Nitisinone: Malaria breakthrough as scientists find drug for rare disease makes human blood deadly to mosquitoes

A drug for a rare disease makes human blood deadly to mosquitoes and could help in the fight against malaria, researchers have found.

Several methods are currently used to reduce mosquito numbers and, as a result, malaria risk.

One is the use of an anti-parasitic medication called ivermectin. When mosquitoes ingest blood containing this medication, it shortens the insect’s lifespan.

But researchers say this medication is environmentally toxic and when it is overused to treat people and animals with parasite infections, resistance to the drug becomes a concern.

Now a study published in the journal Science Translation Medicine has identified another medication, nitisinone, which has the potential to suppress mosquito population and control malaria.

“One way to stop the spread of diseases transmitted by insects is to make the blood of animals and humans toxic to these blood-feeding insects,” said Lee Haines, associate research professor of biological sciences at the University of Notre Dame, honorary fellow at the Liverpool School of Tropical Medicine and co-lead author of the study.

“Our findings suggest that using nitisinone could be a promising new complementary tool for controlling insect-borne diseases like malaria.”

This medication is typically used for patients with a rare inherited disease — such as alkaptonuria and tyrosinemia type 1 — whose bodies struggle to break down the protein building block or amino acid tyrosine.

The drug works by blocking a type of enzyme called 4-hydroxyphenylpyruvate dioxygenase (HPPD). Blocking this prevents the build-up of harmful disease byproducts in the human body.

However, when a mosquito drinks blood containing the drug, it also blocks this HPPD enzyme in their bodies which prevents the insect from digesting the blood, causing them to die quickly.

Four people diagnosed with alkaptonuria donated their blood for the study, which was fed to female anopheles gambiae mosquitoes – the primary mosquito species responsible for spreading malaria in many African countries.

The researchers explored what concentrations of the drug are needed to kill mosquitoes and compared its effectiveness to the anti-parasitic medication ivermectin.

Nitisinone was shown to last longer than ivermectin in the human bloodstream and was able to kill not only mosquitoes of all ages — including the older ones that are most likely to transmit malaria — but also the hardy mosquitoes resistant to traditional insecticides.

Mosquitoes which were fed the drug first lost the ability to fly and then rapidly progressed to full paralysis and death, the study authors explain.

“In the future, it could be advantageous to alternate both nitisinone and ivermectin for mosquito control,” Dr Haines said. “For example, nitisinone could be employed in areas where ivermectin resistance persists or where ivermectin is already heavily used for livestock and humans.”

However, more research is needed to determine what dosage of the drug works the best.