From Big Medical Encyclopedia

CONTAGEOUSNESS (Latin contagiosus infectious, infectious; synonym infectivity) — ability of infectious diseases to be transferred from sick people and animals healthy. The concept «contageousness» is connected with formation of a kontagionistsky view of the reason of «general» diseases, according to Krom their distribution is caused by transfer of the live activator «contagium vivum». The centuries-old discussion between the kontagionist and defenders of a miazmatichesky hypothesis considering by the reason of infectious diseases of a miasma, arising and airborne, water and the soil, as we know, ended with a victory of the first that promoted formation of the theory of epidemiology. According to the doctrine of kontagionist, the contagion as the reason of diseases is in a body of the patient and is transmitted healthy at contact with the patient through the things which were at it in use, sometimes, dissipating in air, gets to healthy at inhalation. It caused in the subsequent creation of evidence-based classification of infectious diseases by the mechanism of transfer of their activators and development effective protivoepid. actions. However only on a basis mikrobiol, opening properties of causative agents of diseases were precisely characterized and laws of epidemiology are formulated, the considerable data explaining conditions and the reasons of distinctions To are saved up. separate infectious diseases. Long since a quantitative index of degree To. to this or that infectious disease served the index of contageousness defined through percent of the diseased from among the persons endangered infection (which were in limits epid, the center) for a certain span. Index of contageousness — the size determined by number of clinically expressed cases of a disease which emergence depends on interaction of such variables as biol, properties of this strain of the activator, intensity and duration of time of its allocation from an organism of the owner, from a way of distribution of the activator and its survival in the environment and, at last, from degree of a susceptibility of the person. An indicator To. can point features of different infectious diseases under existing conditions or to different conditions at this disease.

Degree To. various infectious diseases it is not identical. So, nearly 100% of people have clinically expressed forms of measles and the index of contageousness of this disease makes 0,98, and epid, less than a half of the persons endangered infection has parotitis (an index of contageousness 0,35 — 0,40).

See also Infectious diseases .

Bibliography: V. D's white hares. Epidemic process (Theory and method of studying), M., 1964, bibliogr.; Gromashevsky L. V. About methodological bases of the doctrine about transmissibility of infectious diseases, in book: Some the philosopher, vopr, medical and natural sciences, under the editorship of L. V. Gar-kusha, Saturday. 2, page 17, Kiev, 1960.

A. A. Sumarokov, H. M. Nikityuk.