Community-level impacts of spatial repellents for control of diseases vectored by Aedes aegypti mosquitoes

Abstract

Spatial repellents (SRs) reduce human-mosquito contact by preventing mosquito entrance into human-occupied spaces and interfering with host-seeking and blood-feeding. A new model to synthesize experimental data on the effects of transfluthrin on Aedes aegypti explores how SR effects interact to impact the epidemiology of diseases vectored by these mosquitoes. Our results indicate that the greatest impact on force of infection is expected to derive from the chemical's lethal effect but delayed biting and the negative effect this may have on the mosquito population could elicit substantial impact in the absence of lethality. The relative contributions of these effects depend on coverage, chemical dose, and housing density. We also demonstrate that, through an increase in the number of potentially infectious mosquito bites, increased partial blood-feeding and reduced exiting may elicit adverse impacts, which could offset gains achieved by other effects. Our analysis demonstrates how small-scale experimental data can be leveraged to derive expectations of epidemiological impact of SRs deployed at larger scales.

The entomological impact of passive metofluthrin emanators against indoor Aedes aegypti: A randomized field trial

“…Traditional models of vectorial capacity demonstrate that the greatest epidemiological impacts of vector control tools occur when both adult survival and biting rates are affected [50]. However, there are considerable subtleties involved in predicting the effect of volatile pyrethroids that disrupt mosquito behaviour and that may have complex effects on survival [51,52]. For example, interventions that permit significant mosquito survival or that prevent mosquitoes taking full blood meals may increase the proportion of potentially infectious mosquitoes in the population or encourage multiple, partial blood feeds [20,53,54].…”

To Kill or to Repel Mosquitoes? Exploring Two Strategies for Protecting Humans and Reducing Vector-Borne Disease Risks by Using Pyrethroids as Spatial Repellents

“…Thus, at present, more large-scale studies are needed to clarify whether SRs can reduce VBDs [ 51 ]. Because conducting such studies is challenging, groups like Ten Bosch et al (2020) are developing models in which small-scale experimental data can be exploited to predict the epidemiological impacts of SRs at broader scales [ 54 ].…”