Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders
Background Agricultural worksites are rarely targeted by malaria control programmes, yet may play a role in maintaining local transmission due to workers’ high mobility, low intervention coverage and occupational exposures.Methods A quasi-experimental controlled intervention study was carried out in...
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BMJ Publishing Group
2025-02-01
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| Series: | BMJ Global Health |
| Online Access: | https://gh.bmj.com/content/10/2/e015565.full |
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| author | Roly Gosling Adam Bennett Petrina Uusiku Henry Ntuku Bryan Greenhouse Jennifer L Smith Jerry O Jacobson Cara Smith-Gueye Francois Rerolle Ashley Morgan Burke Tabeth Mwema Keirstinne Turcios Justine Kulla Haikali Michael Lifasi Elodie Vajda Davis R Mumbengegwi |
| author_facet | Roly Gosling Adam Bennett Petrina Uusiku Henry Ntuku Bryan Greenhouse Jennifer L Smith Jerry O Jacobson Cara Smith-Gueye Francois Rerolle Ashley Morgan Burke Tabeth Mwema Keirstinne Turcios Justine Kulla Haikali Michael Lifasi Elodie Vajda Davis R Mumbengegwi |
| author_sort | Roly Gosling |
| collection | DOAJ |
| description | Background Agricultural worksites are rarely targeted by malaria control programmes, yet may play a role in maintaining local transmission due to workers’ high mobility, low intervention coverage and occupational exposures.Methods A quasi-experimental controlled intervention study was carried out in farming and cattle herding populations in northern Namibia to evaluate the impact of a targeted malaria intervention package. Eight health facility catchment areas in Zambezi and Ohangwena Regions were randomised to an intervention arm and eligible individuals within worksites in intervention areas received targeted drug administration with artemether-lumefantrine, mop-up indoor residual spraying and long-lasting insecticidal nets, combined with distribution of topical repellent in Zambezi Region. Impact on malaria outcomes and intervention coverage was evaluated over a single transmission season using pre-intervention and post-intervention cross-sectional surveys in a random subset of worksites and community incidence from passively detected cases. Entomological collections and residual efficacy assays on canvas and tarpaulin were conducted.Results Delivery of a single intervention round was associated with a reduction in the prevalence of malaria (OR 0.24, 95% CI 0.1 to 0.5; risk difference (RD) −6.0%, 95% CI −9.4 to –2.8). Coverage of at least one intervention increased (RD 51.6%, 95% CI 44.4 to 58.2) among the target population in intervention compared with control areas. This effect was largely driven by results in Zambezi Region, which also observed a decline in community incidence (−1.29 cases/1000 person-weeks, 95% CI −2.2 to –0.3). Residual efficacy of pirimiphos-methyl (Actellic) on tarpaulin and canvas was high at 24hours but declined to 44.6% at 4 months.Conclusion The study shows that targeted delivery of malaria interventions to cattle herders and agricultural workers at worksites has potential to impact local transmission. Findings highlight the need for further research on the role of key populations in Plasmodium falciparum transmission in Namibia.Trial registration number NCT04094727. |
| format | Article |
| id | doaj-art-ee9f942d01af4bcb849f69a5cfb971b1 |
| institution | DOAJ |
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| language | English |
| publishDate | 2025-02-01 |
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| spelling | doaj-art-ee9f942d01af4bcb849f69a5cfb971b12025-08-20T03:01:07ZengBMJ Publishing GroupBMJ Global Health2059-79082025-02-0110210.1136/bmjgh-2024-015565Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herdersRoly Gosling0Adam Bennett1Petrina Uusiku2Henry Ntuku3Bryan Greenhouse4Jennifer L Smith5Jerry O Jacobson6Cara Smith-Gueye7Francois Rerolle8Ashley Morgan Burke9Tabeth Mwema10Keirstinne Turcios11Justine Kulla Haikali12Michael Lifasi13Elodie Vajda14Davis R Mumbengegwi15Malaria Elimination Initiative, University of California San Francisco, San Francisco, California, USAMalaria Elimination Initiative, University of California San Francisco, San Francisco, California, USANational Vector-Borne Diseases Control Program, Namibia Ministry of Health and Social Services, Windhoek, Khomas, NamibiaMalaria Elimination Initiative, University of California San Francisco, San Francisco, California, USADepartment