Malaria is transmitted through the bite of infected mosquitoes
Scientists have discovered a microbe that completely protects mosquitoes from becoming infected with malaria.
The team in Kenya and the UK says the finding has “enormous potential” to control the disease.
Malaria is transmitted by the bite of infected mosquitoes, so protecting these mosquitoes could in turn protect people.
The researchers are now investigating whether they can release infected mosquitoes into the wild or use spores to suppress the disease.
What is this microbe?
The malaria-blocking beetle Microsporidia MB was discovered through an investigation of mosquitoes on the shores of Lake Victoria in Kenya. It lives in the intestines and genitals of insects.
The researchers couldn’t find a single mosquito with the microsporidia that harbored the malaria parasite. And laboratory experiments published in Nature Communications confirmed that the microbe provided protection for the mosquitoes.
Microsporidia are, or at least closely related to, fungi, and most are parasites.
However, this new species can be beneficial to the mosquito and was naturally found in around 5% of the insects studied.
How big is the discovery?
“The data we have so far suggest that this is a 100% block, it is a very severe block of malaria,” said Dr. Jeremy Herren from the International Center for Insect Physiology and Ecology (icipe) in Kenya told the BBC.
He added, “It’s going to be quite a surprise. I think people are going to see this as a really big breakthrough.”
Malaria kills more than 400,000 people each year, most of them children under the age of five.
While tremendous advances have been made in the use of bed nets and the spraying of insecticides on homes, this has stalled in recent years. There is broad consensus that new tools to fight malaria are needed.
Bed nets have helped reduce the number of people infected with malaria around the world
How does the microbe stop malaria?
The fine details have yet to be worked out.
But Microsporidia MB could boost the mosquito’s immune system so it can fight off infection better.
Or the presence of the microbe in the insect could have a profound effect on the mosquito’s metabolism, rendering it inhospitable to the malaria parasite.
Microsporidial MB infections appear to be lifelong. If anything, the experiments show that they become more intense, so that the malaria-blocking effect is long-lasting.
When can this be used against malaria?
At least 40% of the mosquitoes in a region must be infected with microsporidia in order to significantly reduce malaria.
The microbe can be transmitted between adult mosquitoes and is also passed on from the female to her offspring.
Therefore, the researchers are investigating two main strategies for increasing the number of infected mosquitoes.
- Microsporidia form spores that can be released en masse to infect mosquitoes
- Male mosquitoes (who do not bite) could be infected in the laboratory and released into the wild to infect the females during sex
“It’s a new discovery. We are very excited about the malaria control potential. It has tremendous potential,” Prof. Steven Sinkins of the MRC Center for Virus Research at the University of Glasgow told the BBC.
This concept of disease control with microbes is not unprecedented. A type of bacteria called Wolbachia has been shown to make it difficult for mosquitoes to spread dengue fever in real-world studies.
- Bacterial allies make dengue fever cases pop up
- GM fungus quickly kills 99% of malaria mosquitoes
What happens next?
Scientists need to understand how the microbe spreads, so they plan to conduct further tests in Kenya.
However, these approaches are relatively undisputed, as the species is already found in wild mosquitoes and does not introduce anything new.
It would also not kill the mosquitoes and thus have no impact on ecosystems that depend on them for food. This is part of other strategies like a killer fungus that can cause mosquito populations to collapse almost entirely in weeks.
Follow James on Twitter