Objective To understand the epidemiological characteristics and spatiotemporal clustering of human anthrax in Sichuan Province during 2006−2025 and provide evidence for the improvement of the prevention and control of anthrax.

Methods The incidence data of human anthrax in Sichuan during this period were collected from surveillance report management module of China Disease Prevention and Control Information System for a descriptive epidemiological analysis on the time, space and population distributions of the cases. Joinpoint regression model was used to analyze the temporal trend of the annual incidence rate of reported human anthrax. Global and local spatial autocorrelation analyses were conducted to analyze the spatial distributions of human anthrax.

Results A total of 2503 cases of human anthrax were reported in Sichuan during 2006−2025, with an average annual incidence rate of 0.15/100000. The reported incidence rate in the province showed no significant change over time average annual percentage change (AAPC)=0.293%, 95% confidence interval (CI): −1.884% to 1.796%, P=0.686. The clinical types of reported cases were predominantly cutaneous anthrax (98.92%); the annual incidence peak occurred during July-September (42.51%); and the cases were mainly men (69.08%), young and middle-aged adults aged 20−<50 years (69.32%), and farmers and herdsmen (91.33%). The reported cases were distributed in 36 counties (districts) in 6 prefectures in Sichuan, with the majority being reported in Aba (59.65%) and Garzê prefectures (32.60%). and the incidence rate in Ganzi showed an upward trend (AAPC=7.83%, 95%CI: 5.264% to 10.450%, P<0.05). The top five counties (districts) with high average annual incidence rate were Ruoergai (53.30/100,000), Hongyuan (51.79/100000), Aba (14.05 /100000), Shiqu (13.19/100000), and Seda (9.48/ 100000). The results of global spatial autocorrelation analysis showed that there was spatial clustering in human anthrax cases in Sichuan from 2006 to 2025 (all Moran's I>0.00, Z>1.960, P<0.05). The local spatial autocorrelation analysis showed that the range of high-high clustering areas expanded continuously over time, from 3 counties (districts) during 2006−2010 to 10 counties (districts) during 2021−2025, showing a spread from pastoral area to semi-agricultural-pastoral area.

Conclusion The incidence of human anthrax in Sichuan showed obvious occupational characteristics, with herdsmen and farmers being the mostly affected. The human anthrax epidemic mainly occurred in pastoral area, but showed a spread to semi-agricultural-pastoral area. It is necessary to strengthen the prevention and control of human anthrax in such areas.