Third person dies from Legionnaires' disease in NYC cluster

A  third person has died of Legionnaires’ disease after the recent outbreak on the Upper East Side, the city’s Health Department announced Sunday.

“It is with great sadness that I report a third person has died in connection with the Legionnaires’ disease community cluster on the Upper East Side. Our hearts are with their family and friends as they mourn their loss," Health Commissioner Alister Martin said in a statement.

The department identified a cluster of Legionnaires’ disease, a lung infection caused by inhaling water droplets containing the Legionella bacterium, on the Upper East Side, Carnegie Hill and Yorkville earlier this month. The first two cases in this cluster were reported on July 2 and as of Saturday, 7472 people had been diagnosed. The first death was reported on Friday and the second on Saturday. 

Many cases of the disease are traced to buildings with large cooling systems, hot water tanks, water fountains and hot tubs. Symptoms include headaches, muscle aches, fever, nausea, coughing and chest pain, according to the Mayo Clinic in Minnesota. It is not contagious and can be treated with antibiotics, but in older people or those with compromised immunity, it can be serious or fatal, experts say.

In the past two weeks, 183 cooling towers were inspected and tested for the Legionella bacterium, and 76 towers that had initial positive results were cleaned and disinfected, following the department’s orders. In the past, disinfection was required only after a culture came back positive, but that takes several weeks, during which time more people could be exposed.

The number of new cases in New York City has slowed, the health agency said.

"While we continue to investigate cases and closely monitor those in the hospital, we have not identified anyone with new symptoms for more than a week, and we are not seeing any concerning trends in emergency department surveillance data," Martin said. "We believe the source of exposure has likely been eliminated due to our aggressive remediation and enforcement efforts." 

The agency said fewer diagnoses suggested the source of the outbreak had been addressed.

Of the 74 people who were diagnosed, 51 have been released from the hospital while eight patients are still being treated.

The announcement said the agency continues to monitor towers that tested positive.

The city Health Department said it has also stepped up routine inspections of cooling towers in the first six months of this year, after Mayor Zohran Mamdani took office, increasing checks by 35% over the same period in 2025.

Newsday's Janon Fisher contributed to this story.