The U.S. Ebola case: 5 things to know

• When, how it happened: Health officials don’t know how the man was infected, but he flew from Liberia on Sept. 19 and arrived to visit relatives in the U.S. a day later. His symptoms started about Sept. 24; he sought medical care on Sept. 26 and was admitted to the hospital Sept. 28.

• Risk to fellow travelers: The CDC said Ebola doesn’t spread until someone gets sick, and he didn’t get sick until four days after getting off the plane, so officials are not seeking passengers. The virus does not spread through the air – only through close contact with bodily fluids from a sick person.

• Risk to people of Dallas: Several family members and maybe a few community people are being monitored for possible risk, the CDC said.

• How long risk lasts: People are watched for fever or other possible signs for 21 days.

• If you think you are at risk: Contact the CDC.