Epidemiological characteristics and spatio-temporal clusters of human brucellosis in Inner Mongolia, 2010-2021

Abstract

Background: Brucellosis poses a significant public health challenge in China. Inner Mongolia, characterized by its developed livestock industry, is the most severe endemic area for human brucellosis. This study aims to describe the epidemiology, explore the spatial-temporal distribution patterns, and clustering characteristics of human brucellosis in Inner Mongolia.

Methods: Data on human brucellosis cases from 2010 to 2021 were obtained from the Centers for Disease Control and Prevention in Inner Mongolia. Spatial autocorrelation analysis was used to identify high-risk areas, while spatial-temporal scan statistics were employed to detect changes in clusters over time.

Results: A total of 153,792 brucellosis cases were reported in Inner Mongolia from 2010 to 2021, with an average annual incidence rate of 52.59 per 100,000 persons. The incidence showed a decreasing trend from 2010 to 2016, followed by a significant increase from 2016 to 2021. The disease exhibited distinct seasonality, peaking in spring and summer (March to August). Middle-aged individuals, males, and farmers/herdsmen had higher incidence rates. Spatially, incidence rates decreased from north to south and from the central and eastern regions to the west. Clear spatial clusters were observed during 2010-2013 and 2016-2021 in the global Moran's I test. Local spatial autocorrelation analysis revealed that high-high clusters expanded from the central and eastern regions towards the west over time. Spatio-temporal scan analysis further indicated that high-risk clusters were primarily concentrated in the central and eastern regions, with a continuous expansion towards the west and south, leading to an increasingly broad geographical spread.

Conclusion: Human brucellosis cases in Inner Mongolia exhibit spatio-temporal clustering, with spatial concentration in the central and eastern regions, but also observed expansion towards the western and southern regions. The most of cases occur between March and August each year. For high-risk areas and populations, more timely and effective prevention and control measures should be implemented to mitigate the spread of brucellosis and protect public health.

Keywords: Brucellosis; Epidemiological characteristics; High-risk areas; Inner Mongolia; Spatial autocorrelation; Spatiotemporal analysis.

Fig. 1

Age and gender distributions of human brucellosis cases in Inner Mongolia,2010–2021

Fig. 2

Proportion of human cases on occupation in Inner Mongolia,2010–2021 (Farmers refer to those who primarily cultivate crops, Herders specialize in raising and management of livestock.)

Fig. 3

Annual reported cases and incidence rate of brucellosis in Inner Mongolia,2010–2021

Fig. 4

Seasonal and temporal trend of brucellosis in Inner Mongolia (2010–2021)

Fig. 5

Incidence rate zones of human brucellosis in counties of Inner Mongolia, 2010–2021

Fig. 6

Local spatial autocorrelation analysis of human brucellosis in Inner Mongolia, 2010–2021

Fig. 7

Spatial–temporal clustering of human brucellosis cases in Inner Mongolia, 2010–2021

Fig. 8

Annual sSpatio-temporal clustering of brucellosis cases in Inner Mongolia from 2010 to 2021(The blue circles represent clustering arearegions, with the largest circle implying the most likely cluster.)