Despite its proven benefits, current ITN use in sub-Saharan Africa also is low. Most households in malaria endemic areas do not possess any net, insecticide-treated or not. In nine African countries surveyed between 1997 and 2001, a median 13 percent of households had one or more nets of any kind; a median 1.3 percent of households in three countries owned at least one ITN; and across 28 countries, only 15 percent of children under age 5 were sleeping under any net (WHO/UNICEF, 2003). Not surprisingly, net ownership and use are lowest in poor households.
In addition to purchase cost and re-treatment, one additional barrier to ITN use is the common misconception that ITNs are meant to control mosquitoes as opposed to malaria. In urban areas with untreated wastewater and high year-round populations of “nuisance” culicine mosquitoes, this misconception favors ITN use. In rural areas, however, mosquito densities and mosquito nuisance are generally lower despite year-round biting by clandestine female anophelines. As a result, ITN use is rarely sustained night after night, especially during the dry season (Gyapong et al., 1996; Binka et al., 1996; Binka and Adongo, 1997).
In western Kenya, the use of ITNs was observed directly in nearly 800 households (Alaii et al., 2003a). About 30 percent of ITNs in homes were unused. Children less than 5 years of age were less likely to use ITNs than older individuals, and ITNs were more likely to be used in cooler weather. Neither mosquito numbers, relative wealth, number of house occupants, nor educational level of the head of the household influenced adherence. Excessive heat was often cited as a reason for not using a child’s ITN. Researchers also commented on the effort required of caregivers to store and rehang the ITN on a daily basis (Alaii et al., 2003a).
Finally, misunderstandings about malaria also lower incentives to use ITNs and/or IRS. In southern Ghana, the Adangbe people believe that asra, a local disease that resembles malaria, is the result of prolonged exposure to heat (Agyepong, 1992). In Bagamoyo District, Tanzania, degedege—a local term for fever and convulsions—is often blamed on a bird-spirit instead of cerebral malaria (Makemba et al., 1996). In western Kenya, many ITN trial participants believed that malaria was a multicausal disease and that ITNs were therefore only partly effective (Alaii et al., 2003b).
In areas of high malaria transmission, prevalence of infection may vary significantly over relatively short distances. This has been observed not only in Africa (Greenwood, 1999) but in other countries, such as Papua New