Advancing Spatial Repellents for Malaria Control: Effectiveness and cost-effectiveness of a spatial repellent under operational use in Northern Uganda: study protocol for a cluster randomized controlled trial

Abstract

Background: Spatial Repellents (SRs) have been widely used for the prevention of mosquito bites, and preliminary findings suggest efficacy against both malaria (1) and Aedes-borne viruses (2)but their effectiveness in reducing mosquito borne diseases under operational use has never been evaluated. SRs have the potential of being critical tools in the prevention of mosquito borne diseases in contexts where typical vectors control strategies, such as Insecticide-Treated Nets (ITNs) and indoor residual spraying, are inaccessible or underutilized such as among displaced persons or in emergency relief settings. Methods: Children will be enrolled in 3 separate cohorts to establish effectiveness of SRs in reducing malaria infection in different distribution channels. One cohort will estimate the direct effect of the SR distributed through a reference channel (study personnel distribution). The two remaining cohorts will estimate the protection of the SR distributed through a voucher channel and Village Health Team channel. Cohorts will be followed twice a month (approximately every 15 days): during the first scheduled household visit in the month, a blood sample will be taken for malaria rapid diagnostic test (Monthly Visit #1); and, during the second scheduled household visit, a blood sample will only be taken if the participant has a recent history of fever (Monthly Visit #2). The incidence of malaria in each cohort will be estimated and compared to the reference cohort to determine the benefit of using a SR in an area with high, year-round transmission of malaria. Discussion: This study will address the knowledge gap of whether or not SRs are effective in reducing human malaria disease in humanitarian assistance and emergency response settings in sub-Saharan Africa where underlying transmission rates are historically high and ITNs may or may not be widely deployed. This research will inform policy makers on whether to recommend SRs as a means to further reduce malaria transmission for such operational programs. Trial Registration: ClinicalTrials.gov NCT06122142, registered November 8, 2023.