Burden stratification and spatial analysis for malaria chemoprevention in Malawi

Malaria remains a leading cause of morbidity and mortality in Malawi, particularly among children under five years of age, with substantial geographic variation in transmission. Although malaria chemoprevention is effective, evidence on how malaria burden, climatic conditions, population exposure, and spatial dependence can inform its geographic prioritisation in Malawi remains limited. This study aimed to develop composite measures of malaria burden, climatic suitability, and population exposure, assess climatic influences and spatial dependence on malaria transmission and identify geographic priority areas for malaria chemoprevention.

District-month malaria surveillance, climate, and population data from 2021-2023 were analysed. Composite indices and spatial mapping assessed malaria burden, climatic suitability, and population exposure. Fixed-effects and spatial panel models assessed climatic influences and spatial dependence. These indicators were integrated into a composite priority score to identify geographic priorities for chemoprevention.

Nkhata Bay, Nkhotakota, Salima, and Neno were classified as very high-burden districts, while Mwanza was classified as high burden. Rainfall was positively associated with malaria incidence, whereas rainfall anomalies were negatively associated with transmission (both p < 0.001). Significant spatial dependence (ρ = 0.34-0.49; p < 0.001) indicated geographic interdependence in malaria outcomes. Integrated analysis identified priority areas, particularly in central and southern Malawi, where epidemiological, climatic, population, and spatial risks converged.

Integrating malaria burden, climatic suitability, population exposure, and spatial dependence can support evidence-based geographic prioritisation of malaria chemoprevention and targeted malaria control planning in Malawi.