As a first step, the National Biosafety Agency in Burkina Faso gave Target Malaria, working with Diabaté, approval for a limited release of a male sterile mosquito strain (not a gene drive). In July 2019, 10,000 fluorescently coated, genetically modified mosquitoes were released in the village of Bana. It was almost literally a drop in the bucket compared to the wild population, but a hugely significant step nonetheless.
But the move has encountered fierce resistance from some Burkinabes. “We refuse to be guinea pigs,” says Ali Tapsoba, an anti-GMO campaigner, who fears the irreversibility of a gene drive and his country’s lack of resources to deal with it.37 Mariam Mayet, executive director of the African Centre for Biodiversity, calls Target Malaria a “neocolonial project designed and conceived in the West and telling us what’s good for us.”38 It is a common charge from African activists who have campaigned vociferously against the intrusion of giant agbiotech enterprises, notably Monsanto.
“Mosquitoes don’t obey national boundaries,” says Nnimmo Bassey, a vocal Nigerian environmentalist and critic of the mosquito program in Burkina Faso. Bassey is all for eliminating malaria, but he fears the possibility of CRISPR technology being used for other purposes. “Powerful countries and corporations don’t care about people who aren’t similar to them,” he says. “If you have this power and control in the world when there’s no equity, this seemingly nice scientific invention can become extremely dangerous.” Bassey favors more mundane low-tech solutions—sanitation, social services.
Of course there are risks associated with releasing gene-edited mosquitoes. Feng Zhang believes that any efforts to unleash gene drives into the wild must include containment measures.VI “Some days I feel it would be great to have no mosquitoes at all,” he said, but we must be wary of the ecological consequences. “You’re removing such a large fraction of the biomass. We need to be careful.”39
But aren’t the dangers of not trying it even greater? “It strikes me as a fake argument to say that something is irreversible,” says Church. “There are tons of technologies that are irreversible. But genetics isn’t one of them.” If something doesn’t work properly, he says it can be fixed, as Esvelt and Church have demonstrated in yeast.40
Church’s Harvard colleague, Amit Choudhary, grew up in India dreaming of being the next Sachin Tendulkar, the Babe Ruth of cricket, not a CRISPR scientist. His family was poor and there was no escaping the mosquitoes, but Choudhary avoided malaria thanks to a Good Knight vaporizer put out in the evening that released insect-repelling pyrethrins.
A chemist by training, Choudhary dares to compare CRISPR to some other transformational discoveries in human history such as fire or the Internet. It comes down to precision control, he says. Humankind was able to control fire. Contrast that with the chaos erupting because of a lack of precision control over the Internet.41 Gaining control of CRISPR is essential. To that end, Choudhary’s group has identified drug-like compounds that can suppress Cas9’s ability to cut DNA before it can grasp the relevant sequence.42
Choudhary thinks that the vaporizers of his childhood could be repurposed to help regulate gene drives by releasing custom chemicals that would regulate the activity of gene drives. Who needs a helicopter to douse mosquitoes when there is a device that already exists in almost every Indian home?43 And this could work in Africa too—anywhere dinner is cooked.
At the end of 2018, the UN Convention on Biological Diversity reached a compromise on gene drives, rejecting a moratorium but calling for the informed consent of impacted countries and local communities before contemplating any release.44 Could a gene drive spread across borders or to other species? Yes, perhaps. But isn’t biological warfare against one of the greatest killers of humankind worth the small risk? As Esvelt puts it, “the known harm of malaria greatly outweighs every possible ecological side-effect that has been posited to date, even if all of them occurred at once.”45
Scientists like Burt, Crisanti, and Esvelt are trying to save the lives of thousands of people each year. Crisanti rejects the criticisms that it would be immoral to attempt to use a gene drive, saying: “What about the moral issue of doing nothing?”46
A few years ago, I was sunbathing with my family on a beach in Scituate on Boston’s south shore. As we were packing up, a woman approached me. “Hey, do you know what’s on your leg?” Sure, I replied. I was sporting a circular rash on my calf, presumably caused by a spider bite. Or so I thought. She shook her head and in a thick Boston accent said: “No. That’s a tick bite. You’ve got Lyme disease.”
“How do you know?” I responded disbelievingly.
“I’m an ER nurse, love,” she said.
A hasty trip to my GP confirmed the diagnosis, which cleared up with the appropriate antibiotic. I shouldn’t have been so skepticaclass="underline" Lyme disease is particularly common in Massachusetts, where I lived. Picking deer ticks off my brindle beagle-boxer was a daily ritual after hiking in the neighborhood woods.
Tick-borne diseases might not seem to be a public health menace comparable to malaria, but Esvelt makes a convincing case. “The West Coast has earthquakes. The South has hurricanes. The middle of the country has tornadoes. The natural disaster of the Northeast is Lyme disease.”47 Each year, some 300,000 Americans are diagnosed with Lyme disease, signaled by the telltale bullseye rash on their skin. If left untreated, the disease can be debilitating. The disease and other tick-borne diseases are particularly prevalent on the islands of Nantucket and Martha’s Vineyard off Cape Cod.
Nantucket is a popular summer retreat for New Englanders and celebrities—and a perfect ecosystem for Lyme disease. Take a large deer population that has few constraints—no wolves, not enough licensed shooting or random car collisions. Lots of deer means lots of ticks, easily evidenced if you simply drag a sheet through the brush. But the ticks’ main host is the white-footed mouse, the elusive reservoir of tick-borne disease.
Together with Joanna Buchthal, Esvelt launched the Mice Against Ticks project to engage with a local community to discuss the idea of using CRISPR responsibly to engineer environmental immunity into the mice.48 If you could release sufficient mice edited with a gene cassette that confers resistance to Lyme disease, this could disrupt the ecological transmission cycle. By encoding antibody genes in the mouse germline that are expressed in newborn mice, Esvelt’s team could confer an inherited resistance to disease. Releasing enough genetically vaccinated mice should spread resistance to the next generation and disrupt the tick life cycle.
But first, Esvelt has to win over the residents of Nantucket. He felt a profound ethical obligation to share his research ideas with island residents, insisting that the public must have the final say. To his credit, Esvelt has spoken at public meetings on Nantucket convened by the Boards of Health, and faced vocal apprehension about the release of any genetically modified organisms. The Nantucket steering committee has some well-qualified individuals on it, including Howard Dickler, the former head of the NIAID’s infectious disease branch, and John Goldman, editor of an immunology journal. But there are skeptics, too.49 The consensus was: interested but don’t use any foreign DNA in our engineered mice.