The head of the United Nations Ebola response mission admits that there were times the U.N. acted "arrogantly" and made mistakes in handling the deadly crisis early on, but said Monday the outbreak will be over in West Africa by August.

Ismail Ould Cheikh Ahmed, who heads the UN team, told the BBC that there was "probably a lack of knowledge and there was a certain degree of arrogance, but I think we are learning lessons."

And even though the U.N. mission has "been running away from giving any specific date, but I am pretty sure myself that it will be gone by the summer."

The virus has killed more than 10,000 people, mostly in Liberia, where 4,283 people have died. Ebola has also claimed 3,712 in Sierra Leone; 2,241 in Guinea; 8 in Nigeria; six in Mali; and one in the United States.

Doctors Without Borders blames the outbreak's horrific spread on a "global coalition of inaction," and says its early calls for help were ignored by the World Health Organization and local governments.

The charity reports that while the number of new patients in Liberia is declining, the numbers are still fluctuating in both Guinea and Sierra Leone, and that a total of 99 new confirmed cases was reported across the three worst-affected countries during the week up to Feb. 22.

It is believed the outbreak began with the death of a toddler in a remote part of Guinea in December 2013, reports the BBC. However, the WHO did not officially announce an outbreak for another three months, and took five months more before it declared a global health emergency. By that time, more than 1,000 people had died.

"We were well aware this was something different in March and April last year and we did try to bring this to the attention of the WHO but also governments within the countries affected," Doctors Without Borders Emergency Coordinator Henry Gray told the BBC.

"And of course it was frustrating that we weren't heard and that has probably led to the scale of the epidemic we see today."

By the end of August, Liberian treatment centers were overwhelmed, and healthcare workers were forced to turn away visibly ill patients, and it wasn't until this January that the WHO admitted during a rare emergency meeting that it had responded too late.

The numbers of Ebola cases are starting to fall, reports Doctors Without Borders, but still, overall cases have not declined much since January, and on Friday, Liberia recorded its first case in more than two weeks ending hopes that the country would soon be declared virus-free.

Cases are rising again in Guinea, and some Sierra Leone patients are not on the lists of known Ebola contacts, so there could be some disease spread that is still going undetected.

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