Pigeon, O. | Search bioRxiv

bioRxiv2023

PermaNet(R) Dual, a new deltamethrin-chlorfenapyr mixture net, shows improved efficacy against pyrethroid-resistant Anopheles gambiae sensu lato in southern Benin

Pyrethroid-chlorfenapyr nets have demonstrated improved entomological and epidemiological impact in trials across Africa. This is driving increased demand for this novel net class in malaria endemic countries. PermaNet(R) Dual is a new deltamethrin-chlorfenapyr net developed by Vestergaard Sarl to provide more options to malaria control programmes. We performed an experimental hut trial to evaluate the efficacy of PermaNet(R) Dual against wild, free-flying pyrethroid-resistant Anopheles gambiae sensu lato in Cove, Benin. PermaNet(R) Dual induced superior levels of mosquito mortality compared to a pyrethroid-only net and a pyrethroid-piperonyl butoxide net both when unwashed (77% with PermaNet(R) Dual vs. 23% with PermaNet(R) 2.0 and 56% with PermaNet(R) 3.0, p<0.001) and after 20 standardised washes (75% with PermaNet(R) Dual vs. 14% with PermaNet(R) 2.0 and 30% with PermaNet(R) 3.0, p<0.001). Using a provisional non-inferiority margin defined by the World Health Organisation, PermaNet(R) Dual was also non-inferior to a pyrethroid-chlorfenapyr net that has demonstrated improved public health value (Interceptor(R) G2), for vector mortality (79% vs. 76%, OR=0.854, 95% CIs: 0.703-1.038) but not for blood-feeding protection (35% vs. 26%, OR=1.445, 95% CIs: 1.203-1.735). PermaNet(R) Dual presents an additional option of this highly effective net class for improved control of malaria transmitted by pyrethroid-resistant mosquitoes.

zoology↗

bioRxiv2017

Small-scale field testing of Alpha-cypermethrin water-dispersible granules in comparison with the recommended wettable powder formulation for indoor residual spraying against malaria vectors in Benin

BackgroudPyrethroids are the most common class of insecticide used worldwide for indoor residual spraying (IRS) against malaria vectors. Water-dispersible granules (WG) are a pyrethroid formulation to be applied after disintegration and dispersion in water with less risks of inhalation than using the usual wettable powder (WP) formulation. The objective of this small-scale field study was to evaluate efficacy and duration of insecticidal action of a new alpha-cypermethrin WG (250g a.i./Kg) against susceptible Anopheles gambiae in comparison with the WHO reference product (alpha-cypermethrin WP, 50g a.i./Kg) on the most common indoor surfaces in Benin.\n\nMethodsBoth formulations were applied at two target-dose concentrations in houses made of mud and cement in the Tokoli village in southern Benin. We measured the applied dose of insecticide by chemical analysis of filter paper samples collected from the sprayed inner walls. We recorded An. gambiae mortality and knock-down rates every 15 days during 6 months using standard WHO bioassays.\n\nResultsThe alpha-cypermethrin WG formulation did not last as long as the WP formulation on both surfaces. The difference is higher with the 30mg/m2 concentration for which the WP formulation reached the 80% mortality threshold during 2 months on the mud-plastered walls (3 months on cement) whereas the WG formulation last only one month (2 months on cement).\n\nConclusionsThe new WG formulation has a shorter efficacy than the WHO recommended WP formulation. In this trial, both the WG and WP formulations had low durations of efficacy that would need at least two rounds of spray to cover the entire transmission season.

epidemiology↗