Presence of combined natural foci of plague, tularemia, Crimean-Congo hemorrhagic fever, West-Nile encephalitis, Astrakhan spotted fever in the North-West Precaspian region was substantiated. Influence of anthropogenic and climatic conditions in formation of combined natural foci of infectious diseases of bacterial, rickettsial and viral etiology was pointed out. Up-to-date potential epidemic danger of the territories under consideration was evaluated.