The rate of new Ebola infections here has declined so sharply in recent weeks that even some of the busiest treatment facilities are now only half-full and officials are reassessing the scale of the response needed to quell the epidemic.

The turnaround has occurred without the provision of a single treatment bed by the U.S. military, which has promised to build 17 Ebola facilities containing 100 beds each across Liberia. Those treatment units will be constructed, said Bill Berger, head of the U.S. Agency for International Development’s Disaster Assistance Response Team here. But the option of initially opening some with as few as 10 beds is “being discussed,” he said.

That would provide people in all parts of the country access to a nearby treatment unit should they become infected in the months to come. And each facility would be constructed so that it could be quickly expanded to as many as 100 beds if the need arises, he said. The United States has spent $360 million so far fighting Ebola in West Africa.

No one tracking the outbreak is close to declaring the deadly hemorrhagic disease vanquished, and all are wary that the virus, which has receded at times over the past seven months, could suddenly flare again in this impoverished country, the epicenter of the West African Ebola catastrophe.

But five days after the World Health Organization said new infections were declining in Liberia, a 157-bed treatment center in the city of Foya, where the epidemic began seven months ago, held no patients Monday, according to a nurse there. The same facility received no new admissions last Wednesday, the most recent day for which government statistics were available.

In Liberia, reports of new Ebola cases have tapered off.

Here in the hard-hit capital, Island Clinic — whose official capacity is 150 and which housed 215 Ebola patients on its worst day in September — had 89 patients Sunday, according to its director, Attai Omorutu. At ELWA 3, the Doctors Without Borders facility that has scaled up to handle 250 people, 65 beds were occupied Monday.

Only at ELWA 2, the last of the city’s three open treatment centers, was there anything close to a full house: 64 patients in a facility that can handle about 80 and where an expansion is underway.

“I will be home for Christmas,” said Omorutu, who lives in Uganda. “And there will be no Ebola here for Christmas.”

Most experts are not as optimistic as Omorutu, and some worry that this is just the latest temporary lull in the worst Ebola outbreak on record. Since the start of the outbreak late last year, the virus has infected 13,567 people in eight countries, killing 4,951 of them, with the vast majority of cases occurring in Liberia, Sierra Leone and Guinea.

Nevertheless, just about everyone here acknowledges that current conditions are a welcome improvement from the devastating height of the epidemic just over a month ago.

At that time, critically ill Ebola victims lay outside the gates of overwhelmed treatment centers, unable to gain entry. Corpses were routinely collected from roadsides and homes. Body-retrieval teams and the city’s tiny ambulance corps had no hope of keeping up with calls for their services. The World Health Organization predicted the possibility of 10,000 new cases a week in the region by early December.

No longer. Now, a state-of-the-art treatment center set to open soon on Monrovia’s main road is expected to see few patients, at least in the immediate future.

“It’s remarkably down, but it’s not over,” said Frank Mahoney, who leads the U.S. Centers for Disease Control and Prevention team here. “There are tremendous challenges still.”

The sharp decline makes this a deceptively dangerous time, a period when the virus may infect a few individuals here and there, instead of racing through whole communities, said Hans Rosling, a Swedish physician and statistician who has been serving as an adviser to the Liberian government. In far-flung communities, one infection can soon lead to dozens more, as Liberia has learned painfully, he said.

Indeed, the CDC is dispatching teams to hot spots around the country, hoping to stop the virus after a single reported case, through contact tracing and isolation of patients.

“We’ve won the first phase of the epidemic. We are now in a different phase that is not so visual, but it’s just as dangerous,” Rosling said. “In September, this city was under attack by an army of virus. We defeated that army. But now we have terrorists in every part of the country.”

Doctors Without Borders, which led the fight against Ebola in the darkest days of the epidemic, has no plans to reduce the size of its treatment center, although it is was only about one-third full Monday.

“We really want to keep this up for now, because we don’t know what’s going to happen,” said Natasha Reyes, medical coordinator for the facility. “The numbers have gone down, it’s quite clear. But we have seen in Guinea and Sierra Leone that the numbers go down and come back up.”

Instead, the organization is using the time provided by its declining caseload to reduce the length of shifts medical personnel must serve in stifling hot moonsuits and to step up prevention and education efforts in the community.

Rosling said the virus “plateaued” at about 80 confirmed cases a day across Liberia during the last week of September and the first week of October. Had there been time and resources to test more of the dead, he said, the total might have been 50 or even 100 percent higher.

The numbers have steadily fallen since, and now there are about 20 to 30 confirmed cases a day, he said.

Theories abound about the reasons for the newfound success against Ebola, but most people involved mention a potent combination of several factors: the opening of more treatment beds, breakthroughs in convincing Liberians that Ebola is real and very dangerous, widespread acceptance of “safe burials” and cremations that prevent families from touching highly infectious corpses, and the mobilization of entire communities to quickly identify and isolate infected individuals before they can transmit the virus.

“The virus is in the community, and the best way to take it from the community is for the community itself” to take charge, said Archie C. Gbessay, coordinator of the Active Case Finders and Awareness Team in West Point, a vast Monrovia slum. “That is what we thought.”

Huge obstacles remain. Travel between Guinea, Sierra Leone and Liberia, especially now that the rainy season is ending, means that the virus can repeatedly reenter places that have stamped it out, experts said. The outbreak cannot be considered eliminated until it has been stopped in all three countries, the CDC’s Mahoney said.

Liberia’s non-Ebola health system, which virtually collapsed at the height of the epidemic, must be rebuilt in a way that protects health workers from infection by the virus. And even the smaller number of infections seen here now remains a sizable problem.

“Starting from where we came from, [current conditions] look like a cakewalk,” Mahoney said. “But in any other country, this would be a crisis of enormous proportions.”

Samwar Fallah contributed to this report.