None of humankind’s battles has proved more enduring—or less successful—than the war on mosquitoes.
Around the world each year, millions of people die of diseases spread by the insect. It’s a familiar list of stubborn plagues—malaria, West Nile, dengue, yellow fever, forms of encephalitis—with some chilling recent additions. The mosquito-borne chikungunya virus has spread to parts of Africa, Europe, Asia, and as of 2013, the Americas. Its effects, while painful, pale in comparison with those of the Zika virus, which is careering through the Western Hemisphere and leaving tragically damaged babies in its wake.
We have drained cesspools, warned of the dangers of standing water, and sprayed a river of pesticides. We have put up bed nets and window screens; we have educated and exhorted. And yet, by any fair measure, we’re losing this fight. The mosquito remains the most dangerous nonhuman animal on Earth—and many scientists fear it may become even more prevalent and virulent with the rise in global temperatures and international travel.
Our next weapon of choice is DNA. Scientists are working to neutralise the mosquito on its swampy home turf by altering its genetics. New gene-editing techniques, make it possible to tweak the mosquito’s genome so it can’t spread the malaria parasite. Another approach would genetically modify mosquitoes so that they bear sterile offspring. And yet another would alter mosquitoes’ genes to prevent the birth of females—the ones that bite—so the diseases will stop spreading and, in time, the insect will die out.
Some may see these techniques as a revolutionary advance against infectious disease; others, as an unnerving case of scientists playing God. Like many breakthroughs, this one raises profound ethical questions. No matter how noxious a wild species is, can we afford to risk the consequences of altering its genetic code? Or can we afford not to, as malaria alone kills, on average, one child every two minutes in Africa?
Header Image: During World War II the U.S. military used cartoons to tell troops how to protect themselves from malaria. PHOTOGRAPH BY FRANK MACK, FOR THE U.S. ARMY; COURTESY NATIONAL LIBRARY OF MEDICINE