A micrograph shows red blood cells infected by the malaria parasite Plasmodium falciparum. John C. Tan/AP hide caption

itoggle caption John C. Tan/AP

Chhay Meth, 9, suffering through an attack of malaria at the family's home in O'treng village on the outskirts of Pailin, Cambodia, in 2009. A drug-resistant form of malaria in the region medical led officials to declare a health emergency. David Longstreath/AP hide caption

itoggle caption David Longstreath/AP

A mother held her baby as she received an experimental malaria vaccine at the Walter Reed Project Research Center in Kombewa in Western Kenya in Oct. 2009.

Karel Prinsloo/AP hide caption

itoggle caption Karel Prinsloo/AP

Women hold mosquito nets after receiving them at a distribution point in Sesheke, Zambia. Researchers say malaria may have rebounded in some parts of Zambia and Senegal because of resistance to the insecticide-treated nets. ASSOCIATED PRESS hide caption

itoggle caption ASSOCIATED PRESS