[The epidemic process in infections before and after active immunization. I. Comparison of long-term monitoring of the disease with a simple mathematical model].

In the first part of this paper the authors used for demographic data and morbidity data concerning measles, parotitis, rubella and chickenpox in the Sokolov district a model of exponential distribution, in particular its distribution function. The authors introduced the concept of mean population year. They tested the theoretical assumption that in different infections in long-term average the annual number of infected subjects is equal and equals the mean population year. They found that the delta parameter which determines the shape of the exponential regression curve and is the measure of the rate of spread of a given infection, expressed at the same time numerically by the number of mean population years the mean number of susceptibles which remain permanently in a given population.