[Analysis of epidemiological characteristics of pertussis in Hunan Province, 2019-2023]

Objective: To analyze the epidemic characteristics of pertussis in Hunan Province from 2019 to 2023 and provide a reference basis for formulating prevention and control strategies for pertussis. Methods: The data were derived from the Infectious Disease Surveillance Information System of the Chinese Disease Prevention and Control Information System. Descriptive epidemiological methods were used to analyze the three-dimensional distribution characteristics of pertussis cases. The susceptible-exposed-asymptomatic infected-infected-recovered (SEAIR) model was constructed to fit the actual case data, and the real-time reproduction number (R_t) was calculated to assess the risk of epidemic transmission. Data organization and visualization were carried out using WPS 2025 software, spatial autocorrelation analysis was conducted using ArcGIS 10.2 software, and SEAIR model fitting was performed using Berkeley Madonna 10.6.1 software. Results: From 2019 to 2023, the number of reported pertussis cases in Hunan Province generally showed a trend of first decreasing and then increasing (trend χ²=483.82,P<0.001), with 13 567 reported cases and a reported incidence rate of 4.101 per 100 000. The reported incidence rate ranked highest in 2023 (8.264 per 100 000). The reported peak incidence period occurred mainly between May and September each year. The cases are mainly in the 0-9 age group (94.97%,12 885/13 567), with scattered children, students, and children in kindergartens and nurseries accounting for 65.61%(8 902/13 567), 17.28% (2 344/13 567), and 15.71% (2 131/13 567), respectively. Moreover, there was no statistically significant gender difference in the reported incidence rate (P=0.782). The top three reported incidence rates were Xiangxi Tujia and Miao Autonomous Prefecture (1.394 per 100 000), Loudi City (0.569 per 100 000), and Xiangtan City (0.498 per 100 000). Global autocorrelation analysis shows that the cases in 2019 and 2021-2023 have spatial clustering. Local autocorrelation analysis shows that high-high clustering areas existed in each year, with concentrations mainly in the Xiangxi Tujia and Miao Autonomous Prefecture from 2021 to 2023. The SEAIR model shows a good fit (2019-2023 average R² =0.908), with the highest goodness-of-fit in 2023 (R²= 0.973). The average R_t was 1.129 across 2019-2023, while the years with the lowest and highest daily R_t values were 2020 (R_t=0.919) and 2023 (R_t=1.278), respectively. Conclusions: From 2019 to 2023, the pertussis epidemic in Hunan Province showed a trend of first decreasing and then increasing, with obvious seasonality (high incidence from May to September), population specificity (mainly in the low age group of 0-9 years old and scattered children), and regional clustering (Xiangxi Tujia and Miao Autonomous Prefecture). It is recommended that the national pertussis vaccination program be continuously implemented. For key gathering areas and other key locations, case screening, health education, and environmental disinfection should be strengthened during the high-incidence season to reduce the impact of pertussis on the population's health.