Collaboration in Civic Spheres

New UW study assesses “net benefits” in African malaria fight

by Matt Rosenberg September 21st, 2011

SUMMARY: Working with U.S. and African colleagues, researchers from the University of Washington’s Institute For Health Metrics and Evaluation, in Seattle, integrated data from several dozen qualifiying health surveys in malaria-prone Sub-Saharan Africa and found that the use of Insecticide-Treated Nets helped actually reduce parasitemia and death in young children to a significantly greater degree than previously estimated in clinical trials. Their research, recently published in a peer-reviewed “open access” (online, free) medical journal and funded by the Bill and Melinda Gates Foundation, concludes that the use of the treated nets should be continued and expanded in Sub-Saharan Africa, where the bulk of the world’s one million annual deaths from the parasitic disease of malaria occur.


  • Malaria is transmitted through the bites of night-flying mosquitos which cause parasites to reproduce in red blood cells. The annual death toll of about one million people per year occurs mostly in Sub-Saharan Africa. Insecticide-Treated Nets used in homes and especially for sleeping can prevent malaria. Clinical trials showed treated nets could cut parasitemia – the presence of parasites in the blood – among young children by about 13 percent and deaths of children about 18 percent. Efforts to widely distribute treated nets have been underway for several years, and are supported by organizations including the World Health Organization, and the World Health Assembly. The Bill and Melinda Gates Foundation has also taken an especially prominent role in combatting malaria, through strategies including distribution of treated nets and support for research on a malaria vaccine, as The Seattle Times has reported.
  • However, there has been a knowledge gap in getting reliable data from the field on exactly how well Insecticide-Treated Nets are helping to reduce parasitemia and malaria in Sub-Saharan Africa. One big challenge is that because of poor health information systems in the most-affected nations, there’s little or no accurate official recorded data on rates of malarial illness and deaths. So a team of researchers from the University of Washington, the University of Pennsylvania and the University of Zambia was able to take an important step forward in quantifying the benefits of treated nets. Drawing from 29 demographic and health surveys in 22 Sub-Saharan countries and six malaria indicator surveys in seven countries, they synthesized data on treated net use with data on the prevalence of parasitic disease and deaths in young children. The Gates Foundation provided funding support for the study but according to the authors, “had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.”

KEY LINK: “Net Benefits: A Multicountry Analysis of Observational Data Examining Associations Between Insecticide-Treated Mosquito Nets And Health Outcomes,” Sept. 7, 2011, in PLoS Medicine, a peer-reviewed open access scientific journal of the Public Library of Science. Lead author, Stephen S. Lim, Institute for Health Metrics and Evaluation, University of Washington, Seattle. Co-authors include Christopher J.L. Murray, the Institute’s director.


  • The “pooled relative reduction” in the prevalence of parasitemia among children less than five years of age in Sub-Saharan African households which owned at least one Insecticide-Treated Net (ITN) was 20 percent.
  • Actually sleeping underneath a treated net was associated with a 24 percent reduction in the prevalence of parasitemia among children under five years of age.
  • Households that owned at least one treated net saw a pooled relative reduction of 23 percent in deaths of children aged one month to five years.
  • Researchers for the study concluded that their findings from actual health surveys of affected populations showed that the association between ownership and use of Insecticide-Treated Nets with reductions in parasitemia and deaths in young children was even greater than in clinical trials.
  • The findings do have some limitations. For instance, factors not accounted for in the field surveys may also have influenced the findings – such as extent of public education on how to effectively use treated nets, presence of skilled health care aides at births, and whether or not children received immunizations. Future inquiries should attempt to include such factors, if reliable data are available.
  • Nonetheless, the findings “support continued efforts to scale up (Insecticide-Treated Net) coverage in Sub-Saharan Africa and highlight the importance of maintaining (treated net) coverage in countries that have already successfully scaled up coverage.” Governments, NGOs, funding agencies and researchers should continue to coordinate related efforts.

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