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

A health worker from Doctors Without Borders examines Ebola patient Finda Marie Kamano, 33, at her home in Conakry, Guinea, in April. The outbreak that began in February is still spreading in West Africa. Sylvain Cherkaoui/Cosmos/Courtesy of Doctors Without Borders hide caption

itoggle caption Sylvain Cherkaoui/Cosmos/Courtesy of Doctors Without Borders

In this colored transmission electron micrograph, an infected cell (reddish brown) releases a single Ebola virus (the blue hook). As it exits, the virus takes along part of the host cell's membrane (pink, center), too. That deters the host's immune defenses from recognizing the virus as foreign. London School of Hygiene & Tropical Medicine/Science Source hide caption

itoggle caption London School of Hygiene & Tropical Medicine/Science Source

Testing for Ebola, a scientist in a mobile lab at Gueckedou, Guinea, separates blood cells from plasma cells to isolate the virus's genetic sequence. Misha Hussain/Reuters /Landov hide caption

itoggle caption Misha Hussain/Reuters /Landov

Rose Komano, 18 and the mother of three, was the first Ebola patient to overcome the virus in southeastern Guinea, the epicenter of the outbreak. On April 3, she posed at a health clinic in the Gueckedou region. Misha Hussain /Reuters /Landov hide caption

itoggle caption Misha Hussain /Reuters /Landov

The new normal in Guinea is washing hands with a mixture of water and bleach--shown here at the border entrance of Buruntuma, in the Gabu area on Tuesday. Tiago Petinga/EPA /LANDOV hide caption

itoggle caption Tiago Petinga/EPA /LANDOV

A nurse of the 'Doctors without Borders' medical aid organisation examines a patient in the in-take area at a center for victims of the Ebola virus in Guekedou, on April 1, 2014. The viral haemorrhagic fever epidemic raging in Guinea is caused by several viruses which have similar symptoms — the deadliest and most feared of which is Ebola. Seyllou/AFP/Getty Images hide caption

itoggle caption Seyllou/AFP/Getty Images

The fatality rate in an Ebola outbreak ranges from 25 percent to 90 percent, depending on the particular strain of the virus involved. Cynthia Goldsmith/ Centers for Disease Control and Prevention hide caption

itoggle caption Cynthia Goldsmith/ Centers for Disease Control and Prevention