NPR recently ran a story on a new use for a fairly well-known drug, ivermectin. If you have a dog or cat (or horse or sheep), you might well have used ivermectin to treat fleas or worms. But apparently, when taken orally in larger doses, it can make human blood lethal to malaria-carrying mosquitoes:
it’s a tantalizing possibility, according to research published this week in the journal The Lancet Infectious Diseases. The study points to a potential new tool to fight malaria: the medication ivermectin. Studies conducted in the 2000s, including one in 2010, show that malaria-carrying mosquitoes die after feeding on individuals who have ingested the drug.
Malaria is a mosquito-borne infection that affects more than 200 million people worldwide.
“Since 2015, the number of annual deaths from malaria has stabilized,” says Menno Smit, MD, a Ph.D. candidate at the Liverpool School of Tropical Medicine who led the new study. “We’re not making any more progress. We need new tools, and ivermectin could be one.”
Ivermectin was developed in the early 1980s as a drug to fight parasites that cause river blindness and elephantiasis. Smit and his colleagues hope it can also help eradicate malaria.
In their study, the researchers demonstrate that three high doses of ivermectin make human blood deadly to mosquitoes for up 28 days after the third treatment. This high dose of ivermectin was also well-tolerated with few side effects.
To reach these conclusions, researchers at the Jaramogi Oginga Odinga Teaching and Referral Hospital in Kenya gave 47 participants 600 miligrams of ivermectin in tablet form for three days in a row. Blood samples were obtained from these participants six times and then fed to mosquitoes in cages.
“We put the blood in an artificial membrane that mosquitoes could bite on and then watched,” Smit explains. “Most died within a week after [drinking] the blood.”
Two weeks after feeding, 97 percent of the mosquitoes had died.
In this study, Smit says the high dosage of 600 milligrams for three days was well-tolerated. Participants reported few side effects, though he admits everyone in the study was already hospitalized and receiving treatment for malaria.
“The patients may have noticed less side effects because they were already feeling sick,” Smit explains. “We have yet to see if the excellent tolerance we saw would be just as good in healthy individuals.”
You can read the Lancet study here.