Keep Out: Treated mosquito nets limit child deaths

By sleeping under chemically treated mosquito nets, children cut their risk of death almost in half, researchers in Kenya report. Their study, which included thousands of young children, bolsters the case that increased use of insecticide-coated netting can prevent malaria.

Treated nets repel mosquitoes that transmit malaria and fend off flies that carry other diseases. Carefully controlled studies had already shown that the nets could prevent disease in malarial areas of sub-Saharan Africa, but experts were unsure whether real-world use of treated nets would actually lower death rates.

Epidemiologist Greg W. Fegan and his colleagues at the Kenyan Medical Research Institute in Nairobi monitored 3,484 children in 72 towns and villages to examine the impact of recent net-distribution campaigns in parts of Kenya. In 2004, just 7 percent of children under age 5 in these malarial zones were sleeping under nets. By 2006, subsidized sales and giveaway programs had upped that rate to 67 percent.

The researchers monitored use of the nets for an average of 21 months per child, visiting the homes periodically. They recorded 100 deaths from any cause among children between 1 month and 5 years of age. They excluded infants less than a month old from the analysis, because such neonates often die of causes other than malaria. Of the 100 deaths, 81 occurred among children who slept without the protection of treated nets, the scientists report in the Sept. 22 Lancet.

After statistical adjustment, the authors estimated that children sleeping under nets were at 44 percent lower risk of death than unprotected children were. For every 1,000 nets distributed and used regularly, 7 child deaths can be averted, the authors calculated.

“With this work, the use of insecticide-treated bed nets is confirmed as a major child-survival intervention,” declare Christian Lengeler and Don deSavigny of the Swiss Tropical Institute in Basel, writing in the Lancet.

The nets had been treated with insecticides that are approved for human use. While some insecticide treatments need to be reapplied periodically, others last for the lifetime of the net.

On the basis of this study and earlier research, the World Health Organization this month endorsed distribution of nets treated with long-lasting insecticide, specifically targeting infants and pregnant women.

Meanwhile, governments and nongovernmental health agencies are now grappling with distribution alternatives. “It’s all about whether the nets are seen as a public good, like vaccines, and should be heavily subsidized and/or delivered for free,” says Katherine C. Macintyre, an infectious-disease researcher at Tulane University in New Orleans.

Donor agencies should regard resources devoted to subsidized or free distribution of treated nets as “money well spent” and recognize that the challenge is now to maintain and increase funding to expand such coverage, Fegan and his colleagues conclude.

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