Dr. Rick Sacra, who had worked in Liberia in previous years, went back in August to tend to pregnant women and to children. The 51-year-old Massachusetts family physician is the third American to contract the Ebola virus. Courtesy of SIM hide caption

itoggle caption Courtesy of SIM

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