President Obama meets with Emory University doctors and health care workers during his visit Tuesday to the Centers for Disease Control and Prevention in Atlanta. Mandel Ngan/AFP/Getty Images hide caption

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Workers wait to spray disinfectant on medical staff after they treat Ebola patients at a clinic run by Doctors Without Borders, in Monrovia, Liberia. Tommy Trenchard for NPR hide caption

itoggle caption Tommy Trenchard for NPR

Workers with the aid group Doctors Without Borders prepare a new Ebola treatment center near Monrovia, Liberia, on Sunday. The facility has 120 beds, making it the largest Ebola isolation clinic in history. John Moore/Getty Images hide caption

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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

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Medical workers treat Ebola patients at the Eternal Love Winning Africa hospital in Monrovia, Liberia. Three workers at the hospital, including Dr. Kent Brantly (left), have tested positive for Ebola. Courtesy of Samaritan's Purse hide caption

itoggle caption Courtesy of Samaritan's Purse

Dr. Kent Brantly (right) of Samaritan's Purse gives orders to treat Ebola patients through the doorway of the isolation ward in Monrovia, Liberia. Courtesy of Samaritan's Purse hide caption

itoggle caption Courtesy of Samaritan's Purse

Construction workers repair the roof inside the isolation area at the Doctors Without Borders treatment center in Kailahun. Tommy Trenchard for NPR hide caption

itoggle caption Tommy Trenchard for NPR

Government health workers administer blood tests to check for the Ebola virus in Kenema, Sierra Leone, June 25. Reuters/Landov hide caption

itoggle caption Reuters/Landov

Medical workers with the nonprofit Doctors Without Borders treat a patient for Ebola in Gueckedou, Guinea. Despite their protective gear, the workers try to maintain human contact with patients by talking with them and getting close enough to look into their eyes. Sylvain Cherkaoui/Cosmos hide caption

itoggle caption Sylvain Cherkaoui/Cosmos

Lack of awareness about Ebola has fueled the outbreak in West Africa. Here, two Liberian women in Lofa read a pamphlet about how to prevent the spread of the virus. Ahmed Jallanzo/EPA/Landov hide caption

itoggle caption Ahmed Jallanzo/EPA/Landov

On the lookout for SARS, an employee checks a baby's temperature at the Ben Gurion Airport in Israel, in 2003. The deadly virus quickly spread around the world once it reached Hong Kong, a central travel hub. Nir Elias/Reuters/Landov hide caption

itoggle caption Nir Elias/Reuters/Landov