The Spatiotemporal Epidemiology and Influencing Factor Analysis of Leptospirosis - Anhui Province, China, 2004-2023

Leptospirosis has historically been a severe public health concern across multiple Chinese provinces. Despite an overall decline in incidence in recent years, the disease continues to exhibit fluctuations and occasionally triggers localized outbreaks. This study aimed to characterize the demographic and spatiotemporal patterns of leptospirosis in Anhui Province - a historically significant epidemic region - from 2004 to 2023, to investigate potential climatic and environmental risk factors, and to identify critical targets for disease prevention and control.

Spatiotemporal cluster analysis was conducted using SaTScan software. Spearman correlation analysis was performed using SPSS to examine the short-term lagged effects of rainfall, temperature, and normalized difference vegetation index (NDVI) on leptospirosis incidence in the high-risk counties of Huaiyuan and Jingde.

A total of 458 leptospirosis cases were reported across Anhui Province during the 20-year study period. Middle-aged individuals (40-59 years), males, and agricultural workers constituted the primary high-risk populations. Spatiotemporal scanning identified nine adjacent hotspots in southern Anhui during 2004-2012, with a subsequent shift to Huaiyuan County in the northern Huaihe River Basin during 2016-2021. Significant associations were observed between leptospirosis cases and temperature, rainfall, and NDVI in both Huaiyuan and Jingde counties.

This study revealed significant spatial heterogeneity, distinct spatiotemporal clustering patterns, and potential climatic and environmental risk factors for leptospirosis in Anhui Province during 2004-2023. These findings provide critical information regarding target regions, high-risk populations, and climatic and environmental factors to inform early warning systems and enhance prevention and control strategies for leptospirosis.