The death toll in the world’s worst-ever Ebola outbreak has shot past 4500, killing at least half of the more than 9000 people infected, fresh World Health Organisation figures show.

In its latest update on Friday, the UN health agency said 4555 people had died from Ebola out of a total of 9216 cases registered in seven countries, as of October 14.

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A toll dated just two days earlier had put the death toll at 4493 out of 8997 cases.

The WHO splits the seven affected countries into two groups, with the first comprised of Guinea, Liberia and Sierra Leone — by far the worst affected nations.

Liberia is the worst-hit of all, with 4262 cases and 2484 deaths, as of October 13.

Sierra Leone meanwhile counted 3410 cases as of October 14, 1200 of whom had died.

Guinea, where the epidemic originated in December, had seen 1519 cases and 862 deaths as of October 14.

The second group counts countries with far fewer cases, including Senegal, which was declared Ebola-free by the WHO on Friday.

That declaration could be made after the benchmark of 42 days passed without any new cases since Senegal’s single, non-fatal Ebola case in August.

There is pressure for the US to take more action against Ebola. Photo: AAP

The second group also counts Nigeria, which has seen 20 cases, including eight deaths, and which looks set to be declared Ebola-free next Monday.

In addition now, the second group includes Spain, where a nurse has been confirmed to have contracted the disease from a missionary she cared for and who died from Ebola after returning from Liberia.

And it counts the United States, where two nurses have fallen ill after caring for a Liberian man, Thomas Eric Duncan, who died on October 8 after becoming the first Ebola case diagnosed in the country.

Health workers continue to pay a heavy price for their efforts with 239 deaths out of 423 cases across the countries.

In the Democratic Republic of Congo, hit by a separate strain of Ebola from the one raging in west Africa, the WHO said there have been 68 cases and 49 deaths up to October 9.