Worst Ebola outbreak in history: What you need to know

The virus exploded in neighboring Sierra Leone, where hundreds of deaths can be traced to the funeral of a widely respected traditional healer who died of Ebola after people came from Guinea seeking treatment from her. (The World Health Organization does not know her name.)

International organizations including the United Nations, Medecins Sans Frontieres and the World Health Organization have raced to fight the outbreak.

CNN