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. 2025 Jul 17;24(1):235.
doi: 10.1186/s12936-025-05351-4.

Malaria epidemics and its drivers in Uganda in 2022

Maru W Aregawi  1 , Catherine Maiteki  2 , John C Rek  2 , Bosco Agaba  2   3 , Charles Katureebe  4 , Mansour Ranjbar  4 , Chunzhe Zhang  5 , Samson Kiware #  6 , Jimmy Opigo #  2
Affiliations

Malaria epidemics and its drivers in Uganda in 2022

Maru W Aregawi et al. Malar J. .

Abstract

Background: In Uganda, malaria is a year-round health threat, with transmission intensity varying across regions. Despite ongoing intensified interventions, an unprecedented malaria resurgence in early 2022 affected several districts, prompting a swift response from the National Malaria Control Division (NMCD). This study aims to assess the scale and underlying causes of the epidemics, quantify the excess cases and deaths, and propose targeted prevention and response strategies.

Methods: District Health Information System (DHIS2) data from 2017 to 2022 were analysed. A 75th percentile threshold from 2017 to 2021 was used to define true malaria epidemics and compare them to the suspected 2022 epidemic. Excess cases, admissions, and deaths were quantified using area under the curve (AUC) calculations. The level of epidemics was compared across districts with Indoor Residual Spraying (IRS) and Integrated Community Case Management (iCCM) interventions. Precipitation data from multiple sources were used to evaluate rainfall patterns and their impact on malaria epidemics.

Results: Malaria cases were lowest in 2018 but rose by 31% in 2022 compared to the 2017-2021 3rd quartile. Sixty-four of 146 districts experienced epidemics, with 4 facing persistent epidemics year-round. The 2022 epidemic accounted for 3,379,309 (95% CI 1,553,714, 5,339,709) total excess outpatient malaria cases (confirmed and presumed), 3,018,920 (95% CI 1,321,951, 4,661,201) excess confirmed cases, 149,789 (95% CI 66,029, 235,743) excess inpatient cases. Paradoxically, more epidemics occurred in IRS and iCCM districts. Precipitation patterns were consistent across years and were insignificantly correlated with the 2022 epidemic. Provinces with bimodal rainfall patterns were more prone to epidemics, while unimodal regions had fewer epidemics but higher incidence rates. Rainfall lagged by two months (Lag 2) significantly increased malaria incidence (p < 0.01), with each millimetre of rainfall two months prior associated with 13.4 additional malaria cases.

Conclusion: The 2022 malaria epidemic affected 64 districts, with over 3.3 million excess cases and nearly 150,000 excess admissions. Gaps in IRS, iCCM, and intervention coverage, along with minimal rainfall correlation and high vulnerability in bimodal regions, highlight the need for better surveillance, sustainable funding, and tailored responses. While climate was not the main driver, programmatic deficiencies, vector composition shift, reduced efficacy of insecticides, coverage and effectiveness of the interventions likely fueled the epidemic. Strengthening epidemic preparedness, response, and investment will be crucial to preventing future outbreaks and achieving long-term malaria control in Uganda.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Map of Uganda showing 2022 and former IRS and iCCM-districts
Fig. 2
Fig. 2
Trends in outpatient Malaria Cases, Testing, and Positivity Rates Across All Ages, Uganda 2017–2022
Fig. 3
Fig. 3
Trends in Malaria Cases, Inpatients, and Deaths vs. Non-Malaria Metrics, Uganda 2017–2022
Fig. 4
Fig. 4
Outpatient malaria cases per 1000 population and inpatient malaria cases per 1000 population, 2022
Fig. 5
Fig. 5
a Monthly outpatient malaria cases in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). b Monthly inpatient malaria cases in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). c Monthly malaria deaths in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). d Monthly Test Positivity Rate (TPR) in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). e Monthly outpatient malaria and inpatient incidence in 2022 vs. 2017–2021 3rd quartile thresholds by age group, Uganda
Fig. 5
Fig. 5
a Monthly outpatient malaria cases in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). b Monthly inpatient malaria cases in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). c Monthly malaria deaths in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). d Monthly Test Positivity Rate (TPR) in 2022 vs. 2017–2021 3rd quartile thresholds* by age group, Uganda (*2019 values removed). e Monthly outpatient malaria and inpatient incidence in 2022 vs. 2017–2021 3rd quartile thresholds by age group, Uganda
Fig. 6
Fig. 6
District-level differences in malaria cases and incidence: 2022 vs. 2017–2021 3rd quartile thresholds. a Relative difference of confirmed malaria cases b Absolute difference of incidence of malaria cases
Fig. 7
Fig. 7
National trends of test positivity rate (TPR) in 2022 compared to 2017–2021* thresholds in IRS and iCCM districts (*threshold doesn’t include 2019 values)
Fig. 8
Fig. 8
National trends of outpatient malaria cases in 2022 compared to 2017–2021 thresholds in IRS and iCCM districts
Fig. 9
Fig. 9
National trends of malaria inpatients in 2022 compared to 2017–2021 thresholds in IRS and iCCM districts
Fig. 10
Fig. 10
National Malaria Death Trends in 2022 vs. 2017–2021 Thresholds in IRS and iCCM Districts
Fig. 11
Fig. 11
National average monthly rainfall vs malaria cases (outpatient) 2017–2022
Fig. 12
Fig. 12
Scatterplot of monthly rainfall from Uganda National Meteorological Authority (UNMA) vs. CHIRPS, 2017–2022
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References

    1. United Nations Population Fund. https://www.unfpa.org/data/world-populat.... Accessed 2 Oct 2024.
    1. Uganda Malaria Indicator Survey (UMIS). 2009. https://dhsprogram.com/pubs/pdf/MIS6/MIS6.pdf. Accessed 2 Oct 2024.
    1. Uganda Malaria Indicator Survey (UMIS) 2014–15. https://dhsprogram.com/pubs/pdf/mis21/mis21.pdf. Accessed 19 Nov 2024.
    1. Uganda National Household Survey 2018–2019. https://www.ubos.org/wp-content/uploads/publications/09_2021Uganda-Natio.... Accessed 19 Nov 2024.
    1. Uganda National Malaria Control Division (NMCD), Uganda Bureau of Statistics (UBOS), and ICF. 2020. Uganda Malaria Indicator Survey 2018–19. Kampala, Uganda, and Rockville, Maryland, USA: NMCD, UBOS, and ICF.

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