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Health officials keep saying that the smartest way to keep Americans safe from Ebola is to stop the outbreak at its epicenter in West Africa. And in West Africa, the virus is still raging.

The number of cases in the three hardest-hit countries, Guinea, Liberia and Sierra Leone, just sped past 10,000. The number of deaths will almost certainly pass 5,000 the next time world health officials update their count.

Senegal and Nigeria have been declared Ebola-free, but Mali reported its first case last week. And in an alarming twist, a U.N. official says the data in West Africa is so bad that authorities don’t know how fast the virus is spreading or where the worst spots are for new cases.

While the news at home is good — with the release of a Dallas nurse on Tuesday, only one Ebola patient is hospitalized in the United States — leaders in the hot zone stress that the world must not slow its response there.

“Together, we can make sure that the world is safe,” Liberian President Ellen Johnson Sirleaf, whose country has been hardest-hit, told NBC News. “Because if not, and this disease spreads, then we’re all in trouble.”

She said it was an “overreaction” for some U.S. states to order mandatory quarantines for health care workers returning from Ebola-stricken countries. Health officials in the United States have said those quarantines could discourage health workers from going to help.

“We understand the fears,” Sirleaf said. “There’s fear even in our own society. But we think that fear can be overcome with the right messaging from leaders.”

Sirleaf stressed progress in her country, including the building of 17 special Ebola treatment units and the outfitting of 600 community care centers to handle contacts of Ebola patients who show up sick.

But the situation in Liberia remains dire by any measure. The British medical journal Lancet Infectious Diseases reported this week that Ebola could kill 90,000 people in Liberia alone by mid-December if the world doesn’t accelerate its response.

Alison Galvani, an author of the report and a professor of epidemiology at Yale, cited a “rapidly closing window of opportunity for controlling the outbreak and averting a catastrophic toll of new Ebola cases and deaths in the coming months.”

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And in a troubling development on Tuesday, Anthony Banbury, the top U.N. official working on Ebola in West Africa told The Associated Press that health officials don’t even have reliable case information from some of the hardest-hit areas.

“We don’t know exactly what is happening,” he said.

A CDC report in September said that 1.4 million people could contract Ebola in the three countries by January without an accelerated public health response.

Since then, Western countries have committed more help. The United States has pledged more than $340 million, and international aid organizations now have hundreds of people on the ground.

But there’s a long way to go. Banbury said West Africa still needs three things above all — people, supplies and money, and especially people.

In Sierra Leone, Guinea and Liberia alone, 5,000 more health workers are needed to fight the epidemic, Jim Yong Kim, the president of the World Bank, said Tuesday. He said he is worried about where they can be found, with Ebola fear so high.

Doctors in the United States have expressed a related concern this week as they have lined up to criticize governors who have ordered quarantines for health workers returning from Ebola concerns.

Adding a hardship for the health workers, not to mention the risk of increased public stigma, will make them less likely to volunteer for duty, the New England Journal of Medicine and others argued.

Liberia is the hardest-hit of the three countries in the hot zone, with more than 4,600 cases and more than 2,700 deaths — more than half the world’s Ebola dead. An additional 7,000 people are being watched for symptoms, Sirleaf said.

The government in August ordered cremation for anyone killed by Ebola in the capital, Monrovia. That order has been blamed for accelerating the outbreak, keeping Liberians away from doctors because they want to be buried instead.

Samantha Power, the U.S. ambassador to the United Nations, is touring the Ebola-stricken countries this week and pointed out on Twitter that nobody even hugs in Guinea anymore.

President Barack Obama, while praising the progress on the handful of U.S. cases, sought to shift the focus back to West Africa on Tuesday. He said the United States can’t shy away from the heart of the epidemic.

“If we don’t have a robust international response in West Africa, then we are actually endangering ourselves here back home,” he said.

The president said health workers volunteering for duty in West Africa should be praised and encouraged.

“We want to make sure that we understand that they are doing God’s work over there,” he said, “and they’re doing that to keep us safe.”

The Associated Press and Reuters contributed to this report.