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See Inside January 2008

A Better Mosquito Net

Fighting malaria will require more innovative defenses



MATT COLLINS

Malaria remains one of the world’s great scourges, striking more than 500 million people every year. The groups most at risk are pregnant women and children younger than five years old. In sub-Saharan Africa, 20 percent of all childhood deaths are from malaria. Pregnant women who contract the mosquito-borne disease can develop severe anemia and give birth to underweight babies. The World Health Organization estimates that 10,000 pregnant woman and 200,000 infants in Africa die from malarial infections every year.

To combat the disease, many development agencies have focused on distributing mosquito nets that would protect Africans from being bitten while they sleep. This strategy has resulted in a huge upsurge in the number of bed nets supplied to the population as a whole and particularly to pregnant women and young children. The widespread distribution, however, has not resulted in a significant decrease in malaria. Many doctors in sub-Saharan Africa attribute the failure to an overreliance on nets in lieu of other interventions, such as the indoor spraying of dwellings with insecticide. Other experts say the problem is the misuse of mosquito nets; there is anecdotal evidence that some people have employed the nets as wedding veils or fishing aids. Some economists argue that charging a small fee for the nets would increase the likelihood that they would be used appropriately. Others claim such a fee would prevent a large part of the population from receiving nets. These are valuable debates. Before delving into behavioral economics, though, it might be useful to consider a more basic problem: the mosquito nets are poorly designed.

The bed nets distributed by governments and international organizations have one of two basic designs: circular or rectangular. The circular design hangs from the ceiling by one string, with the net fanning out from a ring at the top and tucked tightly under the mattress on all sides. The rectangular design ties to the ceiling with four strings and hangs straight down on all sides of the bed, with the fringes again tucked under the mattress. Both designs work well for middle-class homes with flat ceilings and a bed for every member of the family. But most of the poor in sub-Saharan Africa, especially in rural areas, live in mud huts, often with thatched roofs.

Hanging mosquito nets is very difficult in these homes, and most people prefer the circular nets because they are easier to hang. Although the rectangular nets can be used without a bed, the circular nets cannot, because they have to be tucked under the mattress to fan out. In many African communities, most children younger than five sleep on the floor, so only the rectangular nets would be effective. But the rectangular nets take up quite a bit of room in a mud hut and have to be taken down and rehung every night for the hut to be of use during the day. Given the difficulty of hanging the nets, it is unreasonable to expect people to follow this routine.

A design more suited to the needs of young children would be a net that does not hang at all. One possibility would be a collapsible, tentlike structure, very similar to the crawl-through children’s toys that clutter so many playrooms in the U.S. The challenge would be to make the structure both affordable to produce and durable enough to be used daily for years. In addition to being user-friendly, this free-standing mosquito net would have to be sized for children to ensure that it is used by the intended recipients rather than older, hardier members of the family.

Mosquito nets have been changed before to meet user needs. Several companies have recently introduced nets that are impregnated with long-lasting insecticide, eliminating the need for people to continually apply fresh coatings of chemicals to the nets. Companies must continue to improve mosquito nets if progress is to be made in combating malaria. And once better nets are available, researchers will be able to objectively judge the effectiveness of the distribution programs.

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