Spatiotemporal heterogeneity and multiscale social influencing factors of syphilis in the mainland of China, 2005–2022

This study analyzes the spatiotemporal patterns and social determinants of syphilis in the mainland of China (2005-2022) to inform targeted resource allocation and control strategies. Using provincial-level syphilis incidence analyzed via joinpoint regression, spatial clustering, and multiscale geographically weighted regression (MGWR). We found the incidence significantly increased from 9.73 to 31.27 per 100,000 (AAPC = 6.81%), evolving through distinct "rapid increase-slow increase-decline" phases. Spatially, five distinct patterns emerged. Hotspots were concentrated in Fujian/Jiangxi, then shifted to Tibet/Xinjiang, and later spread to the central-southern regions. MGWR revealed significant spatial non-stationarity in social drivers: per capita GDP exerted a positive global effect, whereas the density of health technicians and medical institutions showed significant negative global effects, with the urbanization rate exhibiting suppressing effects globally but promoting effects locally. These findings demonstrate profound spatiotemporal heterogeneity in syphilis distribution, underscoring the necessity for differentiated prevention strategies prioritizing high-incidence border regions (e.g., Xinjiang and Tibet) and emerging risk areas (e.g., Yunnan and Guizhou).