Trapping and killing performance of a PermaNet 2.0 hybrid mosquito trapping bednet: an experimental hut evaluation

Abstract

Background: Despite the huge global effort , there has been an increase in malaria morbidity and mortality in sub-Saharan Africa since 2015, from 212 million cases and 429,000 deaths in 2015 to 241 million cases and 627,000 deaths in 2020 mainly because of resistance to insecticide. Therefore, advancing innovative approaches is the only sustainable way to fight malaria.

Methods: Taking advantage of the behavior of mosquitoes around the net, which is almost 70-90% concentrated on the roof, we have developed a two-compartment mosquito bednet, the so-called T-Net for mass mosquito trapping and killing. In the current study, we investigated in an experimental hut trial, the efficacy of trapping-long-lasting insecticide-treated nets (T-LLINs) against Anopheles gambiae s.l. in an insecticide resistance context. Five different arms have been considered in this study including three positive control arms e.g. PermaNet 2.0 LLIN, Tsara boost LLIN and Interceptor generation 2 (IG2) LLIN), one negative control arm using insecticide-free bednet, and one candidate arm using a hybrid-treated trapping bednet made with PermaNet 2.0 LLIN mounted with an insecticide-free compartment (T-LLIN).

Results: The highest average daily mortality was recorded with the T-LLIN. In total, 678 mosquitoes were killed by T-LLIN among the 760 collected, i.e. 89.2%. Out of these, 317 were found in the trap compartment, representing 46.75% of mortality directly attributable to the mechanical effect of this net. This added value made it possible to quantify the increased in the killing effect that this net would have over the positive control arms: this would be 58.5% higher than the killing effect of PN2.0, 38% higher than that of Tsara boost and 31.5% higher than that of IG2.

Conclusion: The current study shows potential to maximize the efficiency of the WHO-recommended LLINs by an addition of an insecticide-free trap compartment on top of the net.

Keywords: Insecticide Resistance Management; Malaria Vector Control; Mosquito Trapping Long Lasting Insecticidal Bednet.

Figure 1.. Average number of mosquitoes killed per day for the PN2 T-LLIN compared with PN2.0 only pyrethroid LLIN.

Figure 2.. Average number of mosquitoes killed per day for the PN2 T-LLIN compared with Tsara boost PBO-pyrethroid LLIN.

Figure 3.. Average number of mosquitoes killed per day for the PN2 T-LLIN compared with IG2 pyrrole-pyrethroid LLIN.

Figure 4.. Increased killing effect of T-LLIN (PN2.0-Trapping bednet) over PN2.0, Tsara boost (PBO net) and IG2.

The increased killing effect of T-LLIN over other LLINs tested was estimated as follow: Killing effect (%) = 100 x [(K _T-LLIN – K _Un) - (K _LLIN – K _Un)] / T _Un, where K _T-LLIN is the number of mosquitoes killed in the huts with T-LLIN, K _LLIN is the number of mosquitoes killed in the huts with the LLIN, K _{Un LLIN} is the number of mosquitoes killed in the untreated huts and T _Un, is the total number of mosquitoes collected from the huts with untreated net.