Changing Patterns of Epidemiological Characteristics and Spatial-Temporal Clusters of Human Brucellosis Based on County Level - China, 2011-2023.

INTRODUCTION

Human brucellosis persists as a critical public health challenge in China. Understanding disease clusters and trends is essential for implementing effective control strategies. This study evaluates the epidemiological characteristics and spatiotemporal distribution of brucellosis in China from 2011 to 2023.

METHODS

Data were obtained from the National Notifiable Disease Reporting System (NNDRS). We conducted descriptive epidemiological analyses and employed SaTScan10.1 and ArcGIS10.7 software to identify disease clusters and generate county (district)-level incidence maps.

RESULTS

The incidence of human brucellosis in Chinese mainland increased substantially between 2011 and 2023, rising from 38,151 cases (2.8/100,000) across 834 counties (25.4%) to 70,439 cases (5.2/100,000) across 2,290 counties (76.9%). A significant upward trend in reported incidence emerged during 2018-2023 (average annual percentage change (AAPC)=14.9%, =0.01). Most cases (89.3%) occurred in individuals aged 25-69 years, with an increasing proportion among those aged over 60 years. While 96.1% of cases were reported in northern provincial-level administrative divisions (PLADs), southern regions demonstrated escalating incidence rates and expanding geographical spread. Southern PLADs exhibited a notable annual increase of 31.5% in reported incidence (<0.01). Counties (districts) with incidence rates exceeding 10 per 100,000 expanded geographically from northwestern pastoral regions to southern areas and from rural to urban settings. Primary spatiotemporal clusters were concentrated in Inner Mongolia and adjacent provincial-level administrative divisions (PLADs), with emerging clusters identified in Yunnan, Guangdong, and Xizang.

CONCLUSIONS

The human brucellosis epidemic in China continues to intensify, characterized by rebounding incidence rates and broader geographical distribution across counties (districts). While spatiotemporal clusters remain predominantly centered in Inner Mongolia and neighboring regions, targeted interventions and increased resource allocation for high-risk areas and populations are imperative.