At least 93 patients have tested positive for cholera at a single hospital in Myanmar’s biggest city, officials said, as an outbreak that began last week spread across the region.

They are among more than 180 people in the city, Yangon, who have been hospitalized with diarrhea, a common symptom of the disease, Dr. Nanda Win, the head of the Yangon Region Public Health and Medical Services Department, said Friday. One 92-year-old man had died, he said.

The outbreak is the latest strain on Myanmar’s faltering medical system, which has been neglected under a junta rule that has prioritized weapons over health budgets.

Dr. Nanda Win said cases were concentrated in downtown Yangon, many of them in Chinatown, and identified contaminated water and takeaway street food as possible sources. Officials are still tracking where patients live and have traveled to determine how widely the disease has spread.

Authorities were preparing supplies at 83 other hospitals across the Yangon region and working to ensure that the water supply was safe, he said.

Cholera outbreaks are not unusual in Myanmar, but experts say they are rare in the Yangon region and attribute the latest outbreak to poor sanitation.

Dr. Tin Tun, a doctor and former district chairman in Yangon, said food outlets had not been properly inspected, water for cleaning was insufficient and drainage systems were no longer being properly maintained.

While Yangon General Hospital was prepared to treat cholera patients, he said, facilities elsewhere might not be. “If it spreads to other towns and villages where health care services are weak, I am worried that the death rate could be higher,” Dr. Tin Tun said.

There have also been reports of cholera outside the Yangon region.

“We have also seen cases among people returning from Yangon,” said Aung Myo, an ambulance worker in Kyaikkhami, Mon State.

He cited the cases of a 34-year-old man and a 59-year-old woman who tested positive after returning from Yangon. Some of their traveling companions and family members have been quarantined.

Sithu Phyo, a 15-year-old Yangon resident, said he began having diarrhea and vomiting about two hours after eating a fermented fish salad with his family last week.

By the next day, his legs were cramping and he was too weak to walk. “My face had become very thin, my eyes and cheeks were sunken, and I was shaking,” he said. His family rushed him to a hospital, where he was diagnosed with cholera and given intravenous fluids.

Myanmar has battled infectious diseases for years as civil war has gutted its health care system. The country has one of the world’s largest populations of children who have never received a vaccine, according to UNICEF. Much of the progress made against disease under civilian rule was reversed when the military seized power in 2021. Poverty and conflict — both of which can contribute to cholera outbreaks — persist. According to some analysts, the junta has recently intensified its bombings of unarmed populations.

The outbreak comes amid some of the worst monsoon rains in years, according to local news outlets.

Severe flooding can contaminate water supplies and increase the risk of cholera outbreaks, a threat that climate change has compounded, according to the World Health Organization.

Cholera, an intestinal infection caused by consuming food or water contaminated with the bacterium that causes the disease, can cause diarrhea, vomiting and, in severe cases, dehydration that can lead to kidney failure and death. As many as four million people contract cholera worldwide each year, and as many as 143,000 people die from it, according to the U.S. Centers for Disease Control and Prevention.

Since last week, Yangon officials have intensified efforts to disinfect the city’s water supply by injecting chlorine into pipelines, according to the city’s sanitation department. Health officials are also quarantining people who have been in close contact with those who tested positive.

If all goes to plan, “we expect the number of cases to drop significantly within a week,” said Dr. Nanda Win.