Ron Klain, a Democratic lawyer and President Barack Obama's choice to lead the government's response to the Ebola outbreak, is leaving the White House Thursday after nearly four months on the job. He will return to the private sector.

In a statement today, the president commended Klain's "dedicated and tireless" work.

"The results of that effort speak for themselves, so much so that we can now turn our focus to our ultimate goal of getting to zero cases in West Africa, which might have seemed unthinkable last fall," the president said.

Though the number of new Ebola cases in West Africa has risen in recent weeks, the infection rate has slowed dramatically since September, according to the World Health Organization. Ebola killed more than 9,000 people in West Africa over the last year. Of the four people in the U.S. with confirmed cases of Ebola, one died.

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The U.S. sent nearly 3,000 troops to Liberia to train local health workers, transport medical supplies and set up Ebola treatment units. Wednesday, President Obama said that mission would wind down, but the administration will continue its vigilance. "As long as there is even one case of Ebola that's active out there, risks still exist. Every case is an ember that, if not contained, can light a new fire. So we're shifting our focus from fighting the epidemic to now extinguishing it," the president said.