In a project that is being hailed as a model for other African countries, Kenya's ministry of health has distributed 13.5m insecticide-treated nets (ITNs) across the country since 2003. As a result, the number of children sleeping under a net increased from 5% to 52% in less than five years.
The scale of the distribution is unprecedented in Africa, where malaria kills 1 million people a year, more than any other disease. In Kenya 34,000 people die after being bitten by mosquitoes every year, and the average family spends $20 on treatment.
Early results from the Kenyan programme, which was supported by the WHO and Britain's Department for International Development, show that in some areas the number of childhood deaths from malaria has fallen by 44%. Three hospitals in the malarial-prone coastal areas reported a drop in admissions of 57% in 2006, compared with 1999.
Dr Willis Akhwale, head of malaria control at the health ministry, said: "We have shown that the war on malaria can be won."
It has long been known that ITNs are one of the most effective ways to prevent malaria, but the distribution of nets across Africa has been low because of a lack of funding and capacity at both donor and government level, as well as disagreement on distribution methods.
The Kenyan project began with the sale of heavily subsidised ITNs through health clinics and the retail sector - a technique known as "social marketing". Some in the scientific community believed that only when people made an investment in the net could usage be guaranteed. In the past, nets given away have often been resold, used for fishing, or simply discarded when the insecticide wore off.
But WHO officials involved in the current programme said that in Kenya the poorest could still not afford the subsidised ITNs. Only after government gave away 3.4m long-lasting nets to the most vulnerable people did the drop in deaths become clearly evident.
Dr Arata Kochi, the WHO's head of malaria, described the findings as "highly significant". Speaking in Nairobi yesterday, he announced that the WHO had issued new guidelines on ITNs. Not only should they be given away, he said, but all community members should be targeted rather than only pregnant women and children under five, who have previously been the main beneficiaries of ITN campaigns.