GENEVA (AP) — The total number of deaths attributed to the Ebola outbreak in West Africa has risen above 4,000, the World Health Organization said Friday.

The Geneva-based U.N. agency said that 4,033 deaths confirmed, probably or suspected to have been caused by Ebola have now been recorded.

The vast majority of them were in the three worst-affected countries, Liberia, Sierra Leone and Guinea.

As of the end of Wednesday, a total of 8,399 confirmed, probable and suspected cases of Ebola had been reported from seven countries, WHO said. The three worst-affected countries accounted for 8,376 cases.

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."

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