of Medicine, University of California San Francisco, San Francisco, California, USAEpidemiology & Biostatistics, University of California San Francisco, San Francisco, California, USAMalaria Elimination Initiative, University of California San Francisco, San Francisco, California, USAMalaria Elimination Initiative, University of California San Francisco, San Francisco, California, USAMalaria Elimination Initiative, University of California San Francisco, San Francisco, California, USAUniversity of the Witwatersrand Johannesburg Faculty of Health Sciences, Johannesburg, Gauteng, South AfricaMultidisciplinary Research Services, University of Namibia, Windhoek, NamibiaDepartment of Medicine, University of California San Francisco, San Francisco, California, USAOhangwena Health Directorate, Republic of Namibia Ministry of Health and Social Services, Windhoek, Khomas, NamibiaZambezi Health Directorate, Republic of Namibia Ministry of Health and Social Services, Windhoek, Khomas, NamibiaMalaria Elimination Initiative, University of California San Francisco, San Francisco, California, USAMalaria Operational Research Program, Multidisciplinary Research Services, University of Namibia, Windhoek, Khomas, NamibiaBackground Agricultural worksites are rarely targeted by malaria control programmes, yet may play a role in maintaining local transmission due to workers’ high mobility, low intervention coverage and occupational exposures.Methods A quasi-experimental controlled intervention study was carried out in farming and cattle herding populations in northern Namibia to evaluate the impact of a targeted malaria intervention package. Eight health facility catchment areas in Zambezi and Ohangwena Regions were randomised to an intervention arm and eligible individuals within worksites in intervention areas received targeted drug administration with artemether-lumefantrine, mop-up indoor residual spraying and long-lasting insecticidal nets, combined with distribution of topical repellent in Zambezi Region. Impact on malaria outcomes and intervention coverage was evaluated over a single transmission season using pre-intervention and post-intervention cross-sectional surveys in a random subset of worksites and community incidence from passively detected cases. Entomological collections and residual efficacy assays on canvas and tarpaulin were conducted.Results Delivery of a single intervention round was associated with a reduction in the prevalence of malaria (OR 0.24, 95% CI 0.1 to 0.5; risk difference (RD) −6.0%, 95% CI −9.4 to –2.8). Coverage of at least one intervention increased (RD 51.6%, 95% CI 44.4 to 58.2) among the target population in intervention compared with control areas. This effect was largely driven by results in Zambezi Region, which also observed a decline in community incidence (−1.29 cases/1000 person-weeks, 95% CI −2.2 to –0.3). Residual efficacy of pirimiphos-methyl (Actellic) on tarpaulin and canvas was high at 24hours but declined to 44.6% at 4 months.Conclusion The study shows that targeted delivery of malaria interventions to cattle herders and agricultural workers at worksites has potential to impact local transmission. Findings highlight the need for further research on the role of key populations in Plasmodium falciparum transmission in Namibia.Trial registration number NCT04094727.https://gh.bmj.com/content/10/2/e015565.full |
| spellingShingle | Roly Gosling Adam Bennett Petrina Uusiku Henry Ntuku Bryan Greenhouse Jennifer L Smith Jerry O Jacobson Cara Smith-Gueye Francois Rerolle Ashley Morgan Burke Tabeth Mwema Keirstinne Turcios Justine Kulla Haikali Michael Lifasi Elodie Vajda Davis R Mumbengegwi Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders BMJ Global Health |
| title | Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders |
| title_full | Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders |
| title_fullStr | Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders |
| title_full_unstemmed | Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders |
| title_short | Targeting malaria in high-risk populations in low endemic regions in northern Namibia: a quasi-experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders |
| title_sort | targeting malaria in high risk populations in low endemic regions in northern namibia a quasi experimental controlled trial to reduce malaria in seasonal agricultural workers and cattle herders |
| url | https://gh.bmj.com/content/10/2/e015565.full |
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