By Kepher Otieno - Reporter
Kenya, 12 January 2026 - Even as global scientists announce yet another major breakthrough in the search for new malaria drugs, the frontline battle against Africa’s oldest killer is being fought in more humble places — the mud and brick walls of homes in western Kenya.
In Siaya County, one of the country’s malaria epicentres, the local government is preparing to unleash a quiet but powerful weapon: Indoor Residual Spraying (IRS), a strategy designed to wipe out mosquitoes where they rest and breed.
The County government, working with the U.S.-backed Presidential Malaria Initiative (PMI), has begun intensive capacity building of health workers ahead of a countywide IRS rollout scheduled to start next week.
The aim is brutally simple: kill the mosquitoes before they can kill people.
Siaya’s Public Health Director Ken Orwenjo says the urgency could not be clearer. Malaria prevalence in the county stands at a staggering 29 per cent — nearly five times the national average of six per cent.
“In 2023, we invaded mosquito breeding grounds in Madiany, Rarieda Sub-County, and now we are preparing to execute indoor residual spraying across the entire county to reduce malaria prevalence,” Orwenjo said.
His language is telling. This is not routine public health; it is a war against an enemy that is evolving fast. The anopheles mosquito, the main malaria vector, is no longer behaving the way scientists and control programmes once assumed.
“The mosquitoes transmitting malaria are evading traps set to deal with them. At times they are resistant to insecticides and have also changed their ways of life, now biting during the day instead of the night,” Orwenjo explained. “The anopheles mosquitoes that were biting at night have changed strategy and infect people during daytime.”
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That shift is undermining traditional defences such as bed nets, which are most effective when people are asleep. It is why IRS — which coats interior walls with long-lasting insecticides — is being pushed as a more aggressive and adaptive tool. When mosquitoes land on treated surfaces after feeding, they die, breaking the transmission cycle.
Malaria Control Coordinator Eunice Oreri said the spraying will begin in February 2026 and run until February 26, targeting every household in Siaya. She assured residents that the insecticides are safe for families, including pregnant women and young children.
“We want residents to embrace this initiative. Siaya stands to benefit immensely from it, especially because we are one of the counties that leads in malaria burden,” Oreri said.
The county is not acting on theory alone. Just across the border in Homa Bay, IRS slashed malaria prevalence from 27 per cent to just three per cent — a dramatic result that has made the strategy impossible to ignore.
IRS will complement other interventions, including the routine distribution of long-lasting insecticide-treated nets. In Siaya, pregnant women receive nets at antenatal clinics, while the entire population is covered every three years. The last mass distribution was in 2024, with the next planned for 2027.
The stakes are high. According to the Kenya Malaria Indicator Survey, if you sample 100 people in Siaya, 29 show signs of malaria. That is not just a health crisis; it is an economic and social one, draining households through lost productivity, hospital bills and school absenteeism.
As scientists in distant laboratories edge closer to new miracle drugs, Siaya’s approach is a reminder that breakthroughs only matter if the mosquitoes are first beaten back. In this county, the next battlefield is not a research lab — it is the living room wall.
