Spatial and temporal inequalities in malaria incidence and mortality among children aged 0–4 years in Somalia: a subnational analysis, 2010–2019

BACKGROUND: Malaria is a leading cause of under-5 mortality in sub-Saharan Africa. In Somalia, Plasmodium falciparum predominates and transmission shows spatial and seasonal variation. This study analyzed subnational inequalities in malaria incidence and mortality among children aged 0-4 years to inform targeted control strategies. METHODS: This retrospective subnational analysis used modeled annual estimates of Plasmodium falciparum incidence, Plasmodium vivax incidence, and malaria mortality among children aged 0-4 years across Somalia's 18 regions (2010-2019), sourced from the Institute for Health Metrics and Evaluation via the World Health Organization Health Equity Assessment Toolkit. Five inequality measures (Difference, Ratio, Between-Group Variance, Population Attributable Risk, Population Attributable Fraction) were calculated within the Toolkit's online software, following the Strengthening the Reporting of Observational Studies in Epidemiology guidelines. RESULTS: Plasmodium falciparum incidence rose sharply between 2010 and 2015, peaking at 51.6% in Awdal, and remained elevated in central and southern regions through 2019 (Bay 32.0%; Juba Dhexe 31.1%). Plasmodium vivax stayed low and spatially homogeneous (Difference ≤ 0.3). The between-group variance for Plasmodium falciparum peaked at 64.3 in 2015 and declined to 20.2 by 2019, while the ratio fell from 5.6 to 1.9. Mortality inequalities widened, with the difference rising from 33.9 (2010) to 118.5 (2014), the between-group variance from 100.6 to 1152.7, and the ratio remaining at 4.24 in 2019. CONCLUSIONS: Despite narrowing incidence gaps, children in central and southern Somalia were over four times more likely to die than those in least affected regions, reflecting structural healthcare inequalities.