[Role of epidemiological science and practice in protecting the health of the population of the country].

The historical stages of the development of epidemiology as a science with a specific object of study, is summarized. One of the greatest theoretical generalizations is the doctrine on the natural focality of diseases. New principles of theoretical epidemiology, new theories and concepts are analyzed. The role of infectious pathology as one of the main criteria of the population health is emphasized as well as a wide spread of infectious (parasitic) diseases. The specific feature of the present stage of epidemiological situation is the dominating and constantly increasing role of viruses in the etiology of infectious diseases. The effectiveness of vaccinal prophylaxis to control vaccine-preventable infections is substantiated. The role of epidemiological science in revealing the epidemiological regularities of emerging and re-emerging infections is emphasized.