The November-2023-March-2024 malaria epidemic in Zanzibar: a spatiotemporal epidemiological analysis
Frederike Kooiman1,2, Mohamed Haji Ali3, Michael Alifrangis4,5
1School of Global Health, University of Copenhagen, Copenhagen, Denmark. f.kooiman@aighd.org.
Background:
In Zanzibar, malaria epidemiology has changed within the past 10 years, from focal, near-elimination transmission to recurrent and more widespread outbreaks. The observed changes culminated in a large-scale epidemic between November 2023 and March 2024 including 23,569 confirmed malaria cases.
Methods:
This study investigated the epidemiological characteristics of the 21-week outbreak by characterizing the risk profile of affected individuals, identifying malaria hotspots across space and time, and determining the association between malaria incidence and precipitation and temperature.
Results:
Males, individuals aged 15-35, urban residents, and those reporting to not sleep under insecticide-treated nets had a higher malaria risk. One significant space-time cluster was identified in the urban southwest of Unguja. The weekly number of malaria cases was significantly associated with the average weekly temperature, with an 8-week lag time.
Conclusions:
The results indicate a serious setback in the pursuit of malaria elimination in Zanzibar and call for intensified malaria interventions targeting high-risk populations.
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