Waning success: a 2013-2022 spatial and temporal trend analysis of malaria in Ethiopia.
Abdollah Jalilian, Galana Mamo Ayana, Temesgen Ashine, Elifaged Hailemeskel, Yehenew Asmamaw Ebstie, Eshetu Molla, Endashaw Esayas, Nigatu Negash, Abena Kochora, Muluken Assefa, Natnael Teferi, Daniel Teshome, Alison M Reynolds, David Weetman, Anne L Wilson, Birhanu Kenate, Martin J Donnelly, Luigi Sedda, Endalamaw Gadisa
Author Information
Abdollah Jalilian: Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, Lancaster, UK.
Galana Mamo Ayana: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Temesgen Ashine: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Elifaged Hailemeskel: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Yehenew Asmamaw Ebstie: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Eshetu Molla: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Endashaw Esayas: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Nigatu Negash: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Abena Kochora: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Muluken Assefa: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
Natnael Teferi: Public Health Emergency Management, Research, and Blood Bank Service Directorate, Oromia Region Health Bureau, Addis Ababa, Ethiopia.
Daniel Teshome: Public Health Emergency Management, Research, and Blood Bank Service Directorate, Dire Dawa City Administration Health Bureau, Dire Dawa, Ethiopia.
Alison M Reynolds: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
David Weetman: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
Anne L Wilson: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
Birhanu Kenate: Public Health Emergency Management, Research, and Blood Bank Service Directorate, Oromia Region Health Bureau, Addis Ababa, Ethiopia.
Martin J Donnelly: Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
Luigi Sedda: Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, Lancaster, UK.
Endalamaw Gadisa: Malaria and Neglected Tropical Disease, Armauer Hansen Research Institute, Addis Ababa, Ethiopia. endalamaw.gadisa@ahri.gov.et. ORCID
BACKGROUND: Despite consecutive decades of success in reducing malaria transmission, Ethiopia went off track towards its goal of malaria elimination by 2030, as outlined in the NMCP malaria strategy. Recent malaria outbreaks in Ethiopia are attributed to the emergence and spread of diagnostic and drug-resistant Plasmodium falciparum, increased insecticide resistance in major vectors and the spread of invasive Anopheles stephensi. The effects of the COVID-19 pandemic, environmental anomalies and internal conflicts have also potentially played a role in increasing malaria transmission. This study aimed to evaluate the contribution of environmental factors and An. stephensi to the spatiotemporal trends of recent malaria cases in Ethiopia. METHODS: Clinical malaria case data reported weekly between January 2013 and January 2023 were obtained from the Ethiopian Public Health Institute (EPHI), Addis Ababa. A negative binomial regression model was used to explain the variability and potential overdispersion in the weekly number of malaria cases reported across Ethiopian administrative zones. This model incorporated fixed effects for selected environmental factors and random effects to capture temporal trends, zone specific seasonal patterns, spatial trends at the zone level, and the presence of An. stephensi and its impact. RESULTS: Our negative binomial regression model highlighted 56% variability in the data and slightly more than half (55%) was due to environmental factors, while the remainder was captured by random effects. A significant nationwide decline in malaria risk was observed between 2013 and 2018, followed by a sharp increase in early 2022. Malaria risk was higher in western and northwestern zones of Ethiopia compared to other zones. Zone-specific seasonal patterns, not explained by environmental factors, were grouped into four clusters of seasonal behaviours. The presence of An. stephensi was not shown to have any significant impact on malaria risk. CONCLUSIONS: Understanding the spatial and temporal drivers of malaria transmission and therefore identifying more appropriate malaria control strategies are key to the success of any malaria elimination and eradication programmes in Ethiopia. Our study found that approximately 50% of malaria risk variability could be explained by environmental, temporal, and spatial factors included in the analysis, while the remaining variation was unexplained and may stem from other factors not considered in this study. This highlights the need for a better understanding of underlying factors driving local malaria transmission and outbreaks, to better tailor regional programmatic responses.
