Children under 5 years of age in sub-Saharan Africa also suffer the majority of the annual 350 million infections and 500,000 deaths globally. Reducing this burden is a global public health priority, particularly in areas of high transmission like Western Kenya. In the absence of an effective vaccine, global malaria control requires effective treatments and a suite of preventive measures that act upon the parasite, environment, and host. Among these preventive strategies is the administration of prophylactic antimalarials to high risk groups, including pregnant women, infants, and children exposed to seasonal malaria transmission. In these high-risk groups malaria morbidity is substantially reduced by routine periodic intake of effective antimalarials.