"The clock is ticking, and Ebola is winning," Liu warned. "The time for meetings and planning is over. It is now time to act. Every day of inaction means more deaths and the slow collapse of societies."

British patient gets better

Medical personnel have been particularly vulnerable in this Ebola outbreak.

William Pooley, a British volunteer nurse who cared for Ebola patients in Sierra Leone, was the first Briton known to be infected.

Doctors flew him back to be treated in an isolation unit at the Royal Free Hospital in North London. He stayed there for 10 days of treatment that included the experimental drug ZMapp, which was also used to treat two American medical personnel last month who have since been released from the hospital.

Pooley's doctors released him from care on Tuesday.