The Geneva-based WHO said 10,141 people have been diagnosed with the deadly virus, an increase from its previous estimate of about 9000 cases.
It added that 4922 people have died from the virus, which has hit Guinea, Liberia and Sierra Leone the hardest.
The UN organisation said that no new cases or deaths linked to the virus had been recorded in Liberia in the last three days.
In Sierra Leone, almost 200 new cases were reported, bringing the total number of infections to 3896.
Twenty-two people died of the disease in the last three days, WHO said.
Although the worst Ebola outbreak has been largely limited to west Africa, there have also been confirmed cases in the United States, Spain and Mali.
About half of those infected with the disease die.
Mali
Mali authorities are scrambling to calm fears after Ebola claimed its first victim in the African country,
a contagious toddler who took a 1000-kilometre bus journey before being treated.
Mali President Ibrahim Boubacar Keita aimed to ease fears after the death of a two-year-old girl, the first Ebola case in the landlocked country, who travelled from neighbouring Guinea.
"We are doing everything to prevent panic and psychosis," he said in an interview with French radio.
"Since the start of this epidemic, we in Mali took all measures to be safe, but we can never hermetically seal ourselves from this," he said.
"Guinea is a neighbouring country, we have a common border that we have not closed and that we will not close."
Mauritania meanwhile reinforced controls on its border with Mali, which led to a de facto closing of the border, according to local sources.
The WHO said it was treating the situation in Mali as an "emergency" because the toddler had travelled for hundreds of kilometres on public transport with her grandmother while showing symptoms of the disease - meaning that she was contagious.
The girl and her grandmother travelled by public transport from Keweni in Guinea through the towns of Kankan, Sigouri and Kouremale to the Malian capital, Bamako.
The route made for a journey of around 1000 kilometres.
Mali's health ministry however denied that the girl had been showing symptoms before she reached Kayes.
One metric ton of medical supplies was dispatched from WHO stocks in Liberia to Bamako late on Friday.
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