HANOI, VIETNAM >> Dr. Bui Xuan Hiep, head of tuberculosis control in this city’s Hoang Mai district, paged proudly through a large handwritten patient log.

“This district’s cure rate averages 90 percent,” he said. Still, Bui could see problems.

Seven patients had turned up with multidrug-resistant tuberculosis; four had been cured, two had died — and one had simply disappeared.

It’s a story repeated throughout Vietnam. The nation was once racked by a tuberculosis epidemic, one of the worst in which HIV was not the driving force. But officials fought back fiercely.

Twenty-five years ago, battered by the aftermath of a long war, chronic poverty and a heavy-handed government isolated from much of the world, Vietnam had nearly 600 cases of tuberculosis for every 100,000 residents. Today, it has less than 200.

The country boasts a 90 percent cure rate for uncomplicated tuberculosis and cures 75 percent of its drug-resistant cases, easily beating the global average, 50 percent.

Indeed, public health officials worldwide have made remarkable progress against tuberculosis. Deaths from the disease have fallen drastically since 2000, according to the World Health Organization. Tuberculosis has been halted or reversed in 16 of the 22 countries that account for the vast majority of cases.

But Ban Ki-moon, secretary-general of the United Nations, last week warned that the fight was “only half won” and estimated that 1.5 million worldwide would die of the disease this year.

There is no better example of how fragile this success may be than Vietnam. Hospital wards here are packed dangerously full, raising the risk that drug-resistant strains will spread.

The easy-to-reach patients have been treated, and many of the rest are the hardest to help: heroin-addicted couriers and laborers from the poppy fields of the nearby Golden Triangle, and mountain villagers who do not speak Vietnamese and are barely connected to the health care system.

But the biggest threat is that the money is close to running out.

“Our TB program is cost-effective and has great impact,” said Dr. Nguyen Viet Nhung, its national director. “But I always emphasize that this is a preliminary success. We need to sustain it.”

To reach Vietnam’s ambitious goal of pushing prevalence rates down to 20 cases per 100,000 residents — essentially eliminating tuberculosis as a public health problem — its tuberculosis-control program needs to spend at least $66 million a year. It now spends about $26 million a year.

About $19 million of that comes from foreign donors, with more than a third from the United States, Nguyen said.

Evidence of donor help is everywhere. The expensive diagnostic machines in hospital laboratories bear stickers from the U.S. Agency for International Development or from The Global Fund to Fight AIDS, Tuberculosis and Malaria, 30 percent of whose budget is paid by the United States. But The Global Fund, the chief support of the tuberculosis program here, is struggling and has promised support only through 2017. The White House, in its proposed budget for fiscal 2016, reduced its contribution to the fund by 18 percent and to USAID’s tuberculosis programs by 19 percent.

Officials here and at the WHO fear that hard-won progress may soon be reversed and a remarkable success story may come apart, with deadly consequences.

An ancient scourge

After years in the shadow of the AIDS epidemic, tuberculosis is regaining its notoriety as one of the world’s great killers: an airborne bacterium that spreads easily among people living crowded together — in jails, ships, mines, trenches or slums — and insinuates itself deep in the lungs and grows, slowly tearing apart the tissue until victims are coughing up blood.

Tuberculosis now kills more people around the world than AIDS, according to the WHO: 4,100 a day, compared with 3,300 dying of AIDS, making tuberculosis the leading infectious cause of death in the world.

Mortality from both diseases is dropping, but tuberculosis deaths have fallen more slowly, especially in Asia.

Vietnam’s success where so many other nations have failed is not just because of donor money, said Dr. Mario C. Raviglione, director of the WHO’s global tuberculosis program.

“It succeeds because it’s a Communist country,” he said. “Socialist countries put a lot of resources into primary care: lots of doctors, lots of clinics. And once central government adopts a thing, they really do it. They give orders.”

Tuberculosis is an ideal disease for a regimented treatment approach.

Almost all patients with “uncomplicated” tuberculosis — bacteria that are not drug-resistant — can be cured if they take a standard menu of four antibiotics every day for six months without fail.

In Vietnam, treatment standards set at the national level are followed by the entire public health network. The National Lung Disease Hospital in Hanoi oversees 64 provincial hospitals, which oversee 845 district hospitals, which oversee 11,065 neighborhood health clinics.

The pharmaceutical-supply chain, the Achilles’ heel in many tuberculosis-ridden countries, is impressive. On a weeklong tour of urban and rural clinics, not one nurse or patient reported ever running out of drugs.

Those neighborhood clinics — usually just a few examining rooms, a small pharmacy and a parking lot — are as ubiquitous here as police stations and firehouses in the United States.

They treat many illnesses, but their role in tuberculosis is simple: Every tuberculosis patient in the district reports once a day to take his or her pills in front of a nurse. Each dose taken is checked off on a yellow card.

