World Mosquito Day 2021 – 20th August 2021
Today is World Mosquito Day. On this day in 1897, Sir Ronald Ross discovered that Anopheles mosquitoes were responsible for the transmission of the malaria parasite. Ross’s discovery revolutionized our understanding of how to prevent malaria. Steps could be taken to target the mosquito vector to control the disease. One hundred and twenty-four years later, mosquito vector control remains a mainstay of malaria prevention. It has been estimated that between 2000 and 2015, 450 million clinical cases of malaria were averted by the widespread distribution of insecticide-treated bed nets.
Until 2019, all insecticide-treated bed nets distributed throughout Africa were treated with only one class of insecticide, pyrethroids, contributing to increasing levels of pyrethroid resistance in mosquito populations. Increases in pyrethroid resistance threaten the gains that have been made against malaria since higher levels of resistance may reduce the ability of pyrethroid-based bed nets to protect people from infectious mosquito bites.
The IVCC led New Nets Project (NNP), established in 2018 with co-funding from Unitaid and the Global Fund and complementary funding provided by the Bill & Melinda Gates Foundation and USAID, works with the next generation of nets, which are dual-insecticide nets, containing both a pyrethroid and a second insecticide. BASF’s Interceptor® G2 nets contain a pyrethroid and chlorfenapyr, and DCT’s Royal Guard® nets contain a pyrethroid plus pyriproxyfen. NNP was established with the goal of making the latest resistance-breaking net technology more widely available and affordable to malaria programmes throughout Africa by managing the pilot deployment of nets with reduced pricing via a co-payment mechanism and volume guarantee provided to BASF by MedAccess, while also establishing the evidence needed to support a policy decision by the World Health Organization (WHO) to recommend dual-insecticide nets over standard pyrethroid nets.
Although there is entomological data available showing increased mosquito mortality in hut studies for the Interceptor® G2 net and reduced mosquito fecundity for the Royal Guard® net compared to a standard pyrethroid net, two randomized control trials providing epidemiological data are required by the WHO prior to issuing a recommendation. We eagerly anticipate results from one such study in Tanzania (funded by Wellcome Trust) that will be available later this year, as well as results from a study in Benin as part of the New Nets Project that will be available in 2022. Both studies are being led by the London School of Hygiene and Tropical Medicine.
Over 20 million Interceptor® G2 and 1.5 million Royal Guard® nets have been distributed through NNP in 8 countries since 2019. By the end of the project in 2022, over 35 million Interceptor® G2 nets will have been distributed, data from the two randomized control trials will be available, and five observational studies will have collected entomological, anthropological, incidence, prevalence, net durability, and cost-effectiveness data to support impact modelling and country deployment decisions.
NNP will not only result in accelerated access to new nets but will also establish critical guidance to countries looking for the best value for money in controlling malaria. NNP is currently over one year ahead of schedule in reaching the Interceptor® G2 volume guarantee and associated price reductions. This has helped to lay the foundation for the Global Fund’s Net Transition Initiative that will help partner countries access additional new nets for the same price as standard pyrethroid nets and conduct additional research pending WHO’s review of the data and subsequent decision on their policy recommendation.
The development and deployment of dual-insecticide nets throughout Africa continue our fight against the mosquito vector of malaria first recognized by Sir Ronald Ross. Today, on World Mosquito Day, let us reflect on his seminal discovery and all the advances we have made since in combatting malaria, while also recommitting ourselves to eliminating this mosquito-borne disease.
