Important advance! Study uncovers new drug potential in malaria fight

For years insecticide-treated mosquito nets have helped drastically reduce malaria infections, but insecticide resistance has led to the search for alternatives and a new study may have revealed an option. The weapon is familiar: a malaria drug already used by humans to prevent it from contracting the disease, and researchers now plan to use it in nets as insecticides.

His research shows that the drug works with mosquitoes, killing the malaria parasite on insects and preventing it from being transmitted. It is a potentially important breakthrough in the battle against a disease that killed 435,000 people in 2017, most of them children under five in Africa.

By 2017, the number of malaria cases has risen to 219 million, a worrying increase over the previous year and a sign that long-standing progress has been reversed. Researchers, including Flaminia Catteruccia, a professor of immunology and infectious diseases at Harvard University, found that exposing mosquitoes to low doses of an antimalarial drug called atovaquone or ATQ caused "complete parasite paresis."

"We tested a couple of anti-malaria drugs and it worked wonderfully with ATQ: all the parasites were killed!" Catteruccia told AFP by email.

Attacking inside mosquitoes

Initially, the team was looking for ways to sterilize female mosquitoes that had developed resistance to insecticides to prevent the spread of resistance. But when they found that the compounds they were testing also affected the malaria parasites inside the mosquitoes, they shifted the focus.

"We then think if we can attack parasites with nonspecific chemicals, why do not we try to kill them more effectively with antimalarials," Catteruccia said.

They settled in ATQ because, like insecticides, they can penetrate the "skin" of mosquitoes when they land on the nets. The team, whose research was published on Thursday in the journal Nature, tried to simulate the conditions in which insects land on the nets.

They fed two groups of mosquitoes with blood infected with malaria and then exposed one group to surfaces coated with ATQ. Just six minutes of contact with the surface – by the time insects used to pass a net trying to take a bite – eliminated the malaria parasites in the mosquitoes.

Control group mosquitoes that were not exposed to ATQ, however, "showed a high prevalence and intensity of infection (malaria)," the study said. The drug even worked to prevent mosquitoes from contracting malaria parasites when the insects came in contact with the drug 24 hours before ingesting infected blood.

The researchers said that computer modeling showed that their new approach would "substantially mitigate the overall effects of insecticide resistance on health" in the fight against malaria.

Substantial Obstacles

"We are very excited that this new idea can really help in the fight against malaria in a way that is safe for people who sleep under those nets and for the environment," Catteruccia said.

But researchers recognize that significant work is needed before antimalarials can be used directly against mosquitoes, and there are risks.

Mosquitoes are unlikely to develop resistance to ATC because this does not affect their survival or reproduction, but when it comes to malaria parasites, "the emergence of resistance is always a risk," Catteruccia said.

The perspective of an ATQ-resistant malaria strain is particularly problematic because the drug is a key piece in treating the disease in humans. To solve this problem, the researchers propose to investigate other drugs that kill the malaria parasite in different ways.

"By using different drugs in humans and mosquitoes, we could reduce the chance of drug resistance," Catteruccia said.

The team will also need to analyze the cost of using the drug and how stable it would be over time when exposed to the elements of a network. And the path to international acceptance will be long, wrote Janet Hemingway, a professor of vector biology at the Liverpool School of Tropical Medicine.

"Substantial obstacles must be overcome before a product that is recommended and universally accepted by funders, countries and communities for use in control programs is generated," she wrote in a review of the research commissioned by Nature.

There are also other factors at play in the growing number of malaria infections, experts say, including a decline in funding for campaigns against infection and a related drop in the use of insecticide-treated nets.