When a high-risk patient is evacuated, strict precautions are followed. Above, aid workers and doctors in protective gear transfer Manuel Garcia Viejo, a Spanish priest diagnosed with Ebola, to a waiting ambulance at a Madrid airport. Spanish Defense Ministry/AP hide caption

itoggle caption Spanish Defense Ministry/AP

The entrance to the emergency room at Texas Health Presbyterian Hospital Dallas, where Thomas Eric Duncan was treated before he died from Ebola a week ago. Two health care workers who treated Duncan have tested positive for the disease. LM Otero/AP hide caption

itoggle caption LM Otero/AP

A plane arrives at New York's John F. Kennedy International Airport. Since Ebola screenings began Saturday, none of the 91 passengers identified as having an increased risk of an Ebola infection was found to be sick, the CDC says. Spencer Platt/Getty Images hide caption

itoggle caption Spencer Platt/Getty Images

Passengers from three West African countries will face screening for Ebola symptoms when they arrive at John F. Kennedy International Airport in New York. Travelers are seen here at a JFK checkpoint earlier this week. Four other airports will begin screening next week. JUSTIN LANE/EPA /LANDOV hide caption

itoggle caption JUSTIN LANE/EPA /LANDOV

Dallas County Judge Clay Jenkins, right, escorts people who were at the apartment unit where Thomas Eric Duncan, a Liberian citizen diagnosed with the Ebola virus, had been staying. Jenkins used his car to drive the people to a new place to stay in Dallas. JIM YOUNG/Reuters /Landov hide caption

itoggle caption JIM YOUNG/Reuters /Landov

Surrendered handguns are piled in a bin during a gun buyback event in Los Angeles on May 31, 2014. David McNew/Getty Images hide caption

itoggle caption David McNew/Getty Images

President Obama spoke Tuesday about the U.S. plan to fight the Ebola epidemic in West Africa, speaking at the Centers for Disease Control and Prevention. The White House plan reportedly includes deploying 3,000 U.S. military personnel and training health care providers in Liberia. Mandel Ngan/AFP/Getty Images hide caption

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Shops are closed in Monrovia's West Point neighborhood as part of a quarantine to contain the spread of Ebola. Zoom Dosso/AFP/Getty Images hide caption

itoggle caption Zoom Dosso/AFP/Getty Images

Ebola virus survivor Dr. Kent Brantly (center) and his wife, Amber (left), walk at a news conference at Emory University Hospital in Atlanta Thursday. Brantly and aid worker Nancy Writebol were discharged from the hospital less than a month after they contracted Ebola while treating patients in Liberia. Erik S. Lesser/EPA/LANDOV hide caption

itoggle caption Erik S. Lesser/EPA/LANDOV

Police officers guard an entrance to Emory University Hospital after an ambulance arrived transporting an American that was infected with the Ebola virus on Saturday. A specially outfitted plane carrying Dr. Kent Brantly from West Africa transpoted him to a military base in Georgia. Another American with Ebola is expected to join him at the hospital in a few days. David Goldman/AP hide caption

itoggle caption David Goldman/AP

In 1995, amid an Ebola outbreak, Zairian Red Cross personnel picked up sick people and bodies left on the streets of Kikwit, 250 miles from the capital Kinshasa. Jean-Marc Bouju/AP hide caption

itoggle caption Jean-Marc Bouju/AP

Red Cross volunteers prepare to bury the body of an Ebola victim in Pendembu, Sierra Leone, early this month. Tommy Trenchard for NPR hide caption

itoggle caption Tommy Trenchard for NPR

The CDC's director, Tom Frieden, testified before a congressional subcommittee Wednesday regarding a recent anthrax incident and lab safety improvements he is instituting. AFP/Getty Images hide caption

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Particles of H5N1 virus — a particularly dangerous type of bird flu that can infect people — attack lung cells. Chris Bjornberg/Science Source hide caption

itoggle caption Chris Bjornberg/Science Source

Sick with chikungunya, Karla Sepulveda, 5, waits in a public hospital with her grandmother in Boca Chica, Dominican Republic, on May 15. The Caribbean nation has reported more than 100,000 cases this year. Ezequiel Abiu Lopez/AP hide caption

itoggle caption Ezequiel Abiu Lopez/AP

Deaths from oxycodone overdoses fell sharply in Florida after the state cracked down on pain clinics and implemented dispensing restrictions. Robin Nelson/Zumapress/Corbis hide caption

itoggle caption Robin Nelson/Zumapress/Corbis