Over 200 million people get sick from malaria every year, and more than 420,000 of them die, mostly children in sub-Saharan Africa. Scientists have been struggling to find new ways to kill mosquitoes because the mosquitoes that spread the parasite have become increasingly resistant to insecticides, thus making it extremely hard to control the disease.
The people that suffer the most casualties are the poor. Where there is the worst poverty is where you get the highest incidence of malaria. Luckily, for those less fortunate folk, there is hope. A new way to fight malaria has been developed by researchers from Burkina Faso and the University of Maryland. It involves fungus that has been genetically engineered with a spider gene to produce venom that can quickly kill mosquitoes.
They even took the testing out of the lab setting and into a 6,550 sq ft screened enclosure in Burkina Faso, West Africa, to understand if (and how) it would work in a real-world setting and how it would affect everything else in the environment. And it worked! Their genetically modified fungus wiped out the malaria-carrying mosquitoes in just a month and a half without harming any other living organism. This is the closest any scientists have come to studying the potential impact of releasing an engineered organism in the wild. “We’re very excited,” says Raymond St. Leger, a professor of entomology at the University of Maryland who led the research. “The results are very good. This could save many lives.”
The Study
They “supercharged” a naturally occurring parasite of the anopheles mosquitoes. (They chose the anopheles mosquito because it is a major carrier of the malaria parasite.) They genetically modified the fungus using a gene from the Blue Mountains funnel-web spider. “We put into the fungus this specific gene from a spider, which produces a toxin. But it only makes it when the fungus is swimming in insect blood,” St. Leger says.
To test the genetically modified fungus in something close to a natural setting, they erected a “MosquitoSphere”—a structure that resembles a large greenhouse, with walls made of mosquito netting. They wanted to mimic the locality, so within this space they erected six compartments, including four designed to resemble typical huts in the region. The interior was thoughtfully designed to simulate a village setting with local plants, the typical huts, small pools of water, and a food source (calves) for mosquitoes.
They put the fungi in sesame oil and spread it on black sheets all around the inside of the huts. (Mosquitoes are attracted to black objects. The intention was for the mosquitoes to pick up the fungi when they rest on the sheets after feeding on live calves.)
With everything prepared and in place, they released about 1,500 Anopheles coluzzi mosquitoes into each hut.
Then, they compared what happened to the mosquitoes inside the huts with the modified fungus compared with the mosquitoes inside huts with unmodified fungi or no fungi.
The Results
The modified fungus proved to be a highly effective mosquito killer.
Within a 45-day trial, over 99% of the populations of mosquitoes in the huts with the modified fungus crashed. “Within two generations, the mosquitoes were basically gone,” St. Leger says. “They’re finished.”
It also worked effectively in mosquitoes who were resistant to conventional insecticides.
Based on laboratory experiments, the fungus seems harmless to other insects, such as bees. “These fungi are very selective,” said St Leger. “They know where they are from chemical signals and the shapes of features on an insect’s body. The strain we are working with likes mosquitoes. When this fungus detects that it is on a mosquito, it penetrates the mosquito’s cuticle and enters the insect. It won’t go to that trouble for other insects, so it’s quite safe for beneficial species such as honeybees.”
The study has been published in the journal Science.
Supporters and Skeptics
The fact that they were even able to test a genetically modified organism in an outdoor setting is a big deal. Testing in the field has been curtailed by the significant ethical and environmental considerations of releasing an organism that could have an unknown impact on the ecosystem. “No transgenic malaria control has come this far down the road towards actual field testing,” said Brian Lovett, lead author of the study.
While some are impressed and praise the researchers’ advance, others are worried the approach may be unsafe. “Fighting malaria is something that everybody should do. But fighting malaria through genetic engineering is dangerous,” says Nnimmo Bassey of the Health of Mother Earth Foundation, an advocacy group based in Nigeria. “I’m heavily worried that Africans are the preferred guinea pigs for experimentation, and Africa is going to become a large laboratory for risky experimentation,” he added. “We don’t want this to happen.”
Another skeptic, Dana Perls of Friends of the Earth, an environmental group, echoing the objections of the Health of Mother Earth Foundation, said: “This study raises several urgent concerns. Genetic engineering of fungus could have problematic negative public health impacts and unpredictable ripple effects on ecosystems, affecting pollinators, bats, and bees. Like with all genetic engineering, this needs to be addressed with great caution.”
However, St. Leger stressed that much more research is needed to further evaluate the fungus before anyone considers releasing the organisms in the wild. “Nothing is going to happen without the acceptance of the local people who would be exposed to the fungus, its benefits, and any potential risks,” he says.
St. Leger believes the toxic fungus could provide a powerful new weapon to fight malaria. “From our scientific understanding, so far it’s safe,” he says. “If it just reduced the transmission of malaria by 5%, that would still be hundreds of thousands of lives that benefited. And we think it could do quite a bit better than that.” For a completely different chemical-free approach, China’s laser mosquito defense system uses LiDAR and a precision laser to disable mosquitoes in flight.
