To reduce malaria, treat infected mosquitos say experts

IN the fight against malaria, global health workers have long relied on bed nets treated with insecticide to ward off disease-transmitting mosquitos. But with insecticide resistance rising, a new study suggests an alternative approach: Use drugs to cure the insects before they can infect anyone.

Malaria spreads when a mosquito infected with a parasite bites a human.

“The real killer is the parasite that is transmitted by those mosquitos,” said Flaminia Catteruccia, a professor at the Harvard T.H. Chan School of Public Health and a co-author of the research. “So by eliminating the parasite, we eliminate the source of malaria.”

The scientists, whose work was published in the peer-reviewed journal Nature on Wednesday, identified roughly two dozen drugs they said can kill parasites within infected mosquitos. The treatments would be administered when the insects land on bed nets treated with the compounds.

Malaria remains a global scourge, ranking as the number four killer in low-income countries. And while deaths have declined in recent years, estimated cases have been rising, a 2024 World Health Organization report found. Warmer temperatures and flooding caused by climate change allow mosquitos to emerge and reproduce more easily. At the same time, global warming is opening up more environments for the infectious disease to spread, with mosquitos establishing themselves in new areas.

David Fidock, a professor at Columbia University Irving Medical Center who wasn’t involved in the study, called the research groundbreaking. This has “enormous potential public-health impact in reversing this trend that we’ve seen in recent years of malaria rates going up,” he said.

To continue the work and further develop drug candidates, though, the researchers said they will have to come up with new funding sources. The project has been affected by a National Institutes of Health funding freeze at institutions such as Harvard University. The NIH didn’t immediately return a request for comment.

---

How do the drugs work?

The researchers tested 81 antiparasitics, finding that 22 worked well against a key, malaria-causing parasite known as Plasmodium falciparum. Most of the 22 aren’t currently sold as treatments, though some are being tested for use in humans. The team also came up with two new compounds they hope to develop into drugs.

The two promising compounds are known as endochin-like quinolones and could be used together to target the parasites’ mitochondrial activity, key to replication and energy production. The drugs are straightforward and relatively cheap to manufacture and bed nets with them should cost less than $1 to $2 a piece, the researchers said.

As part of the testing process, the scientists applied the drugs to mosquito net-like materials in the lab and gauged their efficacy for over a year. Even material with only low doses of the compounds blocked parasites completely, said Alexandra Probst, a doctoral student and the study’s lead author.

The researchers avoided testing any medications currently used to treat humans because of concerns about fostering drug resistance. While resistance emerging in the parasites is a possibility, they said it’s unlikely because of how the drugs were designed and how the parasite functions within the mosquito.

A new approach

The researchers came up with the concept a few years ago by merging two common strategies used to fight malaria.

“No one had ever tried to kill parasites in the mosquito using drugs,” Catteruccia said. “Historically, the two sorts of worlds are very separate. People working on mosquitos try to kill them with insecticides and people working on parasites try to kill them with drugs.”

An earlier study utilized the antimalarial atovaquone in a similar way. But atovaquone is expensive and used to prevent and treat malaria in humans, so the scientists broadened their scope. Their approach could be implemented in as little as three to four years once its safety is further assessed, according to Columbia’s Fidock.

The scientists are working to test the new approach in Ethiopia and Burkina Faso, two countries in Africa where malaria is prevalent. They envision the compounds being used alongside insecticide, acting on insecticide-resistant mosquitos to prevent infections and malaria transmission.

The team said it’s in the process of seeking alternative funding sources to continue the research and further develop the two promising drug candidates.