Mosquitoes, drugs and a lingering idea: the story behind the biggest essay on ivermectin against malaria

In 2007, a young Venezuelan doctor - CarlosChaccour, a researcher at the University of Navarra - spent more than three years working in indigenous communities in the Amazon "in places that could only be reached by plane", where he had great exhibition to tropical diseases and those of poverty and rural areas. His interest in helping people fight these diseases, which require funding and time, has continued ever since. He received a scholarship from philanthropist Ricardo Cisneros and aChevening scholarship from the British government to study for a Master's Degree at the London School of Hygiene and Tropical Medicine and, subsequently, he took the spanish medical residency program and obtained a place at the Clínica Universidad de Navarrawhere he also completed his doctorate on the potential use of Ivermectin as a complementary strategy for malaria elimination. Chaccour wondered whether it was possible to combat malaria not only with mosquito nets or insecticides, but with a drug that would act from within: ivermectin, an antiparasitic that, when ingested by humans, is lethal to the mosquitoes that bite them. 

Seventeen years later, this physician is leading the largest clinical essay ever conducted on the use of ivermectin to control malaria, which is coordinated by ISGlobal. The results, published in July 2025 in the New England Journal of Medicinemark a turning point. The study demonstrates that administering ivermectin to an entire population, in parallel to the use of bed nets, significantly reduces transmission of the disease. Specifically, 26% fewer new infections in children aged 5 to 15 years. "Ivermectin has shown great potential to reduce malaria transmission and could complement existing control measures. With further research, it could become an effective tool to control and even contribute to the elimination of malaria," says Chaccour.

An idea that has been a long time coming

Since 2016, progress against malaria has stalled. Mosquito resistance to insecticides and their behavioral changes - they bite at dawn, in the open air, when people are not protected - have eroded the effectiveness of available tools. In this context, ivermectin offered an alternative route. But for years, conclusive evidence was lacking. "We knew that ivermectin killed mosquitoes for decades," notes Chaccour. "But if this disease were not a neglected disease, something would have been done about it by now."

The BOHEMIA (an acronym for Broad One Health Endectocide-based Malaria Intervention in Africa) essay was born to fill this gap. Funded by Unitaid with $27 million and coordinated by ISGlobal, with partners in Africa, Europe and the Americas, the study was deployed in two regions with a high malaria burden: Kwale County, on the coast of Kenya, and the rural district of Mopeia, in Mozambique.

In Kwale, 28,932 people in 84 communities received an ivermectin (or, in the control group , albendazole) tablet once a month for three months. In parallel, the coverage of treated bed nets was maintained. Follow-up focused on children aged 5 to 15 years. The result? A clear difference: the ivermectin-treated group had a 26% lower incidence of malaria. "These are data that meet WHO criteria for new vector control tools," says Marta Maia, an entomologist at the University of Oxford and co-principal investigator of the study.

Safety was another core topic: more than 56,000 treatments were administered without serious adverse effects attributable to the drug. Most of the reactions were mild and known from previous use in campaigns against diseases such as onchocerciasis or filariasis.

In addition, as a side effect, communities reported a drop in the presence of bedbugs. In Mozambique, where the study was interrupted by Cyclone Gombe and a cholera outbreak, a significant decrease in scabies and lice was also observed.

More than a pill: a paradigm shift

Unlike conventional strategies, ivermectin does not act as a barrier, but as a lethal trap. Its advantage lies in its versatility: it can be integrated into existing health programs and, in addition to attacking malaria, it combats other neglected diseases at the same time. "Thanks to its innovative mechanism of action and a widely proven safety profile , ivermectin can become a powerful complementary option that leverages a safe and well-known drug to reinforce existing control strategies," says Regina Rabinovich, director of ISGlobal's Malaria Elimination Initiative and co-principal investigator of the study with Chaccour.

WHO has already evaluated the data from the study. The group advisor on vector control recommended further research. The findings have also been shared with local governments in Kenya and Mozambique for possible application in national programs.

The future is not yet written

The BOHEMIA results are not a goal line, but a sign that progress is possible. Chaccour, Maia and their team now hope to generate new data that will facilitate the political decision to incorporate this tool in real contexts. "What would not be acceptable is for this evidence to remain on paper," warns Chaccour, who is currently a resident researcher at the Navarra Center for International Development (NCID) at the University of Navarra, a research center whose goal is to contribute to publicdiscussion on development. "Lives are at stake," concludes the Venezuelan doctor.

Meanwhile, in a corner of Kenya, thousands of children have spent a rainy season with fewer bites and less fever. They may not know that it all started with an old idea and a pill. But the echo of that story has finally reached far and wide.