In 2018, the World Health Organisation estimated 228 million cases of the mosquito-borne disease, and 405,000 deaths.
But a new study may have found a brand new, highly effective way to stop the spread – and it was inside the mosquito all along.
The team discovered that a new type of spore-forming single-celled microbe found in mosquitoes, which they've called Microsporidia MB, has the amazing ability to stop the transmission of Plasmodium falciparum – the parasitic protozoan which causes most malaria cases.
It also doesn't seem to hurt the mosquito, meaning that if we can increase the prevalence of Microsporidia MB in local mosquito populations, it could be a good way to stop malaria in its tracks without having to mess up the rest of the ecosystem.
"As a microbe that impairs Plasmodium transmission that is non-virulent and vertically transmitted, Microsporidia MB could be investigated as a strategy to limit malaria transmission."
The idea that a mosquito microbe could be stopping the transmission of a disease isn't exactly new. Wolbachia, a genus of bacteria that naturally occurs in mosquito populations, has shown incredible potential for wiping out dengue and other mosquito-borne infections.
"We are already using a transmission-blocking symbiont called Wolbachia to control dengue, a virus transmitted by mosquitoes," University of Glasgow microbiologist Steven Sinkins says.
"The Microsporidia MB symbiont has some similar characteristics, making it an attractive prospect for developing comparable approaches for malaria control."
This research is currently in its early stages – but the team found that when they analysed mosquitoes taken from field studies in Kenya, those with Microsporidia MB did not have the malaria parasite. Even when they let the mosquitoes drink infected blood, the mosquitoes with Microsporidia MB had reduced levels of infection and no signs of the malaria parasite's spores were detected.
Because Microsporidia MB is passed down the maternal line, once it's in the mosquito population, it's unlikely to be going anywhere. The team found that some areas they tested already had nine percent of the mosquito population with the malaria-busting microbe.
The team hopes that with more research we can find out if it's possible to increase the amount of Microsporidia MB in the mosquito population – with the eventual goal of lowering rates of malaria.
"Further studies will be needed to determine precisely how Microsporidia MB could be used to control malaria. The next phase of the research will investigate Microsporidia MB dynamics in large mosquito populations in screen house 'semi-field' facilities," says International Centre of Insect Physiology and Ecology microbiologist, Jeremy Herren.
"The results of these studies will give us key information that will be used to determine how we could then disseminate Microsporidia MB for malaria control."
The research has been published in Nature Communications.