Expanding mountain-type zoonotic visceral leishmaniasis in China: a multi-source data-driven investigation

Background: Mountain-type zoonotic visceral leishmaniasis (MT-ZVL) is undergoing rapid re-emergence in central China and demonstrates significant potential for further dissemination. The aim of this study was to provide information on optimal control strategies by estimating the disease's current distribution and potential for spread into new areas. Methods: vector and infectious canines) and socioeconomic covariates to predict the relative risk of transmission at the 1 × 1 km resolution across central China. Model performance was validated using 239 unique, geolocated human case occurrences (2022-2024). This allowed us to map the MT-ZVL risk and quantify the populations at-risk within stratified risk tiers. Findings: sandflies, 224 infected canines and 213 human case records. Extreme gradient boosting demonstrated superior predictive performance for human MT-ZVL infection risk, significantly outperforming benchmark models, with the area under the curve (AUC) of 0.950 (95% CI: 0.921-0.979) in internal validation and 0.913 (95% CI: 0.886-0.940) in external validation. Model performance was further validated by 88.3% of indigenous cases occurring within predicted high-risk zones. These high-risk zones were concentrated in hilly terrain along the Taihang, Lvliang and Qinling Mountains-primarily in central-southern Shanxi, Hebei-Shanxi border regions, eastern Shaanxi and north-western Henan. This study identified 117 high-risk or very high-risk counties with a combined population of 19.24 million. Medium-risk areas were found to encompass surrounding regions across Shanxi, Shaanxi, Henan, eastern Gansu, central-western Hebei and western/northern Beijing (87 counties; 12.07 million residents), while low-risk zones covered 87 counties in eastern Gansu, northern Sichuan, north-western Henan and central Hebei mountains (15.35 million residents). The optimized multi-source data-driven model exhibited robust predictive performance, identifying 291 at-risk counties threatening about 46.67 million residents. Interpretation: and infectious canines in non-endemic areas signifying new emerging foci. By the identification of specific regions at risk for MT-ZVL, an evidence base warranting heightened public health vigilance against potential transmission has been established. Surveillance for MT-ZVL in central China and targeted interventions are strongly recommended. Funding: This work was supported by the National Natural Science Foundation of China (No. 32161143036, No. 82473688), National Key Research and Development Program (2021YFC2300800, 2024YFC2310902), the Three-Year Initiative Plan for Strengthening Public Health System Construction in Shanghai (2023-2025) (No. GWVI-11.1-12).