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Randomized Controlled Trial
. 2025 May 21;15(1):17709.
doi: 10.1038/s41598-025-02943-7.

A randomized controlled trial combining house screening and insecticide-treated nets reduces malaria transmission in northwestern Ethiopia

Aklilu K Belay  1   2 , Abebe Asale  3 , Catherine L Sole  2 , Abdullahi A Yusuf  2 , Baldwyn Torto  1   2 , Zewdu Abro  1 , Menale Kassie  1 , Clifford M Mutero  1   4 , David P Tchouassi  5
Affiliations
Randomized Controlled Trial

A randomized controlled trial combining house screening and insecticide-treated nets reduces malaria transmission in northwestern Ethiopia

Aklilu K Belay et al. Sci Rep. .

Abstract

House screening (HS) of doors, eaves, and windows using wire-mesh has demonstrated potential in the integrated vector management of malaria. However, limited epidemiological data are available to guide its implementation across different ecological settings. In a 16-month randomized controlled trial (follow-up period) conducted across three agroecological areas (dry mountain, plateau highland, and semi-arid) in Jabi Tehnan district, northwestern Ethiopia, treatment houses were equipped with HS combined with insecticide-treated nets (ITNs), while control houses received ITNs only. The intervention led to a significant 2.3-fold reduction in indoor malaria vector density, the primary entomologic outcome, largely influenced by An. gambiae s.l. mosquitoes. Fewer blood-fed mosquitoes were found in screened houses, indicating reduced human bites, which translated to six-fold decline in malaria prevalence (0.7%), the primary epidemiologic outcome, compared to control houses (4.3%). In contrast, Plasmodium sporozoite infection rates showed no differences between screened and control houses or agroecological zones, with An. arabiensis and An. funestus s.l. identified as the primary vectors. A modest protective effectiveness (22.6%) was observed, based on the estimated entomological inoculation rate of 0.24 and 0.31 infectious bites/person/night in screened and control houses, respectively, with no variation by agroecology. Despite the synergistic impact of HS with existing ITNs in reducing vector densities, human bite rates, and household malaria prevalence, sustained transmission persisted, partly due to the presence of highly competent vectors such as An. funestus s.l. which had an overall sporozoite rate of 68%. Future research should explore the interactions between vector behavioral adaptations, ecological and social factors contributing to residual transmission, even with seemingly effective control measures.

Keywords: Plasmodium infection; Entomology; Epidemiology; Malaria; Randomized controlled trial.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: A review of the study protocol and ethical approval were given by the Regional Public Health Research Ethics Review Committee/RERC/(Ref. No: H/R/T/T/D/5/3) from Amhara Public Health Research Institute, Ethiopia, and confirm that all methods were performed in accordance with the relevant guidelines and regulations. The research activity was started by providing information about the whole objective of the study to the community and consensus obtained from household owners for the project-related activities done with the directions given by local stakeholders. Further written informed consent was obtained from all subjects and/or their legal guardian(s). Competing interests: The authors declare no competing interests. Trial registration: The study protocol was registered online on May 28, 2020, with the Pan African Clinical Trials Registry (PACTR) at www.pactr.org. The registration number assigned to the protocol is PACTR202006878245287. The Trial’s methodology was also discussed by Asale et al.9.

Figures

Fig. 1
Fig. 1
Map of the study area in Jabi Tehnan district, Amhara Region Ethiopia, showing the three major zones (Semi-arid, Plateau and Dry mountain highlands) and the villages (red dots) where sampling was conducted between July 2020 and October 2021.
Fig. 2
Fig. 2
Impact of house screening on cumulative indoor anopheline densities in control and screened houses by agroecology in Jabi Tehnan District, Northwestern Ethiopia.
Fig. 3
Fig. 3
Agroecological differences in anopheline indoor densities in Jabi Tehnan District, Northwestern Ethiopia.
Fig. 4
Fig. 4
Impact of house screening on blood feeding proportions and host range among Anopheles mosquitoes in Jabi Tehnan District, Northwestern Ethiopia.
See this image and copyright information in PMC

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