"There's still a significant gap between where we are and where we need to be" in regard to a response to the Ebola epidemic, President Obama told world leaders at the United Nations on Thursday. (AP)

— President Obama warned a summit of world leaders Thursday that the Ebola outbreak that has infected thousands in west Africa has gone beyond a health crises and is a “growing threat to regional and global security.”

Citing new commitments from the United Nations last week, Obama said there had been progress. But after meeting with leaders from African nations at the U.N. General Assembly, the president cautioned that “we need to be honest with ourselves. It’s not enough.”

“There’s still a significant gap between where we are and where we need to be,” he said.

Obama’s call to action on Ebola comes amid new estimates that the virus could potentially infect 1.4 million people in Liberia and Sierra Leone by the end of January, according to a statistical forecast by the U.S. Centers for Disease Control and Prevention published Tuesday.

A report in the New England Journal of Medicine warned that the epidemic might never be fully controlled and that the virus could become endemic, crippling civic life in the affected countries and presenting an ongoing threat of spreading elsewhere.

Thousands of U.S. troops are being dispatched to West Africa to lead the fight against Ebola, in addition to the $175 million already spent. But what is the rest of the world doing? Here are some of the publicly announced plans from other nations. (Adam Taylor and Tom LeGro/The Washington Post)

“Stopping Ebola is a priority for the United States,” Obama said Thursday. “We will continue to lead and do our part. But this must also be a priority for the world.”

Obama emphasized that the United States would prioritize the fight against the disease but “we cannot do it alone.” He said a coordinated international response could be the difference between 10,000 or 20,000 deaths and hundreds of thousands of deaths.

Last week, Obama announced that the U.S. military will take the lead in overseeing what has been a chaotic and widely criticized response to the worst Ebola outbreak in history, dispatching up to 3,000 military personnel to West Africa in an effort that could cost up to $750 million over the next six months.

On Friday, the White House will host 44 nations in a global health security summit.

The World Bank on Thursday said it would contribute $170 million in new emergency funding to combat the virus, bringing its total commitments to $400 million.

But aid workers continue to warn that the international community is not moving fast enough. On Thursday, Joanne Liu, president of Doctors Without Borders, was set to appear at the U.N. conference and planned to tell the delegates that “the promised surge has not yet delivered,” according to her prepared remarks.

“Pledges of aid and unprecedented U.N. resolutions are very welcome. But they will mean little, unless they are translated into immediate action,” she planned to say. “Fear and panic have set in, as infection rates double every three weeks. Mounting numbers are dying of other diseases, like malaria, because health systems have collapsed. . . . Today, Ebola is winning.”

As the worst Ebola outbreak in history unfolds in West Africa, The Post's Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)

Also Thursday, Secretary of State John F. Kerry announced he has appointed Nancy Powell to be the “Ebola coordinator” for the State Department.

Powell, who resigned as ambassador to India in March, will lead the Ebola Coordination Unit, State Department spokeswoman Jen Psaki said in a statement.

In her new role, Psaki said, Powell “will lead the State Department’s outreach to international partners, including foreign governments, to ensure a speedy and truly global response to this crisis.”

Juliet Eilperin, J. Freedom du Lac and Lena H. Sun contributed to this report.