Objective  To analyze the epidemiological trends of human brucellosis in northeastern China (including Liaoning, Jilin and Heilongjiang provinces, and Chifeng, Tongliao and Hulunbuir prefectures, Xing'an and Xilin Gol leagues of Inner Mongolia autonomous region) from 2014 to 2023 and and provide theoretical evidence for the targeted prevention and control of human brucellosis.

Methods  The incidence data of human brucellosis reported in northeastern China from 2014 to 2023 were collected from China Information System for Disease Control and Prevention. Joinpoint regression analysis was used to detect the long-term incidence trends. Spatial autocorrelation analysis was used to examine the spatial distribution of brucellosis at prefectural level. In the areas with relatively high incidence rates, distributed lag non-linear model (DLNM) was constructed to explore the potential lagged effects of meteorological factors on the incidence of human brucellosis.

Results  A total of 163,406 human brucellosis cases were reported in northeastern China during the study period, with an average annual reported incidence rate of 13.95/100,000. The incidence of human brucellosis showed a decrease trend from 2014 to 2017 annual percentage change (APC) =−11.04%, P=0.089, an increase trend from 2017 to 2021 APC=19.40%, P<0.05) , and a rapid decrease trend after 2021 (APC=−17.10%, P=0.120). The annual incidence peaked during April - June. Spatial autocorrelation analysis indicated significant clustering (global Moran’s I: 0.13～0.26, P<0.01), although the degree of clustering diminished over time. THe high-high (H-H) clustering areas were mainly distributed in western area, such as Xing’an league, Xilin Gol league, and Tongliao prefecture of Inner Mongolia, while the low-low (L-L) clustering areas were mainly distributed in southeastern area, including Tonghua and Baishan prefectures of Jilin. In the five prefectures (leagues) of Inner Mongolia, the reported human brucellosis case counts were positively correlated with temperature and sunshine (correlation coefficients: 0.25 and 0.32, respectively), and negatively correlated with atmospheric pressure (correlation coefficient: -0.42) (all P<0.05). DLNM analysis results revealed that low temperature had prolonged lag effect (peak lagged by2.00 months), while high temperature exerted more immediate effect (peak lagged by 0.6 months).

Conclusions  The incidence of human brucellosis in northeastern China showed a spatiotemporal distribution with high level in western area and low level in eastern area, which was influenced by seasonal and meteorological factors. It is necessary to strengthen the cross-area surveillance and coordinated control efforts, especially in in western pastoral area. Furthermore, attention should be paid to the lagged effects of meteorological factors for the more precise prevention and control of human brucellosis.