SUMMARY
From 1991, links between CFS and Rickettsial Diseases were uncovered because of their similar clinical presentation. Further research linked them even more. Five Rickettsia strains, suspected to be the cause, or an important factor in CFS, were identified by means of the Giroud Micro-Agglutination test and were widely found to be positive in patients' serum, diagnosed as suffering from CFS, Fibromyalgia, Rheumatoid Arthritis, Multiple Sclerosis, Depression, Psychosis, Heart Diseases, and Auto-Immune Diseases. This finding leads us to submit those originally differently diagnosed patients to the same tetracycline treatment. This proved to be a great success. The increasing number of patients gave us the opportunity to establish a biological checklist (regardless of the diversity of the pathology) of infections, organs' functions and auto-immune profile. We found the differences in positivity to depend on four factors: length of illness, virulence of germs, cohabitation of germs, and the state of the host immune system. These studies suggest that auto-immune diseases could have an infectious origin. Better knowledge and mastery of the co-factors would be determinant in speeding recovery. With this approach, CFS patients are being treated for the cause of their illness rather than symptomatically.