The November-2023-March-2024 malaria epidemic in Zanzibar: a spatiotemporal epidemiological analysis

Frederike Kooiman; Mohamed Haji Ali; Michael Alifrangis; Shija Joseph Shija; Wahida Shirazi Hassan; Karin Linda Schiøler; Fatma Saleh

doi:10.1186/s12936-025-05507-2

The November-2023-March-2024 malaria epidemic in Zanzibar: a spatiotemporal epidemiological analysis

Frederike Kooiman, Mohamed Haji Ali, Michael Alifrangis, Shija Joseph Shija, Wahida Shirazi Hassan, Karin Linda Schiøler, Fatma Saleh

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

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Abstract

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.

Originalsprog	Engelsk
Artikelnummer	354
Tidsskrift	Malaria Journal
Vol/bind	24
Udgave nummer	1
Antal sider	14
ISSN	1475-2875
DOI	https://doi.org/10.1186/s12936-025-05507-2
Status	Udgivet - 2025

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title = "The November-2023-March-2024 malaria epidemic in Zanzibar: a spatiotemporal epidemiological analysis",

abstract = "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.",

keywords = "Humans, Malaria/epidemiology, Tanzania/epidemiology, Spatio-Temporal Analysis, Male, Adolescent, Adult, Young Adult, Female, Incidence, Epidemics/statistics & numerical data, Middle Aged, Child, Preschool, Child, Infant, Temperature, Aged",

author = "Frederike Kooiman and Ali, {Mohamed Haji} and Michael Alifrangis and Shija, {Shija Joseph} and Hassan, {Wahida Shirazi} and Schi{\o}ler, {Karin Linda} and Fatma Saleh",

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T1 - The November-2023-March-2024 malaria epidemic in Zanzibar

T2 - a spatiotemporal epidemiological analysis

AU - Kooiman, Frederike

AU - Ali, Mohamed Haji

AU - Alifrangis, Michael

AU - Shija, Shija Joseph

AU - Hassan, Wahida Shirazi

AU - Schiøler, Karin Linda

AU - Saleh, Fatma

PY - 2025

Y1 - 2025

N2 - 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.

AB - 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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KW - Malaria/epidemiology

KW - Tanzania/epidemiology

KW - Spatio-Temporal Analysis

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KW - Adolescent

KW - Adult

KW - Young Adult

KW - Female

KW - Incidence

KW - Epidemics/statistics & numerical data

KW - Middle Aged

KW - Child, Preschool

KW - Child

KW - Infant

KW - Temperature

KW - Aged

U2 - 10.1186/s12936-025-05507-2

DO - 10.1186/s12936-025-05507-2

M3 - Journal article

C2 - 41121104

SN - 1475-2875

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JO - Malaria Journal

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