PERSISTENCE OF MYCOBACTERIA IN THE HOST -EPIDEMIOLOGY, IMMUNOPATHOLOGY AND PROPHYLAXIS OF INFECTION

Tuberculosis continues to be one of the major causes of morbidity and mortality in the developed and developing countries. There are more th an 5000 cases of active open tuberculous lung disease in Germany. Worl dwide approximately 10 million persons get tuberculous infections each year. Other not yet infected people in the community are endangered b y this disease, especially those with immunodeficiency e. g. AIDS-pati ens or tumor patients. M. tuberculosis with its unique glycolipid cell wall is fairly resistant against the immune system. Only specialized activated macrophages are able to inhibit its growth. The bacteria may persist for years in the living body, probably in granulomas. A posit ive tuberculin-reaction indicates an infection and persistance of myco bacteria but does not prove a disease. Approximately 1,5 billion peopl e are tuberculin positive worldwide. Any weakening of the immune syste m can unleash M. tuberculosis to cause reactivation and active tubercu lous disease. The main diagnostic tools since the time of Robert Koch are microscopy and culture. Neither immunserology nor polymerase chain reaction are of significant diagnostic value until now. It is possibl e to cure each new tuberculosis case by adequate and continous therapy . Resistance of M. tuberculosis against the ''classical'' antitubercul otic agents mainly arises from non-compliance of treated patients. Mul tiresistant strains make tuberculosis incurable. In Germany, in contra st to some regions in Africa, Asia or in the Unites States of America, resistance against one of the antituberculotic drugs is still relativ ely low (5-10%). BCG-vaccination is recommended for high risc-groups o nly. Preventive chemotherapy is indicated for persons with conversion of tuberculin-reaction from negative to positive. The main infectious danger results from individuals with undiscovered active tuberculous l ung disease via airborne droplet transmission. Therefore the most impo rtant task is to discover these persons in time by always considering the disease, when the corresponding symptoms are being observed. Becau se of the mentioned problems new efforts should be done to investigate the pathogenesis of the disease and its therapy with alternative drug s.