Abstract:

ObjectiveTo characterize the epidemiological patterns and temporal trends of human brucellosis in Inner Mongolia Autonomous Region for evidence for developing corresponding prevention and control strategies. Methods Individual case data of human brucellosis reported in Inner Mongolia from 2015 to 2025 were retrieved from the Chinese Disease Control and Prevention Information System. Descriptive epidemiological methods were used to analyze the characteristics of temporal, regional and population distribution. The SaTScan 9.4 software was applied for spatiotemporal scan statistics, and Joinpoint regression was used to assess temporal trends. Results From 2015 to 2025, a total of 150 092 human brucellosis cases were reported in Inner Mongolia Autonomous Region, with an average annual reported incidence of 55.48/100 000. No deaths occurred. Joinpoint regression analysis revealed an overall upward trend in the reported incidence of human brucellosis in Inner Mongolia from 2015 to 2025 (AAPC=8.35%, t=3.79, P<0.05), during which the trend from 2015 to 2017 was not statistically significant (APC=1.80%, t=0.40, P>0.05), yet a significant increase was observed from 2017 to 2021 (APC=31.50%, t=13.90, P<0.05), and a significant decrease occurred from 2021 to 2025 (APC=-10.90%, t=-5.65, P<0.05). The peak incidence period was from April to August, accounting for 52.24% (78 410/150 092) of all cases. The number of reported cases was 102 731 for males and 47 361 for females, with a male-to-female ratio of 2.17∶1. The majority of cases were seen in the population aged 30-69 years (88.17%, 132 338/150 092). Farmers constituted the predominant occupation (77.87%, 116 884/150 092), followed by herders (9.56%, 14 354/150 092). The average annual reported incidence in eastern Inner Mongolia (66.01/100 000) was higher than that in western regions (43.53/100 000). Spatiotemporal clustering analysis identified five high-risk clusters, involving 32 banners/counties/districts. The median interval from symptom onset to diagnosis was 13.42 (4.38, 31.71) days, showing an overall downward trend (AAPC=-7.31%, t=-3.49, P<0.05). The proportion of cases with an interval ≤15 days showed an overall upward trend (AAPC=7.45%, t=3.54, P<0.05). Conclusion The incidence of human brucellosis in Inner Mongolia Autonomous Region shows an overall upward trend, for which our recommendation is to strengthen the inter-departmental joint prevention and control mechanisms as well as take comprehensive prevention and control measures to further contain the epidemic.

Key words: Human brucellosis, Epidemiological characteristics, Incidence trend, Spatiotemporal clustering, Inner Mongolia Autonomous Region