Most patients comply without complaint, doctors say. Many poor countries are chaotic; Vietnam, while poor, is not. Parks are neatly trimmed, public bathrooms are clean, and police in gold-buttoned uniforms and high-brimmed hats are omnipresent.

Nonetheless, there are a few stubborn patients — Bui’s missing patient was a heroin addict who infected his mother with drug-resistant tuberculosis before disappearing. And the country has one surprising gap: It has no quarantine laws.

In New York City’s outbreak of drug-resistant tuberculosis in the 1990s, officials legally locked up patients who refused to take their pills. The rare noncompliant patient here faces no such threat.

“We can’t do that,” said Dr. Le Minh Hoa, head of treatment at Hanoi’s provincial lung hospital. “And besides, we don’t have enough spaces for the people who want treatment.”

Patients with drug-resistant disease are especially hard to help. Their medicines, some of which are intravenous, must be taken for two years, and can cause deafness, psychosis and kidney failure. Patients must be hospitalized, their movements restricted to one or two corridors, sometimes for months until they are no longer coughing up live bacteria.

Hospital wards are full of stooped, forlorn-looking men and women in masks and pajamas waiting to be declared well enough to go home and become a district outpatient.

If they become worse instead of better, the prognosis is usually grim. Extensively drug-resistant disease, or XDR TB, requires even more toxic drugs costing 25 times as much. Most XDR TB patients here die.

Pham Thi Tuy, 25, was an unlucky woman — she caught a drug-resistant strain, perhaps at her job as a medical technician. Facing two years of treatment, she lay hooked up to an IV in Le’s hospital, nauseated and exhausted by the drugs, watching videos on her cellphone all day.

“I only went to the doctor for an earache,” she said. “It didn’t go away and didn’t go away — and they finally did a test and said it was TB.”

She hoped her fiancE would wait two years for her to recover, she said — and then suddenly looked up at Le.

“When I finish this, will I still be able to have children?”

“Yes,” Le said, patting her hand.

Pham’s eyes crinkled behind her mask, suggesting a sweet smile, and she gave a big thumbs-up.

Limited Resources

There are many signs that the national tuberculosis program here survives on a shoestring budget.

While its top laboratories have some modern equipment, the 64 provincial hospitals share only 60 rapid diagnostic machines, less than half the number they need, even though Vietnam pays only $17,000 for each, about a tenth of the American retail price.

More ominously, hospital wards are dangerously crowded. Seven patients a room, with beds only a foot apart, is not an uncommon sight. (That effectively means 14 inhabitants a room, as many patients have a relative sleeping on the floor or in a corridor to do nursing chores and bring food.)

Windows and doors are kept open to blow away the bacteria that patients cough up. In chilly Hanoi, patients like Pham wear parkas in bed; in tropical Ho Chi Minh City, the former Saigon, they perspire in the muggy heat.

Dr. Thuy Nguyen Thu, head of the inpatient unit at the National Lung Disease Hospital, which treats the toughest cases, said four of her staff had caught tuberculosis in the past five years. New nurses were nervous, she said.

Thuy had asked for ozone air filters, better fans and safer face masks, “but there are budget limitations.”

Geography presents the tuberculosis-control program with another kind of obstacle. In the Shangri La-like valleys of Son La province, a six-hour drive west of Hanoi, some inhabitants live in villages with thatched roofs and speak only Hmong, Meo or Thai.

Finding and keeping them in treatment is hard, said Dr. Tong Van Hieu, director of the Quyet Thang neighborhood clinic in Son La. Some believe tuberculosis is caused by fog or dust or gold mine fumes, and turn first to folk remedies.

In the cities, a new problem is on the rise.

Vietnam’s growing prosperity lets some patients afford private doctors — who often ignore the official four-drug regimen and fail to insist their patients take every pill.

Pharmacists sell antibiotics without prescriptions, so some wealthy patients swallow only what they feel like taking. As a result, Dr. Phat Nguyen Ngoc, head of a district hospital in Ho Chi Minh City, said about a third of his patients with drug-resistant disease had gotten it because they had seen private doctors first and had taken too few pills, or the wrong ones.

And sometimes, even when compliant patients play by the rules, treatment fails, anyway.

In the Hanoi Lung Disease Hospital, Hoang Van Toan, a weathered farmer looking much older than his 49 years, sat wrapped in a blanket. He had taken all his pills, he said, but tuberculosis had somehow outwitted them.

The room was bare, with no television or any other diversion. “I talk to my wife,” he said, nodding at the woman sitting on the temporarily empty bed opposite him.

“And I walk for three hours every day at dawn,” he added, pointing out the window to a nearby park. He wears a surgical mask as required, he said, but that makes no one nervous in Hanoi; thousands of passing motorcyclists wear them, too.

What made him saddest, he said, is that it is still too dangerous for his grandchildren to visit.

Asked if he would make it through the next two years, he said “Yes,” emphatically.

“I was a soldier,” he added. “I fought the enemy. I can fight this.”

© 2016 The New York Times Company