Study Finds Ivermectin Effective Against Malaria-Spreading Mosquitoes

The drug can also potentially block the development of malaria-causing parasites in infected mosquitoes.

Researchers also found that contact-exposure to ivermectin has the potential to block the development of Plasmodium parasites, which are responsible for malaria, in infected mosquitoes. File photo

Ivermectin was found to be highly toxic against certain mosquito types and can be used as an effective tool in malaria management, according to a peer-reviewed study published in Nature on Oct. 31.

Ivermectin became controversial during the COVID-19 pandemic when many health officials denounced its usage, while others praised the drug for its efficacy. Since its discovery in the late 1970s, it has been used worldwide for treating infections caused by gastrointestinal roundworms, lungworms, and other parasites.

Many regions in Africa have been using ivermectin for malaria management, and in places where there was mass drug administration, it has been observed to “significantly reduce” the mosquito population, the study said.

Researchers based in India looked at the potential of ivermectin as a “contact-toxin” for malaria transmitters and parasites. Contact toxins are toxins that are absorbed through direct skin contact.

The study exposed lab-reared female An. culicifacies and An. stephensi mosquitoes to varying concentrations of ivermectin. Both mosquito types are the major malaria vectors in India.

When ivermectin was administered to the mosquitoes, researchers found that there was “significantly high mortality” depending on the drug concentration and the method of administration.

Mortality rate climbed as dosage was raised, with the highest ivermectin concentration resulting in a 100 percent mortality rate.

“This study also pin-pointed the fact that ivermectin when applied to treated surfaces exhibited faster killing effect among mosquitoes in contrast to when ingested through blood meal from treated individuals,” it said.

“When feeding on ivermectin-treated blood, mosquitoes survived an average of 7 days. Ivermectin exhibited a significantly stronger and faster mosquito-killing effect when applied to treated surfaces, eliminating mosquitoes within 24–48 h.”

Researchers also found that contact-exposure to ivermectin has the potential to block the development of Plasmodium parasites, which are responsible for malaria, in infected mosquitoes. They suggested that ivermectin impairs the sexual development of the parasite inside the mosquitoes’ midgut.

“The results of this study highlight the potential of ivermectin as a promising synergist to traditional insecticide-based vector control strategies. This transmission-blocking activity adds an important dimension to ivermectin’s potential as a malaria control tool,” the study said.

The study was funded by the Indian Council of Medical Research—National Institute of Malaria Research, the University Grants Commission, and the Council of Scientific and Industrial Research. The authors declared no competing interests in the study.

Among previous studies, some have questioned the efficacy of ivermectin to treat malaria in humans, while others have confirmed its positive impact,

In a June 2021 study published in the Cochrane Library, researchers detailed the results of a test conducted in eight villages in the West African nation of Burkina Faso, where people received doses of ivermectin.

Researchers concluded that the study did not demonstrate ivermectin’s effect on the cumulative incidence of malaria among children during the 18-week study period.

“We are uncertain whether community administration of ivermectin has an effect on malaria transmission,” they wrote.

Another study, published in The New England Journal of Medicine on July 23, found ivermectin to be beneficial for malaria treatment. It analyzed children, aged 5 to 15, living in a Kenyan county where malaria was endemic and the use of insecticide-treated bed nets was high.

Administering a dose of ivermectin once a month for three straight months was found to have led to a 26 percent lower incidence of malaria infection compared to a control drug.

Malaria Worldwide

According to a December 2024 post by the World Health Organization (WHO), globally in 2023, there were an estimated 263 million malaria cases and 597,000 malaria deaths in 83 countries.

“The WHO African Region carries a disproportionately high share of the global malaria burden. In 2023, the WHO African Region was home to 94 percent of malaria cases (246 million) and 95 percent (569 000) of malaria deaths,” it said.

In the United States, malaria is not endemic, meaning it does not regularly occur or spread in the country. Approximately 2,000 malaria cases are reported annually in the country, according to the Centers for Disease Control and Prevention.

Ivermectin During Pandemic

During the COVID-19 pandemic, some researchers promoted ivermectin as a potential treatment for the illness, despite federal officials not approving it.

In an August 2021 X post, the Food and Drug Administration asked people to stop using ivermectin. “You are not a horse. You are not a cow. Seriously, y’all. Stop it,” it said, referring to the fact that ivermectin is commonly used as a veterinary medicine.

A June 2021 study found ivermectin to be associated with “large reductions” in COVID-19 deaths.

According to researchers, the risk of death among people hospitalized with COVID-19 who were treated with ivermectin was 2.3 percent compared to 7.8 percent among those who did not receive the drug.

Another 2022 study examining ivermectin use in COVID-19 patients found that it resulted in decreased mortality compared to remdesivir, the medication federally authorized by the FDA for emergency use to treat COVID-19.

In recent years, some states in the United States have moved to allow ivermectin to be sold as an over-the-counter medication. In 2022, Tennessee permitted the sale of ivermectin without a prescription requirement. Arkansas and Idaho followed suit this year.

Potential side effects of ivermectin include vomiting, nausea, constipation, loss of appetite, chest discomfort, and weakness. Some of the serious consequences include coma, hives, peeling skin, and confusion.

As of now, the FDA hasn’t approved ivermectin as a treatment for COVID-19.

“The FDA has not authorized or approved ivermectin for the treatment or prevention of COVID-19 in people or animals. The FDA has not determined that ivermectin is safe or effective for these indications (uses),” the agency stated on its website.