By Fiona Broom *
A fungus found in mosquitos, which transmit malaria, could fuel global efforts to fight the disease, which kills around half a million people each year, mostly children under five.
Scientists have discovered a microbe, a fungus they have named Microsporidia MB, in Anopheles arabiensis mosquitoes on the shores of Lake Victoria in Kenya. The fungus can block the transmission of malaria from mosquitoes to humans.
Malaria prevention and control organizations are optimistic that the results could provide a permanent solution to malaria, a disease that infects approximately 220 million people annually.
The vast majority of cases of malaria occur in Africa and India and are caused by the P. falciparum parasite, which is transmitted by female Anopheles mosquitoes.
With regard to P. falciparum, researchers from icipe, the International Center for Insect Physiology and Ecology, and the University of Glasgow reported in a study published this week (May 4th) that mosquitoes with the fungus do not carry or chase malaria parasites in nature an experimental infection in the laboratory.
The fungus Microsporidia MB occurs naturally in small amounts in malaria mosquitoes in Kenya. However, the researchers believe that there are ways to increase the number of mosquitoes that carry it, thereby blocking their ability to transmit malaria. Only female mosquitoes bite people.
Further research will investigate exactly how Microsporidia MB can be used to combat malaria in large mosquito populations. However, the researchers argue that it is scalable and can be transported to remote areas via plane drops of air from mosquitoes or spores infected in the laboratory.
The microbe is passed on at high rates from female Anopheles arabiensis mosquitoes to their offspring and does not kill or harm the mosquito host or impair its fitness.
This means that using the fungus to fight malaria would leave mosquito populations intact, as opposed to techniques like genome editing that could wipe them out.
“Perhaps the first step is to look at what’s natural out there and see if it can work,” lead author Jeremy Herren of icipe and the former University of Glasgow told SciDev.Net.
Herren says his background of studying fruit fly and insect symbionts – organisms that live together – led to the study.
“I always thought that the concept of symbiosis could be really effective in controlling disease,” he said. “I got into vector-borne disease research from this perspective.”
The nonprofit Malaria Consortium is “excited” about the discovery of Microsporidia MB, but says more studies will be needed to confirm the results with larger samples of mosquitoes and other major mosquito species.
Timothy Wells, chief scientist at Medicines for Malaria Venture, says anything believed to have an impact on malaria transmission is “good news.”
“This discovery is extremely interesting and it will be fascinating to see how the technology can be developed to have an impact on clinical malaria,” he says.
James Tibenderana, global technical director of the Malaria Consortium, says any possible use of the results for malaria control will require more extensive field studies to demonstrate effectiveness, cost-effectiveness, and understand operational challenges.
“The acceptance of the approach among national governments and communities needs to be assessed,” says Tibenderana.
Herren agreed that demonstrating effectiveness and dealing with policy makers is key to public health interventions.
He says community acceptance is critical before environmental releases can be considered.
“We worked a lot with the communities, they were actually an important part of this research,” says Herren.
“They could be the first to benefit if it works. We have to make sure they understand what we are doing and of course it is up to them whether they want this intervention or not.”
However, ecologists remain aware of the potential impacts on the environment and public health.
Biologist Tom Wakeford of the ETC Group, a not-for-profit conservation and technology company, urges caution with the discovery.
“[Microsporidia MB] is a naturally occurring biological organism … but whenever you release something as a biological control agent, you don’t know what will happen. Ecologically, we don’t know what to do with pollinators or other organisms that are key elements of ecosystems. “
However, according to Herren, his research indicates that Microsporidia MB is unable to infect other organisms. “There is probably a risk in everything, but I think in that case it would be very small if you take something that is already there and increase the prevalence,” he says.
* About the author: Fiona Broom is the acting global editor of SciDev.Net
Source: This article was published by SciDev.net