[Epidemiological characteristics and spatial clustering of human brucellosis in Hunan Province, 2016-2024]

Objective: To understand epidemiological characteristics and spatial clustering of human brucellosis in Hunan Province from 2016 to 2024 and provide a scientific basis for its prevention and control. Methods: The surveillance data on human brucellosis in Hunan Province from 2016 to 2024 were collected through the Chinese Disease Prevention and Control Information System. The time, population, and geographical distribution characteristics of the human brucellosis epidemic in Hunan Province were analyzed using descriptive epidemiological methods. The GeoDa 1.16 software was used for global autocorrelation and local autocorrelation analyses. The source of infection, transmission route, and serological results of key populations were also analyzed. Results: From 2016 to 2024, Hunan Province reported 2 241 cases of human brucellosis, with no reported deaths, resulting in an average annual incidence rate of 0.37 per 100 000 population. The incidence was on a fluctuating rise (trend χ²=263.21, P<0.001). The peak incidence was concentrated from March to August (spring and summer). The male-to-female ratio of cases was 2.81∶1 (1 653∶588). The age distribution of the cases mainly concentrates in the range of 40-69 years. The occupations were mainly those of farmers. The cases involved 122 counties (cities, districts) in 14 cities (prefectures). The incidence areas showed an expanding trend, and the cities with the highest incidence rates were Chenzhou (0.84/100 000), Yongzhou (0.79/100 000), and Huaihua (0.60/100 000). There was a spatial positive correlation (Moran's I ranged from 0.095 to 0.341, all P<0.05) of incidence, high-high clustering areas were mainly distributed in the western and southern regions of Hunan Province. There was no correlation between the number of cattle/sheep and the incidence of human brucellosis (all P>0.05). The primary sources of infection were sheep and cattle, and the transmission route was mainly feeding and grazing. The positive rate of serologic surveillance in key populations was 1.71%. Conclusions: The annual incedence of human brucellosis in Hunan showed a fluctuating rise trend during 2016-2024. Spring and summer were the seasons with high incidence. The reported incidence of brucellos showed spatial clustering. The western and southern regions of Hunan are key areas, and monitoring should be strengthened, multiple departments should work together to carry out joint prevention and control.