What makes ivermectin a candidate for malaria control
Malaria control hinges on reducing both the human parasite reservoir and the mosquito population that spreads it. Ivermectin, a long‑used antiparasitic, works inside the human body and can render mosquitoes dead or less able to transmit malaria after they feed on treated individuals. This unique mechanism distinguishes it from bed nets and indoor spraying, which primarily target mosquitoes indoors and at night. Mass drug administration (MDA) with ivermectin could, in theory, shrink the human reservoir while simultaneously delivering a lethal inside-out blow to mosquitoes that bite treated people.
The BOHEMIA trials: Kenya and Mozambique
Kenya results
The BOHEMIA trial, conducted in Kwale County, Kenya, enrolled children aged 5–15 and compared monthly ivermectin dosing against a placebo-based control for more than three months. The study, published in The New England Journal of Medicine, reported a 26% reduction in malaria cases in the ivermectin group. This exceeded the World Health Organization’s 20% threshold for considering a tool potentially useful in public health programs. Importantly, the community-wide impact appeared stronger for children living farther from untreated areas, suggesting a meaningful herd effect. More than 56,000 doses were deployed, and side effects were generally mild and short-lived.
Mozambique results
In Mozambique, the same sterile testing framework aimed to evaluate whether added ivermectin could further cut transmission alongside existing measures. However, operations faced operational shocks from Cyclone Gombe and a cholera outbreak, complicating interpretation and limiting conclusive results. While the trial demonstrated safety in the field, its disruption prevented a clear assessment of ivermectin’s added value in reducing malaria prevalence there.
The MATAMAL trial in Guinea-Bissau
Findings and interpretation
Guinea-Bissau hosted the MATAMAL trial, enrolling over 25,000 people across 24 villages to test whether adding ivermectin to the standard anti-malarial drug regimen would improve outcomes. Unlike the BOHEMIA results, MATAMAL did not show a significant difference in malaria prevalence between villages that received ivermectin and those that did not. In fact, there were slightly more malaria cases in the ivermectin group, with no clear signal of enhanced mosquito suppression. Researchers suggest that timing, dosing, or interaction with existing therapies may have limited the potential benefit in this setting.
Safety, resistance, and practicalities
Across trials, ivermectin’s safety profile has been favorable for large campaigns, with most adverse events being mild headaches or dizziness and no serious safety signals reported in participants not excluded by trial design (e.g., pregnant women or very young children in some arms). Yet resistance looms as a possible constraint. A 2024 review highlighted growing resistance in non-human parasites and underscored the limited data on ivermectin’s impact on Anopheles mosquitoes. If resistance emerges, the utility of ivermectin for malaria could wane, especially with widespread use in treating other parasites in humans and animals.
What this means for malaria control programs
Ivermectin should be viewed as a potential complement to established tools—bed nets, indoor residual spraying, and vector control measures—rather than a stand-alone solution. Its inside-the-body action means it could target mosquitoes biting outdoors or at times when conventional tools are less effective. Delivery through existing deworming campaigns or community health initiatives offers a practical entry point, particularly in hard-to-reach settings. However, mixed trial results emphasize the need for careful planning on timing, dosing, and integration with vaccines or novel vector-control approaches.
Looking ahead: next steps in research
Researchers are pursuing longer-lasting formulations, optimized dosing schedules, and potential combinations with vaccines or genetically modified mosquitoes. Ongoing trials and robust resistance surveillance will shape whether ivermectin becomes a routine component of malaria control. In the meantime, strengthening multi-pronged strategies remains essential as countries strive to sustain progress and protect vulnerable communities from malaria’s continuing burden.
