A powerful new defence against malaria mosquitos
Imergard™ WP (wettable powder) is a perlite-based indoor and outdoor residual spray designed to provide a physical mode of action against mosquitoes capable of harbouring or transmitting human disease.
In their 2019 annual report, the World Health Organization reported 405,000 deaths from malaria, 67% of which were children under the age of 5 years old. Indoor residual sprays (IRS) have been an effective strategy to control malaria transmission and have helped reduce deaths in recent years. However, the overuse of traditional IRS pesticides has pushed natural selection towards resistance. Fewer people at risk of malaria are being protected by the IRS, declining from a peak of 5% coverage in 2010 to 2% in 2018, primarily as a result of insecticide resistance and rising costs of new technologies.
A new mode of action IRS with 11 months’ residual efficacy
Imergard WP can be applied to interior walls using standard backpack spray equipment. When the mosquito lands on a treated surface, there is a static transfer of Imergard WP particles, which absorb the lipid layer necessary for the mosquito’s survival.
In a community trial of 4,000 homes, completed in 2020 in Tanzania, Imergard WP was able to control the malaria parasite as effectively as the gold standard positive control, a micro-encapsulated Pirimiphos-methyl IRS.
At the conclusion of the study, Imergard WP maintained 100% efficacy after 72 hours against a threshold target of 80% mortality on all substrates for 11 months. An IRS that has 11 months of residual efficacy means it can be applied at any time of the year and not just during mosquito season, potentially driving an increase in IRS coverage.
High user acceptance and new potential treatment areas
There was a high level of user acceptance in the community trial involving 15 villages and 13,540 men, women and children. No serious adverse events were reported among sprayers or residents.
Imergard WP, like other IRS technologies, does not stop mosquitoes from blood-feeding; this is where insecticide-treated bednets (ITNs) have proven an invaluable tool with 50% of the population at risk being protected in 2018. However, in 2018 nearly 40% of pregnant women and children under five years of age, the most vulnerable population, did not sleep under an ITN.