Colorado State University researchers found that a drug used to treat river blindness in humans and heartworm in pets can kill mosquitoes carrying some forms of malaria, a disease that kills between 800,000 and 1 million people each year.

Researchers led by 39-year-old professor Brian Foy found that the number of mosquitoes carrying the deadliest strain of malaria dropped by 79 percent two weeks after people living in southern Senegal took ivermectin, a drug also used to treat scabies and head lice.

The discovery does not present a cure for the disease. People who are taking ivermectin can still contract malaria, but the research does suggest another way to prevent its transmission.

“It’s not a vaccine,” said David Sullivan, an associate professor at Johns Hopkins University who did not participate in the study. “It’s an additional tool that we can use.”

People living in malaria-prone areas often use bed nets to keep mosquitoes from biting at night, but that doesn’t help them when they travel outdoors or during the day, Foy and Sullivan said.

Foy hopes additional research, for which he’s currently seeking funding, will allow him to determine how long ivermectin will kill mosquitoes and whether the drug can be given in mass quantities to kill them.

The U.S. National Institutes of Health and the Bill and Melinda Gates Foundation provided funding for this latest leg of research, as did CSU.

Foy began his work in 2006. During the rainy season in 2008 and 2009, he and several colleagues from CSU traveled to Senegal, where they worked with Dr. Moussa Dieng Sarr, from the country’s Ministry of Health and Preventative Medicine, to monitor the mosquito populations.

Each day, the researchers awoke before sunrise to collect mosquitoes from the walls in homes of people who were taking ivermectin and those of people who weren’t taking it.

They spent their afternoons sorting the bugs, identifying their species and preparing some for shipment back to Colorado, where researchers would do more analysis.

They found that ivermectin paralyzes older, malaria-carrying mosquitoes within several hours, causing them to die. The younger mosquitoes can’t transmit malaria because the parasite needs 10 to 14 days in their systems to develop and move into the insect’s salivary glands for transmission. Only females feed on blood. Their adult life span is about a month.

“As long as you’re shortening the lives of the mosquitoes, they’re not going to transmit anymore,” Foy said, who also noted that “it’s fun to discover something that can help someone.”

Liz Navratil: 303-954-1054 or