The outbreak is the second largest in history after the one in West Africa in 2014 and 2015, which caused 28,616 cases and 11,310 deaths.

People in the affected communities have sometimes rejected or avoided treatment or vaccination, out of unfamiliarity with the disease, distrust of foreign health workers and even fear that outsiders have brought the disease.

There is also resentment over all the attention given to Ebola when the impoverished region has other severe health problems, like a measles outbreak that has killed 2,000 children, as well as cholera outbreaks, endemic malaria and high rates of women dying from childbirth.

Dr. Tedros said people in the street in Congo have asked him, “‘Are you here to help us, or to prevent this thing from coming to you? Are you doing this for us, or for yourself?’ It embarrasses me.”

He said people in the region needed to be reassured that the international assistance would stay long after Ebola was gone.

“We should not appear to be seen as if we are parachuting in and out because of Ebola,” he said.

Speakers at the U.N. meeting on Monday said there was an urgent need for more money from member countries to fight the outbreak. If nations do not open their coffers now, the situation will only spiral further out of control and cost far more in the long run, warned Mark Lowcock, the U.N. under-secretary-general for humanitarian affairs and emergency relief coordinator. He said that $2 billion had been spent on the West African outbreak.

So far, more than 161,000 people have been vaccinated, with a Merck vaccine that is considered highly effective. Other companies have also produced Ebola vaccines, and health experts had hoped to deploy those as well, but Congo’s health ministry has said it will use only Merck’s vaccine, because it has taken tremendous efforts to gain the community’s acceptance of that one.