Climate change reshapes the potential transmission risk of human alveolar and cystic echinococcosis in western China: a projection based on MaxEnt models

BACKGROUND: Echinococcosis, a severe zoonotic parasitic disease, imposes a significant health burden in western China, primarily as alveolar (AE) and cystic (CE) forms caused by Echinococcus multilocularis (Em) and E. granulosus sensu lato (Egsl), respectively. Its transmission, tied to a complex host cycle, is strongly influenced by climatic factors. This study aimed to model the ecological niches of these parasites, validate predictions with epidemiological data, and project the impact of climate change on future transmission risk geography. METHODS: Utilizing location data of 1247 human cases diagnosed in western China from 1981 to 2016, obtained from the National Echinococcosis Control Program, and contemporary climate data, we developed optimized Maximum Entropy (MaxEnt) models. This involved defining an appropriate spatial resolution, screening 19 bioclimatic variables to select key predictors (7 for Em, 6 for Egsl), and identifying optimal model parameters. Model performance was evaluated using the Area Under the Curve (AUC) and AUC of 10% Receiver Operating Characteristic (AUCpROC) curve, and validity was assessed via correlation with county-level incidence. Future habitat suitability was projected for multiple periods (2011-2100) under three climate scenarios (SSP-126, SSP-370, SSP-585) generated by 5 global climate models. RESULTS: The models demonstrated high predictive accuracy (AUC > 0.92; AUCpROC: 0.084 for Em, 0.070 for Egsl) and a significant positive correlation with incidence (ρ > 0.6, P < 0.0001). Em and Egsl exhibited distinct climatic niches: Em prefers cool, stable climates with moderate summer moisture, while Egsl spreads in areas with dry-cold winters, warm-humid summers, and moderate seasonality. Future projections reveal a spatially heterogeneous reshaping of risk. While overall suitability increases, Em's suitable area is projected to shift toward higher altitudes (e.g., expanding in Qinghai and Xizang but contracting in Ningxia and Gansu). In contrast, Egsl shows widespread outward expansion from current endemic margins, particularly across the Tibetan Plateau. Qinghai and Xizang are identified as key expansion hotspots for both Em and Egsl. CONCLUSION: The findings confirm distinct ecological drivers for the suitability of Em and Egsl, and indicate that climate change will potentially shift the endemic areas of AE and expand those of CE in western China. This underscores the necessity for forward-looking, spatially targeted surveillance and control strategies, informed by a One Health approach, to mitigate the evolving burden of echinococcosis.