The United States is the seventh country with a Ebola patient diagnosed this year, and the only country outside of Africa with a confirmed case.
Ebola has spread quickly since it first turned up in December in rural Guinea. Guinea shares a border with Sierra Leone and Liberia, where the disease next spread. In July, the first case reached Nigeria and, soon after, a the disease was diagnosed in Senegal.
On September 30, the first-ever case was diagnosed in the United States.
There is also an unrelated outbreak of Ebola in the Democratic Republic of the Congo involving a different type of the virus right now.
To learn more, see Vox's 14 facts you should know about the Ebola outbreak.