Spatial Vulnerability Mapping of Climate-Sensitive Diseases in Petro-Coastal Delta State, Nigeria: A Multi-Criteria Composite Index Approach

Abstract

Climate-sensitive diseases pose growing threats in petro-coastal regions, where climate hazards intersect with environmental degradation and socioeconomic vulnerability in Delta State, Nigeria, yet no spatially explicit vulnerability index exists. We developed and validated a Composite Vulnerability Index (CVI) for 25 LGAs using 14 indicators across exposure (temperature trend, rainfall CV, heatwave days, flood frequency, gas flaring proximity), sensitivity (under-5 proportion, elderly proportion, poverty rate, low education), and adaptive capacity (ITN use, water treatment, health access, early warning, PHC density). Indicators were normalized, dimension scores averaged, and CVI computed as arithmetic mean. Validation used disease hotspots (Getis-Ord Gi*), community perception (12 FGDs), expert opinion (30 KIIs), and health facility data. Sensitivity analysis tested alternative weightings; VIF (<3.1) confirmed no multicollinearity. CVI ranged from 0.12 to 0.89 (4.9-fold gradient). Three LGAs (Bomadi, Burutu, Patani) showed extreme vulnerability (CVI>0.75). ANOVA confirmed significant dimension differences across categories (p<0.001). Bootstrapped 95% CIs were narrow (±0.02-0.05); spatial autocorrelation (Moran’s I=0.68, p<0.001) confirmed clustering. Sensitivity analysis showed high ranking robustness (Spearman r=0.94-0.96). Validation demonstrated strong convergence with disease hotspots (r=0.85), community perception (100% agreement on top 3 LGAs), expert opinion (κ=0.78), and health facility data (r=0.72). Three priority intervention zones were identified: Zone 1 (3 LGAs, ₦500M), Zone 2 (4 LGAs, ₦200M), Zone 3 (18 LGAs, ₦100M). The CVI reveals a stark 4.9-fold vulnerability gradient, with adaptive capacity—not climate exposure—as the critical bottleneck. This evidence-based tool enables targeted resource allocation for climate-resilient health systems globally.