A drug used to treat a rare inherited disease has been found to make human blood toxic to malaria-carrying mosquitoes. It could provide another tool to reduce deadly insect populations.
Mosquitoes are considered the deadliest animal on the planet—carrying diseases that kill more than one million people a year. Scientists have found that a drug called nitisinone, which is used to treat people with a rare inherited disease called tyrosinemia, makes human blood toxic to mosquitoes.
Although it does not prevent the transmission of the malaria parasite Plasmodium, nitisinone is now being considered for further field tests as a chemical control to reduce the number of insects capable of spreading the disease.
What is the mosquito-killing drug?
Nitisinone is used to treat hereditary tyrosinemia type 1, which is a disease where people have too much tyrosine in their blood.
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Lab tests found that when a mosquito bites someone who has been taking nitisinone, the presence of the drug prevents the insect from being able to digest the human “blood meal” — 24 hours later, the insect dies. Nitisinone is toxic to mosquitoes in a way that it is not to humans.
Compared with ivermectin, another chemical that has been investigated as a mosquito vector control, nitisinone lasts longer in the bloodstream. It is also versatile, as it can be vaporised and sprayed on surfaces, meaning it can act like an insecticide.
An insecticide in your blood?
While field tests are required to ensure the drug is effective in malaria-prone areas, the early findings suggest it could be promising as a cheap and effective agent to control mosquito numbers. Importantly, it appears effective against mosquito species that have developed resistance to other control chemicals.
“It kills insecticide-resistant mosquitoes. There are a few insecticides that have been used in the field for decades [but] there are resistant [mosquito] lines in the community,” said Alvaro Acosta-Serrano, the joint supervisor of the study, based at Notre Dame University, US. “We tested those resistant lines with nitisinone and they are almost as equally susceptible as the susceptible lines of mosquitoes. It brings a lot of benefits, not only to mention that it performs better than ivermectin.”
“Recent reports have suggested the Trump administration may cut funding for health initiatives like malaria as part of a broader culling of programs supported by USAID.”
Anna Last, an associate professor in infectious diseases at the London School of Hygiene and Tropical Medicine, who was not involved in the study, said the findings were promising, particularly given results from recent field tests of ivermectin in vulnerable communities in Africa. “It’s a very relevant piece of work, I think, and does follow on from the slightly disappointing results from the majority of field trials looking at ivermectin, which showed that it didn’t perform in the way that we had anticipated and hoped, in the field,” Last told DW.
What methods are there to reduce mosquito-borne diseases?
The most recent World Health Organization data estimated that 263 million people were infected with the malaria parasite in 2023, resulting in 597,000 deaths. But there are several medical and technological tools for fighting mosquito-borne diseases like malaria.
Medical and social interventions are believed to have prevented 2.2 billion cases and 12.7 million deaths since 2000. The RTS,S vaccine, marketed as Mosquirix, for example, is 30 per cent effective at preventing severe cases and requires four doses. Other vaccines are also in development.
Mosquito nets treated with insecticides are also important tools. They are widely distributed across communities by various NGOs and health bodies.
Like the vaccine, nets are about “30 per cent effective”, according to Estrella Lasry, a senior malaria adviser at the Global Fund to fight AIDS, Tuberculosis and Malaria. “We try to cover as high a number as possible of the [malaria vulnerable] populations,” Lasry said.
But as well as insecticide use on nets and in the environment, insect control remains an important measure for groups trying to control the disease. This includes larval control—killing off mosquito hatchlings before they mature.
Can malaria be eradicated?
Malaria has already been eliminated from several countries in Latin America, Africa, and Asia. However, there is a risk that measures to contain the virus where it persists may stall if groups are unable to deliver services.
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Recent reports have suggested the Trump administration may cut funding for health initiatives like malaria as part of a broader culling of programs supported by the US Agency for International Development (USAID). There are also concerns of wider US cuts to medical research at home and abroad.
“It’s a really important issue at the moment. I think it will be devastating for health systems and programs, certainly across sub-Saharan Africa,” Last said. “But it will likely be wider reaching than that, I think, in the context of development of new molecules such as nitisinone. There will have to be a lot of focus on maintaining and sustaining existing excellent tools that we have that have really made huge gains in the last decade or more.”
