UN envoy: Ebola cases doubling every 3-4 weeks

The U.N. special envoy on Ebola says the number of cases is probably doubling every three-to-four weeks and the response needs to be 20 times greater than it was at the beginning of October.

David Nabarro warned the U.N. General Assembly on Friday that without the mass mobilization of the world to support the affected countries in West Africa, "it will be impossible to get this disease quickly under control, and the world will have to live with the Ebola virus forever."

Nabarro said the U.N. knows what needs to be done to catch up to and overtake Ebola's rapid advance "and together we're going to do it."

"And our commitment to all of you is to achieve it within a matter of months—a few months," he said.