Research is a step closer to eradicating malaria
Malaria is a disease most commonly contracted in the tropical and sub-tropical regions of our planet by the protozoan Plasmodium. There are several different species of Plasmodium that cause malaria in various forms and severity. The malaria parasite is transmitted by the female Anopheles mosquito which bites mostly between dusk and dawn.
Sub-Saharan Africa accounts for 93% of worldwide cases and 94% of the 400,000 worldwide deaths caused by malaria. It is in this region where in 2017 a team of Kenyan and UK scientists found a novel method with significant potential to completely stop mosquitoes from transmitting the malaria causing parasite.
The discovery of a possible break in the transmission chain
Healthy mosquitoes often have microbial symbionts that can alter the biology of their hosts. One of these symbionts, Microsporidia MB which was found in around 5% of studied mosquitos had the effect that the mosquito could not be infected with Plasmodium falciparum, one of the most common and deadly malaria parasites in Africa. This was found in laboratory conditions but also works in nature as the microbe-carrying mosquitoes are prevented from also carrying the malaria parasite.
This discovery could be a major factor in breaking the transmission chain. Thus far, most interventions have focussed on preventing humans from being infected through mosquito nets and chemoprophylaxis. Progress with insecticide treated mosquito nets has plateaued at an estimated 40% reduction so a different approach is necessary. Malaria presents a major burden on the economic development of sub-Saharan Africa therefore research into this debilitating disease is ongoing. The Kenyan-UK team says that these new findings have “enormous potential” to finally control the disease. One of the scientists, Jeremy Herren from the International Centre of Insect Physiology and Ecology in Kenya even spoke of data showing a “100% blockage” of malaria.
Microsporidia MB settles in the insect’s midgut and ovaries and is not known to affect the insect’s fertility or survival. In addition, the microbe can be passed on from female mosquitoes to eggs and offspring, making it even more ecologically sound.
More research is still needed
The beneficial microbe is closely related to fungi and lives as a symbiont with the Anopheles mosquito. One of the ideas is to release spores to suppress the disease, another to release spore infected insects into the wild. Further studies are still needed to find the best possible mechanism to control malaria transmission with these findings.
Similar research already exists in combating dengue fever. For this disease, the MRC University of Glasgow Centre for Virus Research reports “using a transmission-blocking symbiont called Wolbachia to control dengue, a virus transmitted by mosquitoes. The Microsporidia MB symbiont has some similar characteristics, making it an attractive prospect for developing comparable approaches for malaria control”.
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