Waning Success: a 2013-2022 spatial and temporal trend analysis of malaria in Ethiopia

Abstract

Background After consecutive decades of success in reducing malaria, Ethiopia went off target to meet the 2030 malaria elimination goal. The current nationwide malaria outbreaks are attributed to emergence and spread of diagnostic and drug resistant Plasmodium falciparum, increased insecticide resistance and the spread of invasive Anopheles stephensi. COVID-19 pandemic, environmental anomalies and internal conflicts are also potential factors for malaria increase. This study aimed to evaluate the contribution of environment and An. stephensi in the spatiotemporal trends of malaria in Ethiopia.Methods A negative binomial regression model was used to describe variability and potential overdispersion in the weekly number of malaria cases across Ethiopian zones. Its components included fixed and random effects, temporal trends, zone-specific seasonality, and zone-level spatial trends.Results Significant temporal trend in malaria risk was observed nationwide, a decline from 2013 to 2018 followed by a sharp increase starting in early 2022. While environmental variables were able to explain slightly over half (55%) of the variability, the rest was captured by a residual seasonal variation; itself showing large geographic clusters. Zones of the western and northwestern regions exhibited higher malaria risks compared to other zones. The spread of An. stephensi did not emerge as contributor in our model.Conclusions The waning in the success of malaria program in Ethiopia could palpably eased by having due focus on predictable environmental factor. The random local spatiotemporal variations shaping malaria risk distribution emphasize the need for tailored intervention and better understanding of underling factors that potentially drive local epidemic.