The word 'epidemiology' has been used since the time when most of
the infectious diseases were epidemic. Today, when infectious morbidity
has considerably decreased, the concept of epidemiology includes
the study of objective laws of aetiology, distribution and control of
infectious diseases in a human community, and also elaboration of
methods to prevent and control these diseases.
The following definition of the term 'epidemiology' was formulated
at the International Symposium of Epidemiologists in Prague (1960):
"Epidemiology is an independent branch of medicine studying
aetiology and spreading of infectious diseases in a human community
and is aimed at prevention, control, and final eradication of these
diseases".
General and special epidemiologies are distinguished. General
epidemiology studies the laws of distribution of infectious diseases
among people (characteristics of sources of infection, the mechanism
of transmission, susceptibility to infection, and the like) and the
general principles of prevention and control of these diseases. Special
epidemiology studies epidemiologic characteristics of each particular
infectious disease and the methods to prevent and control it.
History of epidemiology. Ancient people had their own concept of
contagiosity of some diseases and took first prophylactic measures;
they rejected people with infectious diseases from their community,
used variolation (deliberate inoculation with smallpox virus), disinfection,
etc. All these measures were empirical and their efficacy was
low. At those times it was impossible to prove instrumentally that
infectious diseases might be evoked by living microorganisms, but