Should we use a genetic weapon against mosquitoes carrying malaria?

T. H. Saey,  ScienceNewsExplores,  2022.

In a large laboratory cage, a male mosquito carries a genetic weapon that could launch the destruction of his species. That loss could also mean the end of the parasite that causes malaria. The weapon? A self-replicating bit of DNA known as a gene drive. It’s one of the most anticipated tools being developed to stop mosquitoes from spreading diseases like malaria to humans. It’s also one of the most controversial. The gene drive interferes with the insects’ ability to reproduce. In one small lab study, it wiped out captive populations of mosquitoes in just eight to 12 generations. A larger study in outdoor cages in Terni, Italy, worked too. Within as little as five to 10 years, this gene drive could be ready to test in the wild. Researchers are eyeing Africa for the first test release. There, malaria takes a huge toll. In 2020, it sickened close to 241 million people on the continent. And most of the globe’s 670,000 malaria deaths that year were in Africa. About eight in every 10 were children, the World Health Organization says. Many tools have been made to fight the disease. There are preventive drugs, insecticide-treated bed nets and even vaccines. These efforts are helping. But mosquitoes are developing resistance to insecticides. And some anti-malaria drugs may no longer work well. “To go toward zero [cases], we need to have something that is transformational,” says Fredros Okumu. By that, he means a completely new type of strategy. Okumu is a mosquito biologist. He directs science programs at Ifakara Health Institute in Tanzania, a country in East Africa. Gene drives might be the big change people are looking for. This technology was first devised in 2015. Researchers are still refining and testing it. Other types of genetically altered mosquitoes have been released in Brazil, the United States and elsewhere. But so far, those altered genes spread slowly among wild populations. Gene drives could potentially spread to nearly every member of a species quickly. In this way, they could forever alter the species. Or even wipe it out.

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