CFS and vaccinations concluded that there is no evidence that relates CFS to vaccination. Further studies are requested to examine this issue since it is very conceivable that if infection can lead to CFS, vaccination may also lead to it in the same immune-mediated pathogenesis.