Mapping the prevalence of soil-transmitted helminth infections in the Western Pacific Region: a spatial modelling study

Background: Soil-Transmitted Helminth (STH) infections are a significant health issue in the Western Pacific Region (WPR). This study aims to produce high-resolution spatial prediction STH prevalence maps for the WPR. Methods: Bayesian model-based geostatistical frameworks were developed for each STH species (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, and hookworm) to estimate infection prevalence at a spatial resolution of 1 km². A systematic review created a comprehensive database of STH prevalence surveys, which informed the geostatistical frameworks. Logistic regression models incorporating both fixed covariate effects and spatial random effects were applied to identify drivers of spatial distribution for each species. Findings: We analysed 227 surveys from 3122 locations across 15 countries in the WPR. Between 1998–2011 and 2012–2021 substantial reductions in the pooled prevalence of hookworm (21.3%–3.7%), A. lumbricoides (21.7%–6.5%) and T. trichiura (22.5%–9.7%) were observed, while S. stercoralis prevalence increased (13.3%–18.4%). High-resolution spatial prediction maps revealed notable geographical variations in STH prevalence, with persistent hotspots identified in China, Cambodia, Malaysia, and Vietnam. Altitude and distance to health facilities were positively associated with the prevalence of hookworm and A. lumbricoides, while sand content in soil was positively associated with all STH species. In contrast, coarse soil fragments and organic carbon content were negatively associated with the prevalence of T. trichiura and A. lumbricoides. Interpretation: The high-resolution spatial prediction maps produced in this study can inform resource prioritization to accelerate STH elimination efforts. Funding: National Health and Medical Research Council (1153727 ACE-NTD).