Wildlife Disease and Zoonotics


Date of this Version

February 1968


Fort Detrick
Frederick, Maryland


The Main structural indices of a nosoareal are the focalress in the distribution of infectious diseases of man and their causative agents. The problem of the focalness of infections has been developed for quite a long time in the field of parasitology and is a very important division of contemporary epidemiology (Ye. N. Pavlovskiy, 1939, 1944, 1955, 1960, 1961, 1964; L. V. Gromashevskiy, 1941, 1949, 1965; I. I. Yelkin, 1951, 1960, 1962; P. A. Petrishcheva, 1955, 1959, 1965; V. N. Beklemishev, 1956, 1959, 1961; Yu. M. Rall, 1958, 1965; V. V. Kucheruk, 1959, 1960, 1965; A. G. Voronov, 1965, and others). For the resolution of this problem the greatest importance belongs to working out problems dealing with the population structure of the parasitic species, since there is a profound inner bond between the distribution of the infectious disease and the populations of the causative agent (V. N. Beklemishev, 1959, 1961).

The smallest territorial groupings of parasitic species are the elementary populations (according to V. N. Beklemishev, micropopulations and hemipopulations), which represent the population of parasites of a specific species in the individual organism of a host.

It is clear that an organism, populated by a concrete elementary population, may turn out to be the source of infection for other susceptible organisms, and with the realization of a conceret mechanism of transmission may become an individual link in the epidemic or epizootic process. As a result of this, such an organism (source of infection) along with the susceptible organisms surrounding it, who are threatened by tne danger of transmission of the infection, become the smallest elementary territorial unit of the epidemic or epizootic process. Such a territorial unit is defined as an epidemic (epizootic) focus.