The frequency of new cases no longer appears to be increasing in Guinea and Liberia but remains high in Sierra Leone, the health agency added.
The Ebola outbreak is thought to have infected more than 14,000 people, almost all of them in West Africa.
The deaths of three more people in Mali have been reported in the past day.
“Transmission remains intense in Guinea, Liberia and Sierra Leone” and the frequency of new cases is still increasing in Sierra Leone, the WHO said in its situation report.
According to our correspondent Imogen Foulkes, the report suggests that the resources needed to contain the virus in Sierra Leone are not in place.
Only 19 of 53 planned treatment centres are operational, while out of the 370 trained burial teams required just 140 have begun work
Health experts have argued that the rate of new cases is more significant that the total death toll, as it reflects how fast the virus is spreading.
More than 2,830 people have died from Ebola in Liberia, with more than 1,100 deaths in both Guinea and Sierra Leone, the WHO said.
Mali has reported four deaths from Ebola, while there were eight reported Ebola deaths in Nigeria, and one in the US.
The total number of deaths has increased by 200 since the WHO’s last situation report on 7 November.
Cumulative deaths up to 11 November
Workers on strike
Also on Wednesday, hundreds of health workers at an Ebola clinic in Sierra Leone went on strike, saying the government had failed to pay them an agreed weekly $100 (£63) “hazard payment”.
The money was due to be paid in addition to salaries the staff receive from medical charity MSF, which runs the Ebola clinic.
The district medical officer says the staff will be paid on Friday for the first two weeks of November, the BBC’s correspondent in Sierra Leone Umaru Fofana reports.
However, the backlog of payments is still being worked out, our correspondent adds.
On Wednesday afternoon, workers’ representative Mohamed Mbawah said they had agreed to send a third of their staff back to the ward to offer minimal assistance “in the interest of the patients who are our people”.
However, he stressed that the strike was still on, and said if the staff were not paid by Friday, “we still stop working completely”.
Meanwhile, the US military said that it expected to send a total of 3,000 troops to Liberia to combat the Ebola outbreak.
The US had initially authorised up to 4,000 troops for the mission in Liberia.
However, Maj Gen Gary Volesky, who is leading the US military mission to fight Ebola in West Africa, told a Pentagon briefing there were a greater-than-expected number of contractors available in Liberia to provide support like construction work.
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