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Chronic fatigue syndrome (ME/CFS)

Chronic fatigue syndrome (CFS) is a disease currently unknown to which multiple triggers have been attributed, but none of these is present in all patients. Perhaps the approach to have is that not only one determinant factor or pathogen can produce this disease but several and therefore it is necessary to analyze the etiopathogenesis of each and every one of the possible pathogens involved, as well as their way of eluding the immune system, to understand how it can generate metabolic and physiological changes produced in patients.

CFS usually begins with an infectious process in a generally active person that begins with fever, cough, odynophagia, myalgia… that is to say, flu-like symptoms. From this beginning, a permanent exhaustion is established that does not improve with rest, it worsens with both physical and mental activity that becomes persistent. When chronic symptoms are established, fatigue tends to predominate. In addition, fever (at the onset of the illness) or temperatures of 35ºC appear when the illness is more advanced, arthralgias, myalgias, cervical adenopathies, intestinal symptoms, increased respiratory allergies, hormonal alterations… etc. It should be noted that all these symptoms are not present in all patients and that their heterogeneity may be due to the previous serological profile of the person and the initial pathogen, which may generate different symptoms, such as arthritis, based on previous reactivations of past viruses.1

Therefore, we will classify these patients in subgroups and we will try to demonstrate how the machinery of these pathogens can elude the immune system and establish the disease.


  1. Barbado Hernández F. J.; Gómez Cerezo J.; López Rodríguez M.; Vázquez Rodríguez J. J. El Síndrome de Fatiga Crónica y su diagnóstico en medicina interna. Anales de Medicina Interna (Madrid) Mayo-2006, vol. 23 Nº 5, pp.239-244. ISSN 0212-7199. Available in: