A study published in Nature Communications describes a new way of controlling malaria using a microbial symbiont. A microbial organism that lives in mosquitos blocks the transmission of the malarial parasite from one human to the next.
Those mosquitos that carry the microbe known as Microsporidia MB do not also carry the malaria parasites (called Plasmodium falciparum). This appears to be the case both naturally in the wild as well as when mosquitoes are infected experimentally in the lab. Furthermore, Microsporidia MB is passed from a female mosquito to her offspring at high rates, and the symbiotic microbe does not seem to cause any harm to the mosquito host.
Malarial microbial symbiont
This is exciting research as it would point to an obvious method of naturally controlling the spread of infection without the need for anti-malarial drugs. Although the new Microsporidia MB symbiont is naturally found at relatively low levels in populations of malaria mosquitoes in Kenya, the researchers believe that there may be ways to increase the proportion of mosquitoes that carry the microbial symbiont.
Critical role of microbial symbionts
Malaria kills around 400,000 people each year and imposes a huge burden on Africa. The World Health Organisation (WHO) recently stressed the need to continue the efforts against malaria, despite the necessary focus on COVID-19, and said deaths from malaria could rise significantly across sub-Saharan Africa this year if work to prevent the disease is disrupted by COVID-19.
This study was led by researchers at the International Centre of Insect Physiology and Ecology (icipe) in Kenya and the University of Glasgow. Dr Jeremy Herren, icipe research scientist, who led the study said: “The bodies of animals are inhabited by microbes which are either detrimental or have neutral or beneficial symbionts. Healthy insects often have microbial symbionts inside their bodies and cells. These symbionts can have major effects on the biology of their hosts, and our team is trying to learn more about this type of microbe in insects that are important to human health.”
Microsporidia MB for malaria control
Prof Steven Sinkins, from the MRC-University of Glasgow Centre for Virus Research, said: “We are already 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”.
Dr Herren added: “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. 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.”