The Spatial Repellent Paradigm
A Quick Overview
Spatial repellents represent a new paradigm for vector control as they are designed to cause movement away from a location where humans are, cause attration inhibition and/or inhibit feeding on people. The goal of any of these responses is a reduction of mosquito-human contact to reduce pathogen transfer and resulting disease. This is different than traditional chemical uses which is intended to kill mosquitoes.
Spatial repellents may be offered as stand-alone tools where no other interventions are implemented, or most likely, combined with existing interventions to enhance efficacy of other mosquito control strategies. When used with other interventions, repellents may manage the spread of insecticide resistance and intervene in areas of the mosquito’s life cycle where other products do not reach.
Currently, there are 15 chemicals recommended by the World Health Organization for adult mosquito control representing only four chemical classes. The global community continues to place expectations of population-level protection using these very same, limited groups of actives in the same way on walls of houses and bed nets as that of the last 20years. Although this limited number of chemicals and application methods has contributed to decreasing malaria and dengue burden, they are becoming inadequate to sustain reductions in disease burden in many endemic countries. This is due, in part, to an overreliance on pyrethroids (which dominate the WHO shortlist of approved AIs) in both public health and agriculture and a resultant increasing occurrence of insecticide resistance, coupled with variable and poorly understood ecologies of different vector species.
The development of new products, and delivery strategies is needed. Although current global adult mosquito control strategies such as insecticide-treated bed nets, indoor residual spraying for malaria and space-spraying for dengue can be effective under certain circumstances these are limited in combating the transmission of pathogens in all areas where the diseases occur. Interventions must be adaptable according to the behavior of the mosquitoes that are being targeted (biting inside or outside the houses, at daytime or at night).
Data from the current program is intended to be used by global, regional and local public health authorities for consideration in the development of a recommendation that spatial repellents be included in disease control programs, thereby improving the quality of life in at-risk human populations.