Field efficacy and acceptability of PermaNet® 3.0 and OlysetNet® in Kinshasa, Democratic Republic of the Congo

Abstract

Background & objectives: Insecticide resistance in mosquitoes at Kinshasa may jeopardize the efficacy and usage of long-lasting insecticidal nets (LLINs). Entomological impact, user acceptance and bioefficacy of a combination LLIN (PermaNet® 3.0) and a standard LLIN (OlysetNet®) were evaluated at two sites in Kinshasa characterized by high densities of either Anopheles gambiae s.s. (Kindele) or Culex spp (Kimbangu).

Methods: Insecticide susceptibility (permethrin, deltamethrin, bendiocarb, propoxur and DDT) was determined via tube tests and bottle assays. Entomological impact of unwashed and washed LLINs and untreated nets was assessed via Latin square, based on rotation of nets and their users through selected houses at each site. User acceptability was evaluated through interviews using a questionnaire and net bioefficacy was measured via cone bioassays with field-derived An. gambiae s.s.

Results: The An. gambiae s.s. population from Kindele was resistant to DDT and permethrin with mortality rate of 27.3 and 75.8%, respectively, and kdr mutations (L1014F) plus suspected metabolic resistance. The Culex spp population was resistant to all five insecticides tested. No differences in entomological indices were observed for the five net treatments, but bioefficacy against An. gambiae was significantly higher for unwashed and washed PermaNet 3.0 (100 and 71% mortality) than for OlysetNet (56 and 36%). Householders reported a good sleep most often when using unwashed and washed PermaNet (94 and 88%) and least often with unwashed OlysetNet (46%).

Interpretation & conclusion: High bioefficacy via cone bioassays against an An. gambiae s.s. population with kdr and suspected metabolic resistance was observed with PermaNet 3.0. Lower biting rates and a higher chance of a good night of sleep were reported when using PermaNet 3.0 compared to OlysetNet.