Dr. Margaret Chan, director-general of the World Health Organization, has said of Ebola: "It overwhelmed the capacity of WHO, and it is a crisis that cannot be solved by a single agency or single country." Fabrice Coffrini/AFP/Getty Images hide caption

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Ebola was out of control in Liberia in August, when this picture was taken. Dominique Faget/AFP/Getty Images hide caption

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Health workers rest outside a quarantine zone at a Red Cross facility in the town of Koidu, Kono district in Eastern Sierra Leone on Friday. The World Health Organization says the number of Ebola deaths in the current outbreak has exceeded 7,000. Baz Ratner/Reuters/Landov hide caption

itoggle caption Baz Ratner/Reuters/Landov

Community workers build an Ebola clinic on Nov. 8 in Lokomasama, near Port Loko, Sierra Leone. The community decided to organize and fight the disease — building a holding center for suspected cases, enforcing a travel ban. It created a $100 fine for a handshake and a $200 fine plus six months in jail for an illegal burial. Francisco Leong/AFP/Getty Images hide caption

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Among the dilemmas that arise when health workers are in their protective garb: What if you can't find the person assigned to be your Ebola Treatment Unit partner? John W. Poole/NPR hide caption

itoggle caption John W. Poole/NPR

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

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A licensed clinician is decontaminated before disrobing at the end of a simulated training session by CDC in Anniston, Ala. Training can take a several weeks, making some employers reluctant to encourage their medical workers to volunteer in the Ebola outbreak. Brynn Anderson/AP hide caption

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Adrian Hill, director of the Jenner Institute and chief investigator of the trials with an Ebola vaccine his organization developed, holds a vial of the vaccine. Steve Parsons/WPA Pool/Getty Images hide caption

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A World Health Organization worker trains nurses how to use Ebola protective gear in Freetown, Sierra Leone. Michael Duff/AP 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

Protective equipment is in short supply. Here, a Liberian burial team carefully disinfects its gloves before disposing of them. John Moore/Getty Images hide caption

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A health worker cleans his hands with chlorinated water before entering an Ebola screening tent at the Kenema Government Hospital in Sierra Leone. More than 300 Sierra Leoneans have died of the disease. Michael Duff/AP hide caption

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A man lies in a newly opened Ebola isolation center in a closed school in Monrovia, Liberia, on Thursday. The official death toll of 1,000 people in four countries is likely below the actual number, the World Health Organization says. John Moore/Getty Images hide caption

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