Abdul Alim

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.

We compared the efficacy of three intervention packages for active case detection (ACD) of visceral leishmaniasis (VL)/post–kala-azar dermal leishmaniasis (PKDL) combined with sandfly control around an index case. The packages were 1) no kala-azar transmission activity involving indoor residual spraying (IRS) with deltamethrin, peri-domestic deployment of larvicide with temephos, and house-to-house search for cases; 2) fever camp (FC) plus durable wall lining (DWL) with deltamethrin; and 3) FC plus insecticide (deltamethrin) impregnated bed-nets (ITN) around an index case. Fever camp includes 1-day campaign at the village level to screen and diagnose VL, PKDL, leprosy, malaria, and tuberculosis among residents with chronic fever or skin disease. Efficacy was measured through yield of new cases, vector density reduction, and mortality at 1, 3, 6, 9, and 12 months following intervention. Fever camp + DWL was the most efficacious intervention package with 0.5 case detected per intervention, 79% reduction in vector density (incidence rate ratio [IRR] = 0.21, P = 0.010), and 95.1% (95% confidence interval: 93.4%, 96.8%) sandfly mortality at 12 months. No kala-azar transmission activity was efficacious for vector control (74% vector reduction, IRR = 0.26, P < 0.0001 at 9 months; and 84% sandfly mortality at 3 months), but not for case detection (0 case per intervention). Fever camp + ITN was efficacious in detection of VL/PKDL cases (0.43 case per intervention), but its efficacy for vector control was inconsistent. We recommend index case–based FC for ACD combined with DWL or IRS plus larvicide for sandfly control during the consolidation and maintenance phases of the VL elimination program of the Indian subcontinent.