Comparison of Novel Sandfly Control Interventions: A Pilot Study in Bangladesh

In this pilot comparative study, we investigated and compared the effects of existing vector control tools on sandfly densities and mortality to inform and support the National Kala-azar Elimination Program (NKEP). The interventions included insecticidal wall painting (IWP), reduced-coverage insecticidal durable wall lining (DWL), insecticide-impregnated bednets (ITN), and indoor residual spraying with deltamethrin (IRS). Sakhua union with seven villages was the study area, which was the most highly endemic visceral leishmaniasis union in Trishal upazila, Bangladesh. Each cluster containing the different interventions included approximately 50 households. Study methods included random selection of clusters, collection of sandfly by CDC light trap and manual aspirator to determine sandfly density, and sandfly mortality determined by WHO cone bioassay test. Trained field research assistants interviewed household heads using structured questionnaires for sociodemographic information, as well as safety and acceptability of the interventions. Descriptive and analytical statistical methods measured interventions' effect and its duration on sandfly density reduction and mortality. We measured the relative efficacy of IWP on sandfly control against DWL, ITN, and IRS by the difference-in-difference regression model. We found that existing interventions were effective and safe for sandfly control with different duration of effect and acceptability. The relative efficacy of IWP for sandfly reduction varied by -59% to -91%, -75% to -81%, and -30% to -104% compared with DWL, ITN, and IRS, respectively, at different time points during the 12-month follow-up. These study results will guide the NKEP for selection of sandfly control tool(s) in its subsequent consolidation and maintenance phases.