Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar

Abstract Background The Zanzibar Malaria Elimination Programme relies on insecticide-treated nets as the principal vector control method, supplemented by reactive focal indoor residual spraying. Despite the success, local malaria transmission persists, and the underlying reasons for sustained transm...

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Main Authors: Bakar Khatib, Juma Mcha, Zamzam Pandu, Makame Haji, Makame Hassan, Huba Ali, Ramla Mrisho, Kali Abdallah, Ali Ali, Khadija Ali, Talib Said, Safia Mohamed, Humphrey Mkali, Said Mgata, Stella Makwaruzi, Michael Gulaka, Geofrey Makenga, Sigsbert Mkude, Victoria Githu, Victor Mero, Naomi Serbantez, Sarah-Blythe Ballard, Adeline Chan, Shija Joseph Shija, Nicodem J. Govella
Format: Article
Language:English
Published: BMC 2025-03-01
Series:Malaria Journal
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Online Access:https://doi.org/10.1186/s12936-025-05333-6
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author Bakar Khatib
Juma Mcha
Zamzam Pandu
Makame Haji
Makame Hassan
Huba Ali
Ramla Mrisho
Kali Abdallah
Ali Ali
Khadija Ali
Talib Said
Safia Mohamed
Humphrey Mkali
Said Mgata
Stella Makwaruzi
Michael Gulaka
Geofrey Makenga
Sigsbert Mkude
Victoria Githu
Victor Mero
Naomi Serbantez
Sarah-Blythe Ballard
Adeline Chan
Shija Joseph Shija
Nicodem J. Govella
author_facet Bakar Khatib
Juma Mcha
Zamzam Pandu
Makame Haji
Makame Hassan
Huba Ali
Ramla Mrisho
Kali Abdallah
Ali Ali
Khadija Ali
Talib Said
Safia Mohamed
Humphrey Mkali
Said Mgata
Stella Makwaruzi
Michael Gulaka
Geofrey Makenga
Sigsbert Mkude
Victoria Githu
Victor Mero
Naomi Serbantez
Sarah-Blythe Ballard
Adeline Chan
Shija Joseph Shija
Nicodem J. Govella
author_sort Bakar Khatib
collection DOAJ
description Abstract Background The Zanzibar Malaria Elimination Programme relies on insecticide-treated nets as the principal vector control method, supplemented by reactive focal indoor residual spraying. Despite the success, local malaria transmission persists, and the underlying reasons for sustained transmission remain unclear, yet critical to optimizing vector control for elimination. Entomological characterization of transmission dynamics was conducted to identify the gaps with existing interventions and opportunities for complementary interventions. Methods Adult malaria vectors were collected monthly for two consecutive nights at ten sentinel sites (6 Unguja, 4 Pemba) from October 2022 to September 2023. Hourly indoor and outdoor human landing catch method was used for collecting mosquitoes from 18:00 to 06:00 h. Results Anopheles arabiensis was the predominant malaria vector species across all the sentinel sites, except in the urban district of Unguja, where Anopheles gambiae sensu stricto was predominant. Malaria parasite-infected An. arabiensis bites were distributed disproportionately between indoors (n = 4), 22:00 to 02:00 h, and outdoors (n = 10) earlier in the evenings, 1800 to 2100 h. Conclusion The outdoor catches of malaria-parasite infected mosquitoes before typical sleeping hours highlight the potential risk of human exposure to outdoor transmission.
