Small bugs, big breakthroughs

What do humans and cows have in common? Among other things, we’re both victims of tiny insects.

For cows, the latest culprit is the New World screwworm. Despite the name, the screwworm is actually a type of fly that likes to lay its eggs on animals like cows, which creates an often-fatal wound on the animal’s hide. Screwworms once killed up to one million cattle a year here in the United States, and sixty years after we eliminated them in our country, they’re back.

For humans, one of our greatest nemesis is the mosquito. There are plenty of reasons to hate mosquitoes, but malaria is easily at the top of the list. The disease kills more than 600,000 people every year, most of them children, and it’s transmitted when a mosquito infected with a parasite called Plasmodium bites you.

Protecting people (or cattle) from an insect poses an interesting challenge. How do you stop something so small from hurting anyone? There are lots of different ways to approach the problem.

One approach is to keep insects out of the places where people are. There are already lots of tools that do this with mosquitoes, with more in the pipeline. The most widely used is the bed net, a gauzy sheet of fabric treated with an insecticide that kills any mosquito that tries to reach the person sleeping under it.

Bed nets are magical. In some places where malaria is endemic in Africa, they’ve reduced the number of children who die before the age of 5 by 20 percent. But there’s a problem: Mosquitoes can develop resistance to the insecticide used in bed nets, just like bacteria can evolve resistance to antibiotics.

Enter the dual active ingredient bed net. (You’ll often see them referred to as dual AI nets, even though they have nothing to do with artificial intelligence.) By treating bed nets with two different insecticides, scientists have been able to figure out how to negate a mosquito’s resistance and keep people safe. The catch is that dual AI nets are more expensive than regular bed nets, which is why the Global Fund and the Gates Foundation stepped in to make them affordable for the countries that needed them most. The results so far have exceeded my expectations. Dual AI nets now make up more than half of the bed nets used, just two years after they became available.

Bed nets have another flaw: They only protect you while you’re under them, even though mosquitoes are also active in the hours before you go to sleep and after you wake up. A new tool called a spatial emanator aims to bridge that gap. It basically works like a plug-in air freshener—but instead of releasing a nice fragrance, it slowly releases an insecticide at a low-enough dose that doesn’t harm people but drives away any mosquito that might enter your home.

When spatial emanators received the green light for use a year ago, they became the first new malaria-prevention tool the WHO has recommended in over a decade. I’m super excited about their ability to protect people from mosquitoes for more hours of the day.

Another approach to stopping insects is to target them at the population level. That’s how the world stopped screwworm the first time. In 1954, scientists figured out a way to use radiation to make the males sterile. They released the neutered insects into the target area, and since they couldn’t reproduce, the population died off. This approach worked sixty years ago, and it still works today (and scientists are working on even more effective methods).

What if we could use a similar approach to stop mosquitoes? Last year, I wrote about an incredible project in Tanzania called Transmission Zero. The idea behind it is simple: a mosquito that can’t give you malaria.

Tanzanian scientists have found a way to make Anopheles gambiae mosquitoes—the species responsible for most of the malaria in Africa—produce two types of molecules, naturally found in frogs and bees, that block the parasite from developing inside the insect. The mosquitoes would continue flying around, doing their mosquito business, but they wouldn’t be able to make anyone sick with malaria. Each time they mated with another mosquito, they would pass on the gene that protected them from the parasite. (I just published a new profile of Dr. Lina Finda from the Ifakara Health Institute in Tanzania, who is helping lead this work.)

These malaria-free mosquitoes could potentially help save tens of thousands of lives every year. And Tanzania isn’t the only country on the cutting edge of advancing this work. The Ugandan Virus Research Institute and the University of Sciences, Techniques and Technologies of Bamako in Mali are also doing pioneering work to move the field forward. Scientists are learning more every day about the role mosquitoes play in ecosystems, and research is now underway on two other species beyond Anopheles gambiae.

Dual AI bed nets, spatial emanators, and malaria-free mosquitoes are just the latest breakthroughs to come out of the robust malaria innovation pipeline. Treatments continue to get better, and vaccines are already proving to save lives, with even more effective next-gen vaccines to come. A lot of interesting work is underway with endectocides, a type of drug that could potentially make your blood toxic to mosquitoes. There’s even a fascinating trial that looks at whether targeting mosquito larvae in rice paddies could make a difference. The goal of this trial is to stop malaria, but early results from Nigeria and Rwanda indicate that larval control could boost rice yields as much as 50 percent, which would be incredible for farmers.

Unfortunately, while the R&D progress we’re making is remarkable, the same can’t be said for the fight against malaria overall. Donor governments are cutting health aid—including money for the Global Fund, which has saved more than 70 million lives to date by helping deliver lifesaving tools like bed nets. Last year, our partners across Africa pulled off a miracle to minimize the impact of the cuts. With support from our foundation, they found creative ways to distribute supplies that were already in warehouses across the continent.

This year, the picture looks different. While some funding has since been restored, cuts from multiple donor governments mean it's not yet enough to guarantee bed nets and other tools reach every family who needs them. Our foundation is doing everything we can to help close that gap. I continue to advocate for increased funding, because it is ridiculous to put the health of the world’s children at risk when we know how to save them.

I believe we can end malaria forever. We have some of the tools we need already, and I think we’ll have the rest soon. We can defeat mosquitoes, just like we stopped screwworm more than half a century ago and just like we’ll stop it again. The question is whether the world will choose to make it happen.

The choice is obvious to me. We have an opportunity to ensure that no child dies from malaria ever again. Let’s take it.