The Ebola outbreak shows no signs of abating, has killed 3,879 people and threatens more Western African nations poorly equipped to deal with the disease, the World Health Organisation has said in a report.

The UN's health authority said on Wednesday that a total of 8,033 people had caught the infection up to October 5, and 3,879 of those had died. Liberia and Sierra Leone, the two worst-hit nations, had less than a quarter of the beds needed.

The news comes as the United States reported that the first patient diagnosed of Ebola in the country has died.

"The situation in Guinea, Liberia, and Sierra Leone continues to deteriorate, with widespread and persistent transmission of Ebola," the organisation said. "There is no evidence that the EVD epidemic in West Africa is being brought under control."

It said a reported fall in the number of new cases in Liberia was "unlikely to be genuine" and rather reflected how responders were being overwhelmed by data.

Meanwhile, Ellen Johnson Sirleaf, Liberia's president, said on Tuesday that international aid to battle the Ebola epidemic was arriving too slowly in her country.

"We just need to see a little bit faster action, that's all. But certainly, in terms of resources both human and financial as well as material, I think the response is well appreciated and is very good. We would like to speed it up," Sirleaf told the Reuters news agency.