A health worker vaccinates a child during a polio campaign in Bannu, Pakistan, June 25. The Taliban threaten to kill vaccinators and parents who immunize their kids. A Majeed/AFP/Getty Images hide caption

itoggle caption A Majeed/AFP/Getty Images

During nationwide polio campaigns, hundreds of thousands of health workers go door to door, giving children two drops of the polio vaccine. Anadolu Agency/Getty Images hide caption

itoggle caption Anadolu Agency/Getty Images

A health worker gives a child the polio vaccine in Bannu, Pakistan, June 25. More than a quarter-million children in Taliban-controlled areas are likely to miss their immunizations. A. Majeed/AFP/Getty Images hide caption

itoggle caption A. Majeed/AFP/Getty Images

Eerie protective suits and shiny body bags have fueled rumors about the origins of Ebola. Here, a burial team removes the body of a person suspected to have died from the virus in the village of Pendembu, Sierra Leone. Tommy Trenchard for NPR hide caption

itoggle caption Tommy Trenchard for NPR