Chapter 002. Global Issues in Medicine (Part 7) Malaria We turn now to the world's third largest infectious killer, which has taken its greatest toll among children, especially African children, living in poverty. The Cost of Malaria Malaria's human toll is enormous. An estimated 250 million people suffer from malarial disease each year, and the disease annually kills between 1 million and 2.5 million people, mostly pregnant women and children under the age of 5. The poor disproportionately suffer the consequences of malaria: 58% of malaria deaths occur in the poorest 20% of the world's population, and 90% are registered in sub-Saharan Africa. The differential magnitude of this mortality burden is greater than that associated with any other disease. Likewise, the morbidity differential is greater for malaria than for diseases caused by other pathogens, as documented in a study from Zambia that revealed a 40% greater prevalence of parasitemia among children under 5 in the poorest quintile than in the richest. Despite suffering the greatest consequences of malaria, the poor are precisely those least able to access effective prevention and treatment tools. Economists describe the complex interactions between malaria and poverty from an opposite but complementary perspective: they delineate ways in which malaria arrests economic development both for individuals and for whole nations. Microeconomic analyses focusing on direct and indirect costs estimate that malaria may consume up to 10% of a household's annual income. A Ghanaian study that categorized the population by income group highlighted the regressive nature of this cost: the burden of malaria represents only 1% of a wealthy family's income but 34% of a poor household's income. At the national level, macroeconomic analyses estimate that malaria may reduce the per capita gross national product of a disease-endemic country by 50% relative to that of a nonmalarial country. The causes of this drag include high fertility rates, impaired cognitive development of children, decreased schooling, decreased saving, decreased foreign investment, and restriction of worker mobility. Given this enormous cost, it is little wonder that an important review by the economists Sachs and Malaney concludes that "where malaria prospers most, human societies have prospered least." Rolling Back Malaria In part because of differences in vector distribution and climate, resource- rich countries offer few blueprints for malaria control and treatment that are applicable in tropical (and resource-poor) settings. In 2001, African heads of state endorsed the WHO Roll Back Malaria (RBM) campaign, which prescribes strategies appropriate for sub-Saharan African countries. RBM recommends a three-pronged strategy to reduce malaria-related morbidity and mortality: the use of insecticide-treated bed nets (ITNs), combination antimalarial therapy, and indoor residual spraying. ITNs are an efficacious and cost-effective public health intervention. A meta-analysis of controlled trials indicates that malaria incidence is reduced by 50% among persons who sleep under ITNs compared with that among those who do not use nets at all. Even untreated nets reduce malaria incidence by one-quarter. On an individual level, the utility of ITNs extends beyond protection from malaria. Several studies suggest that all-cause mortality is reduced among children under 5 to a greater degree than can be attributed to the reduction in malarial disease alone. Morbidity (specifically that due to anemia) predisposing children to diarrheal and respiratory illnesses and pregnant women to the delivery of low- birth-weight infants is also reduced in populations using ITNs. In some areas, ITNs offer a supplemental benefit by preventing transmission of lymphatic filariasis, cutaneous leishmaniasis, Chagas' disease, and tick-borne relapsing fever. At the community level, investigators suggest that the use of an ITN in just one household may reduce the number of mosquito bites in households up to several hundred meters away. The cost of ITNs per DALY saved is estimated at $10–$38 (U.S.), which qualifies ITNs as a "very efficient use of resources and [a] good candidate for public subsidy." 1 Some RBM programs have had limited success, but overall the burden of malarial disease has continued to grow. In fact, annual malaria-attributable mortality increased between 1999 and 2003. While the RBM campaign's own report from that year is quick to note that morbidity and mortality data-collection methods in sub-Saharan Africa are inadequate and indicators may thus lag behind actual outcomes of ongoing campaigns, they nevertheless acknowledge that "RBM is acting against a background of increasing malaria burden." . Chapter 002. Global Issues in Medicine (Part 7) Malaria We turn now to the world's third largest infectious killer, which has taken its greatest. data-collection methods in sub-Saharan Africa are inadequate and indicators may thus lag behind actual outcomes of ongoing campaigns, they nevertheless acknowledge that "RBM is acting against a background. Rolling Back Malaria In part because of differences in vector distribution and climate, resource- rich countries offer few blueprints for malaria control and treatment that are applicable in