Ebola: New York doctor's case explained
A New York doctor who recently returned from Ebola-hit Guinea in West Africa has tested positive for the disease.
Dr Craig Spencer, who treated Ebola patients while working for the charity Medecins Sans Frontieres, came down with a fever on Thursday, days after his return.
He is the first Ebola case diagnosed in New York, and the fourth in the US.
It has prompted questions about how, despite all the checks, someone with the virus could have slipped through the net.