Humidex-related risk of other infectious diarrhea in Anhui, China: a multi-city study on spatial heterogeneity and socioeconomic modifiers
Climate change may influence the transmission dynamics of enteric pathogens through changes in temperature, humidity, precipitation, and environmental exposure. Humid heat poses a significant threat, yet its synergistic impact on Other Infectious Diarrhea (OID) remains under-characterized. This study quantifies humid-heat-related OID risks and investigates the socioeconomic determinants driving spatial vulnerability in Anhui, China. Daily data on OID cases ( n = 822,220) and meteorological variables were collected from 16 cities in Anhui Province (2015–2023). We employed a two-stage strategy: city-specific distributed lag non-linear models (DLNM) to estimate exposure-response associations, followed by multivariate meta-regression to evaluate geographical and socioeconomic effect modifiers. Spatial clustering was quantified using Global Moran’s I statistics. The association between Humidex and OID was non-linear, with significant spatial clustering that intensified over time (Moran’s I : 0.36–0.47, P < 0.001). Substantial heterogeneity was observed ( I ² = 70.03%), masking marked disparities: less-developed northern cities faced significantly higher risks (e.g., Bengbu, RR = 2.08) and larger disease burdens (e.g., Suzhou, AN = 7,671) than southern counterparts. Multivariate meta-regression identified urbanization rate, GDP per capita, and latitude as the primary drivers of this regional heterogeneity. Humid-heat-related OID risk is structurally modulated by socioeconomic development. Urbanization and economic capacity act as critical buffers, highlighting an “adaptation deficit” in less-developed regions. Public health interventions should prioritize high-risk northern hotspots to mitigate climate-driven health inequities.