A security man takes visitors' temperatures Wednesday at the Transcorp Hilton hotel in Abuja, Nigeria, about 400 miles north of Port Harcourt. Afolabi Sotunde/Reuters/Landov hide caption

itoggle caption Afolabi Sotunde/Reuters/Landov

Kenyan health officials take the temperatures of passengers arriving at the Nairobi airport on Thursday. Kenya has no reported cases of Ebola, but it's a transportation hub and so is on alert. Simon Maina/AFP/Getty Images hide caption

itoggle caption Simon Maina/AFP/Getty Images

Average life expectancy around the world has ticked up over the past twenty years. Here it's shown for men in 2009. The extremes are in dark green and dark red, which represent 78 to 82 years old and less than 66 years old, respectively. Courtesy of the Institute for Health Metrics and Evaluation hide caption

itoggle caption Courtesy of the Institute for Health Metrics and Evaluation