Epidemic (Greek, literally "in, on the people") - a continuous process of successive homogeneous infectious diseases (epidemic process), expressed in their significant spread in the community, settlement, district, country. Depending on the greater or lesser number of cases, different degrees of intensity of the epidemic process are noted: 1) sporadic morbidity - single infectious diseases that occur in a settlement without a visible epidemiological connection between them (for example, in the period exceeding the incubation period of the disease); 2) epidemic outbreak - group diseases in a limited area (team, settlement, district), associated with a common source of infection; 3) epidemic - a significant excess of the number of cases of infectious diseases in a community, district, country; 4) pandemic (Greek, literally "the whole people") - a strong epidemic, dramatically exceeding in its intensity the usual epidemic, spreading among the population on large territories, sometimes entire countries and even the whole world.