Efficacy of PermaNet® 3.0 and PermaNet® 2.0 nets against laboratory-reared and wild Anopheles gambiae sensu lato populations in northern Tanzania

Abstract

BackgroundMosquitoes have developed resistance against pyrethroids, the only class of insecticides approved for use on long-lasting insecticidal nets (LLINs). The present study sought to evaluate the efficacy of the pyrethroid synergist PermaNet® 3.0 LLIN versus the pyrethroid-only PermaNet® 2.0 LLIN, in an East African hut design in Lower Moshi, northern Tanzania. In this setting, resistance to pyrethroid insecticides has been identified in Anopheles gambiae mosquitoes.MethodsStandard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area where there was presence of a population of highly pyrethroid-resistant An. arabiensis mosquitoes. All nets used were subjected to cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition and personal protection rate were compared between untreated nets, unwashed LLINs and LLINs that were washed 20 times.ResultsBoth washed and unwashed PermaNet® 2.0 and PermaNet® 3.0 LLINs had knockdown and mortality rates of 100% against a susceptible strain of An. gambiae sensu stricto. The adjusted mortality rate of the wild mosquito population after use of the unwashed PermaNet® 3.0 and PermaNet® 2.0 nets was found to be higher than after use of the washed PermaNet® 2.0 and PermaNet® 3.0 nets.ConclusionsGiven the increasing incidence of pyrethroid resistance in An. gambiae mosquitoes in Tanzania, we recommend that consideration is given to its distribution in areas with pyrethroid-resistant malaria vectors within the framework of a national insecticide-resistance management plan.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0220-z) contains supplementary material, which is available to authorized users.

Decreased bioefficacy of long-lasting insecticidal nets and the resurgence of malaria in Papua New Guinea

“…Most of these studies used LLINs dating back to 2012 and before, and showed very good bioefficacy of PermaNet® 2.0 [25][26][27][28][29]. In tests conducted in an African setting (Northern Tanzania), PermaNet® 2.0 from 2017 were reported to fulfil all requirements [30]. However in a recent report from Iran, PermaNet® 2.0 did not seem to fulfil bioefficacy requirements [31].…”

Piperonyl Butoxide: An Enhancing Arsenal for an Adomant Foe

“…The incorporation of a Synergistic effect of Piperonyl Butoxide (PBO) on roof and side panels of LLINs have improved the efficacy of LLINs against resistant mosquitoes [19][20][21][22]. It has a potency of increasing cuticular penetration of insecticides and increase mosquito susceptibility [23].…”

“…LLINs with PBO have shown more efficacy against pyrethroid resistant mosquitoes than nets with pyrethroids only [21]. Metabolic resistant is widely spread in malaria vectors across sub-Saharan Africa and PBO could enhance the performance of LLINs by increasing the susceptibility status of the vectors to pyrethroids [21,22]. PBO works by inhibiting the activity of enzymes in insect body [24].…”

“…PBO works by inhibiting the activity of enzymes in insect body [24]. However, incorporation of PBO synegist in LLINs, has been reported to restore the efficacy of pyrethroids in the areas with high pyrethroid resistant population [21,22]. The LLINs with PBO have proved to be safe and no any side effect for human beings [25][26][27].…”

“…Currently, LLINs have an improved synergistic effect of PBO on top or on top and all side panels for managemenet of insecticide resistance [20,22].…”