Bio-efficacy of DuraNet® long-lasting insecticidal nets against wild populations of Anopheles arabiensis in experimental huts

Abstract

BackgroundMosquitoes have developed resistance to multiple classes of insecticides for malaria vector control. A new generation of long-lasting insecticidal bed nets (LLINs) has been developed with increased efficacy against these resistant mosquitoes. The present study therefore evaluated the efficacy of the pyrethroid-based LLINs, DuraNet versus PermaNet 3.0, in an Eastern Africa hut design in Magugu in northern Tanzania where mosquitoes’ population higher proportion (69.3%) has been identified as Anopheles gambiae s.l.MethodsStandard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area with high populations of Anopheles arabiensis. All nets used were subjected to laboratory cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition, and personal protection rate were compared between untreated nets, unwashed LN, and LN that were washed 20 times.ResultsStandard WHO laboratory bioefficacy evaluations of DuraNet and PermaNet® 3.0 which were untreated, washed, or 20 times washed showed optimal knockdown and mortality for both net types against a susceptible strain of An. arabiensis. In standard experimental hut evaluations, the blood feeding inhibition for PermaNet® 3.0 unwashed and washed was 82.4% (76.3–88.6%) to 91.5% (84.1–98.8%) while for DuraNet was 98.3% (97.0–99.5%) to 96.0% (94.1–88.2%) respectively. The DuraNet LLINs showed a significantly higher killing effect than the other treatment of 90.0% (86.1–94.2%) and 94.0% (90.2–97.9%) for unwashed and washed nets respectively. No significant difference in deterrence or induced exophily was detected between the treatment arms. There were no adverse effects reported among sleepers in the experimental huts.ConclusionThe findings of this study indicate that the pyrethroid-based net DuraNet LLINs attained required efficacy when evaluated against wild population of An. arabiensis from Northern Tanzania. This adds value to the existing vector control tool box which gives community wider choice for vector control.

Bio-efficacy and wash resistance of MAGNet long-lasting insecticidal net against wild populations of Anopheles funestus in experimental huts in Muheza, Tanzania

“…The positive control nets (DuraNet) had protective efficacy of 40.4% before washing, which dropped to 2.6% after 20 washes. This sharp decline on protection efficacy was contrary to the previous study [8]. The data gathered from India showed that MAGNet had the highest blood-feeding inhibition, ranging from 43.3 to 48.1%, which was comparatively better than that in Muheza [27]; the study conducted in M’bé, Côte d’Ivoire had feeding inhibition of 40% for MAGNet which is lower than the Tanzania and India sites [26].…”

“…The low mortality of wild population of mosquitoes observed in the Muheza study site is suggested to be attributed to high resistance frequency observed in wild populations in previous findings [33, 34]. Due to the main effect of resistance, the most important measures of evaluated LLIN strength was recorded in terms of personal protection and killing effect outcomes [8, 35].…”

“…gambiae s.l. in Magugu, Moshi and Muheza [7, 8]. Other studies conducted in M’bé, Côte d’Ivoire showed the deterrence with MAGNet washed and unwashed to be higher than in control [26], while a study in India with MAGNet washed 25 times was not statistically different from other nets when compared in deterring mosquitoes from the huts [27].…”

“…In this study, the blood-feeding inhibition ranged between 0 and 58.1% for MAGNet unwashed and washed, respectively, compared to control. In a previous study conducted in Umbugweland using DuraNet, DuraNet had protection efficiency of 96.0 to 98.3% for 20 times washed and unwashed nets, respectively [8]. The huge variation in protection feeding inhibition might be due to high resistance level among wild population of An.…”

“…LLINs are the most effective and feasible means of preventing malaria transmission in sub-Saharan Africa with a physical and chemical barrier [7–10]. With good LLIN technology, insecticidal efficacy can be maintained against anopheline mosquitoes for at least 3 years without need for further retreatment [8–11]. The demand for LLINs has attracted the interest of several pesticide companies to produce new brands of LLINs [1, 12, 13].…”