Analysis on epidemiological characteristics of human brucellosis and case detection delay in Daxing district, Beijing, 2013−2022

Objective To analyze the epidemiological characteristics, incidence trend and infection source of human brucellosis in Daxing district of Beijing from 2013 to 2022 and provide data support for the prevention and treatment of human brucellosis in Daxing.

Methods The incidence data of human brucellosis in Daxing during this period were collected from National Infectious Disease Reporting Information Management System for a descriptive epidemiological analysis on the epidemiological characteristics, incidence, pathogen testing, clinical manifestations, sources of infection and etiological detection of reported human brucellosis cases. The differences in incidence of human brucellosis among different years and between men and women were compared with χ² test. Joinpoint regression model was used to analyze the changing trend of detection delay of human brucellosis cases.

Results From 2013 to 2022, a total of 130 cases of human brucellosis were reported in Daxing, The annual average incidence rate was 0.79/100000. The cases mainly occurred in rural area and urban-rural continuum, and incidence rate was high during summer - autumn. There were significant differences in incidence rates among years (χ²=18.828, P=0.027), between men and women (χ²=28.494, P＜0.001), and among age groups (χ²=36.287, P＜0.001).The average medical care-seeking delay rate of the human brucellosis cases was 33.33% (40/120), and there was no significant difference in annual medical care-seeking delay rate annual percentage change (APC)=−6.31%, 95% confidence interval (CI): −44.03%−56.84%, t=−0.315, P=0.777, the median time of medical care-seeking was 6 days. The average diagnosis delay rate from 2013 to 2022 was 50.83% (61/120). The annual diagnosis delay rate generally showed a downward trend, with an average annual decrease of 12.0% average annual percentage change (AAPC)=−11.40%, 95%CI: −23.56%−2.72%, t=−1.623, P=0.108. The segmented analysis results of the Joinpoint regression model showed that the diagnosis delay rate showed a downward trend year by year from 2013 to 2018, and the difference was significant (APC=−34.12%, 95%CI: −47.76%−−17.11%, t=−4.708, P=0.006), there was no significant difference in the change in diagnosis delay rate from 2018 to 2022 (APC=28.40%, 95% CI: −7.27%−77.82%, t=2.014, P =0.105). The median interval between onset and diagnosis of the cases was 10 days, showing an overall downward trend from 19 days in 2013 to 5 days in 2022 (χ²=17.395, P<0.001)

Conclusion From 2013 to 2022, the obvious seasonal and area differences were observed in the incidence of human brucellosis in Daxing. The rate of detection delay of the human brucellosis cases was relatively serious, but showed a decreasing trend over time. It is necessary to take joint and comprehensive prevention and control measures.