Countries that receive the most health aid also show fastest bed net distribution. Still, three-fourths of children remain unprotected from the deadly disease
August 17, 2010 - In countries susceptible to malaria, the number of households that own an insecticide-treated bed net – the chief defense against mosquitos – has grown 16 times over the past decade, according to new research from the Institute for Health Metrics and Evaluation (IHME) and collaborators at the World Health Organization and the US Centers for Disease Control and Prevention.
The research shows that countries in Africa have expanded bed net ownership from 2.2% of the at-risk population in 1999 to 32.8% in 2008. Over two years, some countries have gone from having almost no nets in homes to delivering bed nets to 60% or more of homes at risk. The study, Rapid scaling-up of insecticide-treated bed net coverage in Africa and its relationship with development assistance for health: A systematic synthesis of supply, distribution and household survey data, appears online today in PLoS Medicine and uses an innovative analytical approach to measuring the distribution of bed nets in 44 countries. The lead author was Dr. Abraham Flaxman, Assistant Professor of Global Health at IHME.
“What we have seen with bed nets is that rapid distribution of a public health intervention is possible on a large scale,” said Dr. Stephen Lim, an Associate Professor of Global Health at IHME and the paper’s senior author. “At the same time, there still remains a lot of work to be done to reach all the populations at risk of contracting malaria.”
By 2008, four countries were able to reach 80% or more of their at-risk populations with bed nets: Djibouti, Ethiopia, Sao Tome and Principe, and Mali. It is important, however, to interpret the numbers for countries such as Ethiopia cautiously as there is substantial uncertainty about the size of the population at risk of malaria.
The researchers also explored whether these bed nets were actually being used. Because children under the age of 5 are among the most susceptible to death from malaria, researchers measured the percentage of at-risk children that were reported to have slept under a net. In 1999, only 1.5% of children at risk slept under a net. By 2008, more than a quarter – 26.6% – of children slept under a net. In three countries, more than 80% of all children slept under a net: Djibouti, Ethiopia, and Sao Tome.
Countries that received the most health aid for malaria programs – including Kenya, Liberia, Rwanda, and Zambia – had the fastest scale-up of bed net distribution. In the 40 countries analyzed, there was a 5.3 percentage point increase in household bed net ownership for each US$1 per capita in health aid for malaria. In the case of bed net use among children under 5, there was a 4.6 percentage point increase.
“Global health funding to combat malaria has skyrocketed over the past two decades, and there have been questions raised about what we are buying with all of this money,” said Dr. Christopher Murray, Institute Director and one of the paper’s co-authors. “With malaria programs in sub-Saharan Africa, the results are clear: more money means more children sleeping under bed nets.”
In most countries that received the least funding for malaria prevention, the researchers found that bed net ownership and use remains low in large populations at risk. The researchers note, though, that their analysis only covered the period up to 2008 and that given how quickly bed net distributions have increased in some countries, the situation could have changed between 2008 and the present.
The method IHME developed to track bed nets has broad application to help study the scale-up of other global health interventions, including vaccines and medications. The method attempts to accurately estimate bed net ownership and use by using data from three different parts of the bed net supply chain: manufacturer reports of bed net deliveries to countries, National Malaria Control Program reports of bed nets distributed, and household surveys.
The new method is an adaptation of a “stock and flow model” that has been used in the past by companies to track products such as appliances and pharmaceuticals. Epidemiologists also have used the model to study the spread of infections in a population. IHME matched the model to the wide array of information available about bed nets, estimating trends in ownership and use even in countries that have sparse data.