The effectiveness of putative wearable repellent technologies to protect against mosquito biting and Aedes-borne diseases, and their economic impact

by Robert T. Jones, Scott J. Tytheridge, Carolin Vegvari, Hannah R. Meredith, Elizabeth A. Pretorius, Thomas H. Ant, James G. Logan

Viruses transmitted by mosquitoes threaten the health of millions of people worldwide. There is an urgent need for new tools for personal protection to ensure that vulnerable individuals are protected from infectious bites when outdoors. Here, we test the efficacy of wash-in and spray-on repellents against Aedes aegypti. When applied as a treatment on clothing as well as skin, the novel repellent compound delta-undecalactone provided up to 100% protection initially, and over 50% bite prevention for more than 7 hours. Mathematical modelling indicated that if such a repellent, with 100% initial efficacy, were to be applied twice daily by 80% of the population, more than 30% of Zika virus infections could be averted in an outbreak scenario with a basic reproduction number R₀ = 2.2. In a less severe outbreak (R₀ = 1.6), the same repellent regimen could avert 96% of infections. If there was much lower uptake, with only 40% of people using the repellent twice per day, just 4% of Zika cases would be averted (outbreak R₀ = 2.2). Similar results were found in other scenarios tested for dengue and chikungunya outbreaks. Our model can be extrapolated to other repellents and guide future product development, and provides support to the concept that effective repellents that are used regularly and appropriately could be cost-effective interventions to prevent ill health from arboviral diseases.