For decades, insecticide-treated mosquito nets have been one of the most effective tools in the fight against malaria. But as mosquitoes develop resistance to commonly used insecticides, these technologies must evolve too. Interceptor G2, featured in TEL’s Solutions Toolbox, was developed to meet this challenge. In this article, the Gates Foundation explores the story behind the technology, how it works, and what it could mean for the future of malaria prevention.
From a lab in North Carolina, entomologist James Austin helped develop a new kind of mosquito net to protect families around the world from malaria.
Malaria is one of humanity’s oldest diseases—and one of the deadliest. It kills more than 600,000 people a year, most of them children in Africa under age 5.
Caused by Plasmodium parasites, malaria spreads from person to person through the bites of infected Anopheles mosquitoes, with the heaviest burden falling on young children in sub-Saharan Africa.
Malaria is also preventable and curable. Since 2000, insecticide-treated bed nets have helped prevent over 1 billion cases of malaria in Africa. For families in malaria-endemic communities, a bed net can provide protection and peace of mind while sleeping at night.
But mosquitoes are changing. They’ve been developing resistance to the insecticides traditionally used in bed nets, threatening decades of progress against mosquito-borne diseases. To protect hard-won progress, the world needs new tools to stay ahead of this ancient enemy.
That’s where James Austin comes in. Austin is an American scientist whose team helped create the Interceptor® G2 (IG2), a new kind of mosquito net designed to combat insecticide-resistant mosquitoes and better protect people from malaria.
Meet James Austin
Every morning at his home in North Carolina, Austin enjoys a cup of coffee, the Wall Street Journal, and quality time with Oliver, his 11-year-old goldendoodle. If it’s a nice day, he might sit by the pool and encourage dragonflies to land on his finger. He has loved the outdoors since his childhood in Texas, when he first developed a fascination with bugs.
It’s a serene beginning to a long day that Austin will spend studying—and fighting—the world’s deadliest creatures. As he says, “I’m interested in insects that give us trouble.” For his entire career—in pest control, as a research professor at Texas A&M University, and now as an entomologist in BASF’s Public Health division—Austin has parried with troublesome creatures like termites and Guinea worms. But none have proven more difficult than mosquitoes.
Why mosquitoes have become harder to stop
When Austin arrives at BASF’s offices in North Carolina’s Research Triangle, he usually starts his workday by answering e-mails. Most of his colleagues live and work in Europe, six hours ahead, so he has some catching up to do. But on some days, he goes to BASF’s nearby insect lab to test out a new hypothesis.
When malaria experts sounded the alarm about rising insecticide resistance, Austin and his BASF colleagues were among several private-sector research teams that began working on potential alternatives. “The problem,” he says, “is that the physical chemistry of some insecticides…requires some pretty demanding elements.” For one, they must be water-resistant, so they’ll stay on the net when it is washed. The chemicals must also do two things simultaneously: be deadly to mosquitoes and be safe for kids.
Austin had an idea. Earlier in his career, he helped to develop a pesticide called chlorfenapyr to combat termites. Instead of quickly killing bugs outright like many traditional insecticides, chlorfenapyr kills them slowly, exploiting their metabolism by depleting their energy until they die.
The Interceptor G2: A new way to fight malaria
Working with the Innovative Vector Control Consortium (IVCC), a global health partnership established in 2005 with support from the Gates Foundation, Austin’s team at BASF began developing the IG2, a new net that would include both traditional insecticide and the new chlorfenapyr solution. These efforts gained steam in 2018 with the launch of the New Nets Project, a push by the Global Fund to Fight AIDS, the Gates Foundation, and others to support the development and distribution of nets that could combat rising insecticide resistance.
While Austin had confidence that the new net would work, its development hit a snag when it came time to test the IG2’s effectiveness. Traditional pesticide testing involves putting mosquitoes in a small, enclosed space, such as a cone, and then coming back in an hour to see how many are dead. But chlorfenapyr takes longer to work. “You just aren’t able to capture the real value of this chemistry with those methods,” he says.
Fortunately, the IG2 showed its true worth in Phase II testing, which involved larger, open spaces and wild, free-flying mosquitoes. “There you could achieve the kind of mortality that is more representative of the chemistry,” Austin says. For example, a two-year randomized trial in Tanzania found that IG2 nets reduced malaria incidence by 45% among kids under age 10 compared with traditional nets.
How does the IG2 net work?
All insecticide-treated bed nets act as a physical barrier while also killing mosquitoes that land on the net.
Traditional bed nets use a single type of insecticide, pyrethroids, that kills mosquitoes by attacking their nervous system. In many places, mosquitoes have developed resistance to pyrethroids—meaning they don’t work as well as they used to.
The Interceptor G2 net adds chlorfenapyr, which interferes with the mosquitoes’ ability to produce energy. The combination of two insecticides with different modes of action has been the key control aspect.
Put simply, the IG2 uses a double line of attack to target mosquitoes through two mechanisms, with the goal of improving protection against malaria.
Protecting families one net at a time
At the end of his workday, Austin heads home to his wife and Oliver, and he often reads a history book or catches up on the latest scientific research.
In the case of chlorfenapyr, the latest research is exciting. Studies by Austin’s team suggest that IG2 nets aren’t just better at killing mosquitoes, they also attack the parasites within the mosquito that cause the malaria. “We have demonstrated that chlorfenapyr acts as an exogenous vaccine in some ways,” says Austin, “because it’s capable of killing both the vector and the parasite.”
With the New Nets Project, BASF distributed 35 million IG2 nets to eight African countries by the end of 2022; by 2026, the number had reached 61 million nets. “That’s one of the great things about working in public health,” says Austin. “Competency through chemistry translates to healthier lives for everyone. That’s why BASF invests consistently in research. Because innovation leads to saving lives.”
Living with mosquitoes, ending malaria
When he’s not spending his time fighting mosquitoes, Austin mentors other entomologists and strongly encourages young people to consider a career in bugs. Because after all, bugs are an essential part of our world.
“We share this world with insects,” he says. “Most of them were here long before we were. A lot of food webs rely on consuming mosquitoes, so targeted, focused, thoughtful approaches to living with insects are the way forward. We can live with mosquitoes, but we shouldn’t live with this disease.”
Republished by Technology Exchange Lab with permission from the Gates Foundation.
Learn more about Interceptor G2 in TEL’s Solutions Toolbox.
