The third American health worker to contract the Ebola virus in Liberia was an obstetrician at the ELWA hospital, which is run by the missionary group SIM. Ahmed Jallanzo/EPA/Landov hide caption

itoggle caption Ahmed Jallanzo/EPA/Landov

Gravel helps keep the floor level and prevents moisture from seeping up. The floor installers are Jean Pierre (left), a mason, and Daniel Shenyi, operations manager for EarthEnable. Courtesy of EarthEnable hide caption

itoggle caption Courtesy of EarthEnable

Kwei Quartey sets one of the crime scenes in his second D.I. Dawson book in Agbogbloshie, an Accra slum. Ofeibea Quist-Arcton /NPR hide caption

itoggle caption Ofeibea Quist-Arcton /NPR

Barbara Bush helps a nun to fit on a hearing device during a 2012 event in Gulu, Uganda. She says was interested in architecture as a college student but became a global health activist after visiting East Africa with her parents. Reuters/Landov hide caption

itoggle caption Reuters/Landov

A member of the Lesotho military looks on as he stands guard in front of an armed personnel carrier at the entrance of the army barracks in the capital Maseru on Saturday. Lesotho's Prime Minister Thomas Thabane has accused the army of staging a coup. Siphiwe Sibeko/Reuters/Landov hide caption

itoggle caption Siphiwe Sibeko/Reuters/Landov

Peter Piot was one of the co-discoverers of the Ebola virus in 1976. "I never thought we would see such a devastating and vast epidemic," he says. Leon Neal/AFP/Getty Images hide caption

itoggle caption Leon Neal/AFP/Getty Images