The WHO said that as of October 8, 4,033 people have died of Ebola out of a total of 8,399 registered cases in seven countries. The last toll put the figures at 3,865 dead from 8,033 cases.

The seven affected countries are split into two groups by WHO.

The first includes Guinea, Liberia and Sierra Leone - by far the worst-affected countries.

The second group consists of Nigeria, Senegal, Spain and US, which have seen a small number of highly isolated cases.

Liberia is the worst-hit of all, with 4,076 cases and 2,316 deaths, followed by Sierra Leone with 2,950 cases and 930 deaths. Guinea, where the epidemic originated in December, has seen 1,350 cases and 778 deaths.

Health workers continue to pay a heavy price for their efforts, with 233 deaths out of 416 cases across the countries.

Nigeria has now been declared Ebola-free and its toll remains unchanged at eight dead from 20 cases.

There has been one death in the US and one case contracted in Spain.

The toll remains unchanged in Senegal with one case. In the Democratic Republic of Congo, hit by a separate strain of Ebola from the one raging in West Africa, WHO says there have been 71 cases and 43 deaths up to October 7.

The UN special envoy on Ebola said on Friday that the number of cases was probably doubling every three-to-four weeks and the response needed to be 20 times greater than it was at the beginning of October.