一、引言从1959年开始,我国各地伤寒的发病率呈现上升的趋势。例如,河南省1959年伤寒发病率为1958年的6倍;吉林省1959年伤寒发病率为1958年的5.3倍。特别是近二、三年来,各省广大农村伤寒暴发流行的报告增多,其中以水型暴发为主,流行季节的发病率最高可达 I. Introduction Since 1959, the incidence of typhoid fever in various parts of China has shown an upward trend. For example, the incidence of typhoid fever in Henan Province in 1959 was six times that in 1958; the incidence of typhoid fever in Jilin Province in 1959 was 5.3 times that of 1958. Especially in the past two or three years, there has been an increasing number of reports of widespread epidemic of typhus among rural provinces, of which the most is the outbreak of water-borne type, with the highest prevalence in the epidemic season