Veronica Njeri, 45, says she has "never healed" since losing two of her six children to malaria 20 years ago, and she still feels vulnerable. While her oldest are adults or teenagers, and have presumably built up immunity to the disease, she worries about her youngest, Anthony, who is 4.
But since hundreds of free mosquito nets came to Maendeleo, her rice-farming village in west-central Kenya, "malaria epidemics have become rare," she said happily, even though the village sits amid stagnant paddies where swarms of mosquitoes breed.
Villages like Maendeleo are at the center of a debate that has split malaria fighters: how to distribute mosquito nets.
Recently, Dr. Arata Kochi, the blunt new director of the World Health Organization's malaria program, declared that as far as he was concerned, "the debate is at an end." Virtually the only way to get the nets to poor people, he said, is to hand out millions free.
In doing so, Dr. Kochi turned his back on an alternative long favored by the Clinton and Bush administrations — distribution by so-called social marketing, in which mosquito nets are sold through local shops at low, subsidized prices — $1 or so for an insecticide-impregnated net that costs $5 to $7 from the maker — with donors underwriting the losses and paying consultants to come up with brand names and advertise the nets.
"The time for social marketing of bed nets in a big way is over," Dr. Kochi said in an interview. "It can become a supplemental strategy for urban areas and middle-income countries."
Two years ago, social marketing was at the heart of a scandal when it was revealed that the United States Agency for International Development, or USAid, which distributes foreign aid, was spending 95 percent of its malaria budget on consultants and 5 percent on goods like nets, drugs and insecticide. Under attack from several senators championing the fight against malaria, the agency later announced that it would spend at least half its budget on goods.
Senator Tom Coburn, Republican of Oklahoma, called the new W.H.O. policy "a great move," adding, "We knew social marketing doesn't work."
In practice, nothing much had been working. In 2000, a world health conference in Abuja, Nigeria, set a goal: by 2005, 60 percent of African children would be sleeping under nets. By 2005, only 3 percent were.
The theory behind social marketing, which is also used to distribute condoms and oral rehydration salts, is that the poor see more value in brand-name goods they pay for than handouts they get free, and that the trade creates small entrepreneurs.
The usual comparison made is to Coca-Cola, which reaches Africa's remotest corners. But Dr. Kochi rejected that model, saying, "I'm not sure whether the poorest of the poor actually drink Coca-Cola."
He argues that the insecticide-filled nets, when used by 80 percent or more of a village, create a barrier that kills or drives off mosquitoes, protecting everyone in the area, including those without nets. Individual nets tended to just drive mosquitoes next door, to bite someone else. As such, he said, nets ought to be treated as a public good, like the measles or polio vaccines, which the world does not charge the poor for.
Free net distributions are usually done in a week or two, by armies of workers who are paid a few dollars a day by the Red Cross or health ministry to cover a country or other large region. Distributions have been tried in Sierra Leone, Niger, Togo and elsewhere, sometimes in conjunction with measles shots or deworming drugs.
The new model is beginning to prevail but has not completely swept the field. Some donors still use some social marketing. Unicef, the world's largest buyer of nets, distributed 25 million last year, of which 92 percent were given away, said its medical director, Dr. Peter Salama. The main American program, the President's Malaria Initiative, plans to hand out more than 15 million nets by 2008, of which about 75 percent will be free, said its coordinator, Rear Adm. Tim Ziemer.
In June, Admiral Ziemer and the first lady, Laura Bush, who has made malaria her crusade, helped hand out 500,000 free nets in Mozambique and Zambia.
Social marketing may be useful during gaps between mass distributions, said Trent Ruebush, a malaria expert at the initiative and USAid. The best insecticide-filled nets last three to five years, but babies will be born in that time, or new families will move into an area. "We feel it is one of various effective ways to go," Dr. Ruebush said.
Experiences in Kenya played a large part in persuading the W.H.O. to change its policy, said Dr. Peter Olumese, a medical officer in the agency's malaria program.
Maendeleo, a village of about 140 mud-walled shacks with tin roofs, was part of a five-year study of 40 health districts. When it started in 2002, the only nets were those for sale in small shops, Dr. Olumese said, and only about 7 percent of people had them.
Social marketing was introduced by Population Services International, a large aid contractor. That increased coverage to about 21 percent by early 2006.
Then, late last year, the health ministry got a big grant from the Global Fund to Fight AIDS, Tuberculosis and Malaria that allowed it to hand out 3.4 million free nets in two weeks. Coverage rose to 67 percent, and distribution became more equitable. Under social marketing, Dr. Olumese said, the "richest of the poor" had 38 percent coverage, while the "poorest of the poor" — like Maendeleo's rice farmers — had only 15 percent. After the handouts, they were about equal.
Deaths of children dropped 44 percent.
It also turned out to be cheaper, Dr. Olumese said. With consultant fees, transportation, advertising and shipping, social marketing added about $10 to the cost of each net beyond the $5 to $7 that Danish or Japanese makers charged. But even with payments to volunteers, the added cost of free distribution was only about $1.25 per net.
"There has been a paradigm shift," Dr. Olumese said. "We need to use the momentum we have right now."
Between the giveaways, he said, nets should be handed out free to all pregnant women and mothers who visit health clinics. Some women struggle to afford even the 10 cents per child cost of identity cards that let them visit clinics. "Asking a mother to make a decision to feed her child or buy a net is not fair," he said.
In Maendeleo, a village elder, Benson Gacu, confirmed that price was a major impediment. "Our people are poor, and very few could afford to buy a mosquito net even for 50 shillings," or about 75 cents, he said. "We are happy that the nets are free."
Francis Mureithi, a local shopkeeper, said he still had some 50-shilling nets for sale because the government had given free ones only to families with children under 5.
But, Mr. Mureithi noted, sales of malaria pills were way down.