A Controversial Drug Finds a New Target: Malaria-Carrying Mosquitoes
A decades-old antiparasitic drug once thrust into controversy during the COVID-19 pandemic may be on the verge of a scientific redemption story. Ivermectin, long used to treat parasitic infections in humans and livestock, is now showing surprising potential in the fight against malaria — one of the world’s deadliest diseases.
According to a new study published October 31 in Nature, researchers have found that ivermectin is highly toxic to certain species of mosquitoes that transmit malaria. Even brief contact with the drug proved lethal, and more importantly, it also disrupted the development of Plasmodium — the parasite responsible for malaria — inside infected mosquitoes.
An Old Drug, a New Purpose
Ivermectin’s history is complicated. Discovered in the late 1970s, it revolutionized the treatment of parasitic infections in humans and animals and earned its discoverers a Nobel Prize. But its reputation took a hit during the COVID-19 pandemic, when unproven claims about its antiviral properties sparked heated public debate and regulatory backlash.
Now, researchers are exploring a very different question: could ivermectin be repurposed not to treat infection in humans, but to stop mosquitoes themselves?
In parts of Africa where ivermectin has been used for decades to combat parasitic worms through mass drug-administration programs, health officials began noticing an unexpected side effect — mosquito populations were declining. That observation prompted scientists to investigate whether the drug could act as a vector-control tool, complementing insecticides and mosquito nets.
Inside the Indian Study
In the new study, Indian researchers tested ivermectin’s effects on Anopheles culicifacies and Anopheles stephensi — two primary malaria vectors in the region. Laboratory results were striking: mosquito mortality increased steadily with higher ivermectin concentrations, reaching 100% death rates at peak exposure.
Interestingly, the method of contact made a big difference. Mosquitoes exposed to ivermectin-coated surfaces died within 24 to 48 hours, while those that ingested the drug through treated blood survived up to a week.
But the study’s most intriguing finding went beyond toxicity. Ivermectin appeared to interfere with the s*xual development of the malaria parasite inside the mosquito’s gut, potentially blocking transmission entirely.
“The drug seems to act on two fronts — it kills the vector and cripples the parasite,” the researchers wrote. They suggested ivermectin could complement traditional insecticide programs by adding a transmission-blocking layer to existing malaria-control efforts.
The work was funded by the Indian Council of Medical Research, the University Grants Commission, and the Council of Scientific and Industrial Research, with no reported conflicts of interest.
A Mixed Record
Not all studies have found consistent results. A 2021 trial in Burkina Faso showed no significant reduction in malaria among children after mass community dosing, while a 2023 study in Kenya reported a 26% decrease in infection rates among children after three months of regular ivermectin treatment.
Experts caution that while ivermectin’s mosquito-killing properties are clear, its practical use in large-scale malaria control will depend on dosage, timing, and environmental factors.
A Global Health Imperative
Malaria remains one of the most persistent global health challenges. The World Health Organization reported 263 million cases and nearly 597,000 deaths in 2023, with Africa accounting for the vast majority — 94% of all cases and 95% of deaths.
Though malaria has been largely eradicated in the United States, about 2,000 travel-related cases are still reported each year.
During the COVID-19 pandemic, ivermectin once again entered the public spotlight as some promoted it as a treatment for the virus. However, the U.S. Food and Drug Administration maintains that ivermectin has not been authorized or approved for preventing or treating COVID-19. The drug, while safe in prescribed doses, can cause side effects such as nausea, weakness, confusion, or severe allergic reactions when misused.
Conclusion
While ivermectin’s past is marked by controversy, its future in malaria control could be transformative. Early evidence suggests it might do what few tools can — kill mosquitoes and block malaria transmission simultaneously.
If further trials confirm these findings, ivermectin could join the front lines of global malaria eradication efforts, turning a once-debated drug into a surprising ally against one of humanity’s oldest and deadliest foes.