[Analysis of the trends in typhoid-paratyphoid morbidity in the USSR]

Mathematico-statistical analysis of typhoid-paratyphoid infection morbidity in the USSR during 1900--1940 revealed a regular many-year cyclic recurrence of the changes in the morbidity level. The intensity of the morbidity level reduction at the periods of decline--in 1900--1917, 1920--1928, and in 1932--1939--was similar. A successive reduction of morbidity of this group of infections, by 6.45% on the average, annually, occurred in 1930--1976. The character of reduction of typhoid-paratyphoid infections morbidity level in the USSR during that period is well described by the exponential function.