[Characteristics of the seasonal distribution of typhoid fever cases in different areas of the USSR].

The results of the monthly registration of typhoid cases in all union republics and in the USSR as a whole for the period of 1970--1976 were analyzed. The mathematical parameters of the monthyly distribution of morbidity rate under the influence of long-term factors for each union republic were determined. In analyzing actual morbidity rates for definite years these data may help determine to what extent such rates are influenced by incidental factors. Mathematical analysis allowed to divide the territory of the USSR into 5 groups of areas with different patterns of the seasonal distribution of typhoid cases: the RSFSR, the Ukrainian SSR and the Moldavian SSR, the Byelorussian SSR and the Soviet Baltic republics, the Transcaucasian republics, the republics of Central Asia and the Kazakh SSR. April was found to be the optimum time for the immunoprophylaxis of typhoid fever throughout the whole territory of the USSR in the presence of epidemiological indications.