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Scientists have figured out how to spread a genetic self-destruct switch through a dangerous species - mosquitoes that carry malaria. NPR's Rob Stein reports that the advance is raising hopes and fears.
ROB STEIN, BYLINE: Malaria is one of the world's greatest afflictions. And despite decades of fighting the mosquito-borne disease, Andrea Crisanti at Imperial College London says malaria remains a major killer.
ANDREA CRISANTI: It still ranks amongst the most frequent diseases in the world. Malaria affects about 200 million every year and kills about 400,000, mainly children below the age of 5.
STEIN: So Crisanti's team decided to try something that's never been done before - use a powerful new kind of genetic engineering to modify a mosquito to destroy its own species.
CRISANTI: Our idea is to develop a genetic modification that is able to spread generation after generation to the point that all mosquito becomes genetically modified.
STEIN: And all the female mosquitoes become mutants. They can't bite or spread malaria and, more importantly, can't lay eggs. So eventually the population dies out.
CRISANTI: We go after the mosquito because it's the mosquito that transmit malaria - no mosquito, no malaria. It's a very simple equation.
STEIN: Crisanti's team released male mosquitoes carrying this self-destruct gene into cages filled with unmodified mosquitoes. They did it in a high-security basement lab in London to make sure none of the modified mosquitoes escaped. And it worked. The self-destruct mutation spread like crazy and quickly devastated the normal mosquitoes.
CRISANTI: Their entire population is wiped out, and they're completely eliminated.
STEIN: Crisanti says this shows these modified mosquitoes could be a powerful weapon against malaria and other insect-borne diseases.
CRISANTI: We're very excited. This is the first time that using a genetic construct, you can eliminate a dangerous species. This is a real game-changer.
STEIN: Other experts agree.
KEVIN ESVELT: This is an extraordinary paper.
STEIN: That's Kevin Esvelt, an evolutionary engineer at MIT.
ESVELT: We know what the costs of malaria are, and they are horrific. If we want to get rid of it entirely, we need some kind of breakthrough. This is a key step. This could save a lot of lives.
STEIN: But the idea of letting insects genetically modified like this loose in the world is raising big fears, including among some activists in Africa where the mosquitoes would be released first. Nnimmo Bassey heads the Health of Mother Earth Foundation in Nigeria.
NNIMMO BASSEY: It would be that Africa has become a testing ground for a technology that has not been proven, a technology that no one can say is safe definitively. We have a problem with this.
STEIN: The biggest fear is that wiping out a species of mosquitoes could wreak havoc with the environment. Ricarda Steinbrecher is a scientist with the group EcoNexus.
RICARDA STEINBRECHER: It could lead to ecosystem crashes. It could lead to other species coming in which are even more of a problem. It could have consequences on the whole food chain. It's beyond our ability to predict what the consequences are except that it could be really devastating and problematic.
STEIN: Crisanti and others dismiss fears that eliminating one species of mosquito would be a problem when there would still be hundreds of other mosquito species.
CRISANTI: We have eliminated viruses like smallpox. We are trying to eliminate polio. I don't see the big difference. I regard a mosquito that transmits malaria as a pathogen. And I think as a pathogen, we have the right to eliminate.
STEIN: But Crisanti and other scientists acknowledge more research is needed to prove the technology works and is safe, and a political and social consensus is needed before any organisms genetically engineered this way are ever released into the world. Rob Stein, NPR News.
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