Abstract:

ObjectiveTo analyze the incidence and diagnostic delay of human brucellosis in Chongqing area to provide a scientific basis for optimizing prevention and control strategies. Methods The case data on human brucellosis in Chongqing City from 2011 to 2025 were obtained from the Chinese Disease Prevention and Control Information System. Joinpoint regression analysis was conducted to analyze the trend of reported incidence and diagnostic delay rate of brucellosis. ArcGIS hotspot analysis tool was used for spatial hotspot analysis. Results From 2011 to 2025, a total of 766 cases of brucellosis were reported in Chongqing City, with an average annual incidence rate of 0.17 per 100 000 population. The diagnostic delay rate was 61.23% (469/766), and the median diagnostic delay was 21 (8, 61) days. Joinpoint regression analysis showed that the reported incidence rate of brucellosis in Chongqing exhibited a fluctuating upward trend from 2011 to 2025 (AAPC=43.81%, t=4.35, P<0.001). The diagnostic delay rate presented a fluctuating downward trend (AAPC=-4.47%, t=-3.70, P<0.001). Spatial analysis revealed that the cases were mostly reported in the Three Gorges Reservoir area of northeastern Chongqing (222 cases, 28.98%) and the western Chongqing (218 cases, 28.46%). The diagnostic delay rate was relatively higher in the Three Gorges Reservoir area of northeastern Chongqing (64.41%, 143/222) and the Wuling mountainous area of southeastern Chongqing (63.36%, 83/131). The hotspots of reported incidence shifted from Pengshui Miao and Tujia Autonomous County and Wulong District to Wushan County and Tongnan District by 2025, while no significant spatial clustering of diagnostic delay rate was observed. The cases were chiefly reported in males (546 cases, 71.28%), population aged 45-59 years (383 cases, 50.00%), farmers and herdsmen (459 cases, 59.92%), and residents living in townships (547 cases, 71.41%). The diagnostic delay rate was the highest in males (62.45%), the age group ≤14 years (85.71%), township residents (61.61%), and farmers and herdsmen (60.57%). A relatively large number of cases were reported from tertiary hospitals (560 cases, 73.11%). Conclusion In the past years, the reported incidence rate of brucellosis in Chongqing City has shown a fluctuating upward trend, and the diagnostic delay rate has been improved, yet primary healthcare institutions lack the capacity to confirm the diagnosis. These findings suggest that training for the primary healthcare providers should be strengthened to improve their ability to identify and differentiate brucellosis at an early stage.

Key words: Human brucellosis, Incidence trend, Diagnostic delay, Spatial hotspot, Chongqing City