In 2023, malaria killed 497,000 people (World Health Organization Malaria Report, 2024). The malaria parasite was discovered in 1880, and Sir Ronald Ross in 1897 identified the role of mosquitoes as vectors in the transmission of malaria. Since Ross’s breakthrough, malaria management has heavily relied upon mosquito control. Bhatt et al (2015) demonstrated that in the African continent where 95% of the world’s malaria cases occur, approximately 68% of cases were prevented between 2000 and 2015 due to the use of insecticide impregnated nets. If indoor residual spraying is added, roughly 78% of all malaria cases were prevented over the same time frame (Bhatt et al, 2015). Vector control is an essential component of malaria prevention and management.
However, since 2015, the elimination of malaria worldwide has stalled with the evolution of insecticide resistance as a major factor (World Health Organization, 2024 World Malaria Report), 2023). Mosquito behaviour also poses a major problem. In the Asia Pacific region, vector control is extremely challenging due to multiple mosquito species preferring to bite outdoors and earlier in the day, resulting in many more cases of malaria. Bosco in Papua/New Guinea found that 80% malaria transmitting mosquito bites occurred outdoors with mosquito resting places unknown. (APMEN, 2025). The impact of insecticide impregnated bed nets and residual spraying would appear to have become severely limited in Papua/New Guinea. The need for effective outdoor management of mosquitoes is urgent but there are few resources.
The World Health Organization has recently recommended spatial emanators which examine the effects of passively dispensed chemicals on mosquitoes, including the disruption of host seeking, blood feeding, morbidity and mortality, and can adjust the dose as required (Swai & Moore, 2025). Spatial emanators can be effective for 12 months or more and are easy to install. The World Health Organization recently prequalified Mosquito Shield and Guardian both of which emit an effective ingredient named transfluthrin (World Health Organization, 2025). Spatial emanators are a much-needed addition to the mosquito management toolbox. World-wide ongoing studies are required to keep abreast of the effectiveness of bed nets, indoor residual spraying and the biting behaviour of malaria transmitting mosquitos so that optimal management is used. The challenge as always, is to distribute resources to where they are needed.
Spatial emanator being installed. Photo courtesy of David Amollo/UnitAid (2025).
References
APMEN 2025, Papua New Guinea Scientists Study Biting Behaviour of Malaria Mosquitoes. Located August 26th, 2025, at Papua New Guinea Scientists Study Biting Behaviour of Malaria Mosquitoes | APMEN
Bhatt et al, 2015 The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Located September 5th, 2025, at https://www.researchgate.net/publication/281837736_The_effect_of_malaria_control_on_Plasmodium_falciparum_in_Africa_between_2000_and_2015
Swai, J. K., & Moore, S. J., 2025, Beyond repellents: spatial emanators for the control of malaria in Africa. The Lancet, vol 405, issue 10473, pp. 101-103.
World Health Organization, 2024, World Malaria Report 2023. Located January 15th, 2025, at World malaria report 2024
World Health Organization, (August 13th, 2025), WHO recommends spatial emanators for malaria vector control and prequalifies first two products. Located September 7th, 2025, at https://www.who.int/news/item/13-08-2025-who-recommends-spatial-emanators-for-malaria-vector-control-and-prequalifies-first-two-products