JOHANNESBURG, South Africa — As a boy in remote western Kenya, Fredros Okumu sat under the stars, smothered by the smoke of the family fire, until it was time to go to bed.

Even now, when he returns home to his village as a 29-year-old man who left and achieved things, he still sits in the darkness, eyes stinging, nose running, enveloped in the choking smoke. Its smell clings to his hair and clothing, but at least it serves its purpose: keeping the mosquitoes at bay.

Like almost everyone in the village of Uyoma, Okumu lost family and friends to mosquito-borne malaria when he was growing up. So the smoke of burning Kenyan bush herbs was his friend.

“One of the things growing up, I caught malaria at least twice a year. I lost cousins, around five of them. And if you speak to any African boy who is 29 years old and grew up in an African village, he would either have a similar situation, or worse,” he said in a phone interview from Tanzania, where he works as an entomologist for the Ifakara Health Institute, a medical and public health research institute.

Mosquitoes responsible for spreading malaria, such as the female Anopheles varieties, are particularly attracted to feet.

In a splendid example of African inventiveness, Okumu is developing a toxic mosquito trap for African villages that attracts the insects using a human scent that mosquitoes apparently cannot resist: smelly socks.

After his mentor, a Dutch medical entomologist, discovered the insects have an affinity for foot odor by standing naked in a room full of mosquitoes and seeing where they bit him, Okumu was driven to find a cheap, practical way to use the knowledge. His plan would enlist villagers who would wear cotton pads in their socks, to be used as bait in mosquito traps, a cheaper option for villages than using chemically synthesized foot odor.

The project, which has received $775,000 in funding from the Bill & Melinda Gates Foundation and Grand Challenges Canada, is designed to eradicate mosquitoes outdoors, to complement the big strides made in cutting malaria deaths using treated bed nets, malarial drugs and spraying.

“We believe African innovators are best placed to solve African problems,” said Peter Singer of Grand Challenges Canada, which seeks out African inventors with out-of-the box ideas. “I think there’s a lot of value at the table in terms of tapping bright young African innovators who have great ideas and who could be more fully enabled to tackle their own challenges.”

Some African countries have seen dramatic reductions in malaria rates by employing a raft of control techniques. Malaria deaths were cut by about 50 percent in nine African countries between 2006 and 2008, according to the World Health Organization, including Tanzania, Zambia, Ethiopia, Rwanda and Ghana. But there were still 243 million cases of malaria worldwide in 2008 and 863,000 deaths, mostly among children — with Africa accounting for 90 percent of malaria deaths.

It was Knols who discovered that mosquitoes were most attracted to smelly feet. But Okumu decided to apply the discovery to an outdoor mosquito trap.

Okumu’s plan to use actual smelly socks odor offers a cheap alternative to a chemical smell and can be easily replaced by villagers. He plans to focus on youths playing soccer, or laborers, as a source for the sock pads.

“We hope this will reduce the cost but also create a level of interest in the community,” he said.

The mosquito trap is a wooden box with louver vents and a battery-run fan to blow the sock odor into the air through a bamboo pipe.

The next phase of his research is to figure out the best places in the village to post mosquito traps and develop a trap that will cost only a few dollars.