Epidemiologic characteristics of typhoid fever and paratyphoid fever in Jinhua, Zhejiang, 2005–2019

ObjectiveTo analyze the epidemiologic characteristics of typhoid fever and paratyphoid fever in Jinhua, Zhejiang province, from 2005 to 2019, and provide basis for the formulation of prevention and control strategies.

MethodsThe method of descriptive epidemiology was used to analyze the incidence data of typhoid fever and paratyphoid fever collected from the disease prevention and control information system in China, the related annual thematic survey data and some laboratory test results.

ResultsA total of 1 356 cases of typhoid fever and paratyphoid fever were reported in Jinhua from 2005 to 2019, including 595 typhoid fever cases and 761 paratyphoid fever cases, accounting for 43.88% and 56.12% respectively. No deaths were reported. The average annual incidence rate was 1.71/100 000. After 2007, the incidence showed a downward trend year by year ( χ²=951.941, P=0.000). The incidence of typhoid fever and paratyphoid fever was high in summer and autumn, and varied with area, the incidence rates were relatively high in Pujiang, Yiwu and Wuyi of Jinhua. The cases were mainly distributed in <1/5 townships (streets), accounting for 2/3 of the total cases. Only 7 townships (streets) had cumulative case numbers ≥ 50, but their cases accounted for 43.44%. The cases mainly occurred in children aged 0–4 years and young adults aged 15–39 years. The incidence in men was higher than that in women, and most cases were farmers, migrant workers and children outside child care setting. The clinical detection results of 21 cases of typhoid fever and 50 cases of paratyphoid fever were investigated retrospectively, 14 cases of typhoid fever and 19 cases of paratyphoid fever had definite results of bacterial culture and identification. Two strains of Salmonella typhi and 20 strains of Salmonella paratyphi B were reexamined. The detection results of serotypes of 2 strains of S. typhi and 5 strains of S. paratyphi B were consistent with previous detection results. Fifteen strains of S. paratyphi B were identified as non-typhoid Salmonella.

ConclusionSince 2005, the incidence of typhoid fever and paratyphoid fever in Jinhua had gradually decreased, and the distribution of cases showed area, season and population specific clustering. There was a certain proportion of false positives in the reported cases in Jinhua, and the etiological surveillance for typhoid fever and paratyphoid fever has not been carried out in Jinhua, and the changes of bacterial types and drug resistance spectrum are unclear. It is necessary to strengthen the training on diagnostic criteria and detection techniques of typhoid fever and paratyphoid fever in clinical doctors and laboratory technicians, and the standardized etiological surveillance for circulating strains should be conducted as soon as possible.