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spelling doaj-art-a2c5589f7cd7460ab7ba04486c8d647c2025-08-20T03:41:40ZengBMCMalaria Journal1475-28752025-03-012411910.1186/s12936-025-05333-6Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in ZanzibarBakar Khatib0Juma Mcha1Zamzam Pandu2Makame Haji3Makame Hassan4Huba Ali5Ramla Mrisho6Kali Abdallah7Ali Ali8Khadija Ali9Talib Said10Safia Mohamed11Humphrey Mkali12Said Mgata13Stella Makwaruzi14Michael Gulaka15Geofrey Makenga16Sigsbert Mkude17Victoria Githu18Victor Mero19Naomi Serbantez20Sarah-Blythe Ballard21Adeline Chan22Shija Joseph Shija23Nicodem J. Govella24Zanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarPMI Dhibiti (Control) Malaria Project, Population Services InternationalPMI Dhibiti (Control) Malaria Project, Population Services InternationalPMI Dhibiti (Control) Malaria Project, Population Services InternationalPMI Dhibiti (Control) Malaria Project, Population Services InternationalPMI Dhibiti (Control) Malaria Project, Population Services InternationalPMI Dhibiti (Control) Malaria Project, Population Services InternationalEnvironmental Health and Ecological Sciences Department, Ifakara Health InstituteEnvironmental Health and Ecological Sciences Department, Ifakara Health InstituteU.S. President’s Malaria Initiative, U. S. Agency for International DevelopmentU.S. President’s Malaria Initiative, US Centers for Disease Control and PreventionEntomology Branch, Division of Parasitic Diseases and Malaria, U.S. President’S Malaria Initiative, U.S. Centers for Disease Control and PreventionZanzibar Malaria Elimination Program, Ministry of Health of ZanzibarPMI Dhibiti (Control) Malaria Project, Population Services InternationalAbstract Background The Zanzibar Malaria Elimination Programme relies on insecticide-treated nets as the principal vector control method, supplemented by reactive focal indoor residual spraying. Despite the success, local malaria transmission persists, and the underlying reasons for sustained transmission remain unclear, yet critical to optimizing vector control for elimination. Entomological characterization of transmission dynamics was conducted to identify the gaps with existing interventions and opportunities for complementary interventions. Methods Adult malaria vectors were collected monthly for two consecutive nights at ten sentinel sites (6 Unguja, 4 Pemba) from October 2022 to September 2023. Hourly indoor and outdoor human landing catch method was used for collecting mosquitoes from 18:00 to 06:00 h. Results Anopheles arabiensis was the predominant malaria vector species across all the sentinel sites, except in the urban district of Unguja, where Anopheles gambiae sensu stricto was predominant. Malaria parasite-infected An. arabiensis bites were distributed disproportionately between indoors (n = 4), 22:00 to 02:00 h, and outdoors (n = 10) earlier in the evenings, 1800 to 2100 h. Conclusion The outdoor catches of malaria-parasite infected mosquitoes before typical sleeping hours highlight the potential risk of human exposure to outdoor transmission.https://doi.org/10.1186/s12936-025-05333-6outdoor bitingmalaria eliminationentomological characterizationmalaria vectormalaria transmissionmalaria elimination in Zanzibar
spellingShingle Bakar Khatib
Juma Mcha
Zamzam Pandu
Makame Haji
Makame Hassan
Huba Ali
Ramla Mrisho
Kali Abdallah
Ali Ali
Khadija Ali
Talib Said
Safia Mohamed
Humphrey Mkali
Said Mgata
Stella Makwaruzi
Michael Gulaka
Geofrey Makenga
Sigsbert Mkude
Victoria Githu
Victor Mero
Naomi Serbantez
Sarah-Blythe Ballard
Adeline Chan
Shija Joseph Shija
Nicodem J. Govella
Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar
Malaria Journal
outdoor biting
malaria elimination
entomological characterization
malaria vector
malaria transmission
malaria elimination in Zanzibar
title Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar
title_full Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar
title_fullStr Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar
title_full_unstemmed Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar
title_short Early evening outdoor biting by malaria-infected Anopheles arabiensis vectors threatens malaria elimination efforts in Zanzibar
title_sort early evening outdoor biting by malaria infected anopheles arabiensis vectors threatens malaria elimination efforts in zanzibar
topic outdoor biting
malaria elimination
entomological characterization
malaria vector
malaria transmission
malaria elimination in Zanzibar
url https://doi.org/10.1186/s12936-025-05333-6
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