A Legionnaires’ disease outbreak in New York City has now been linked to a fourth death, city officials said, while reiterating that they believe the source of exposure has been removed.
In an update Monday, the New York City health department said the outbreak, traced to cooling towers in buildings on Manhattan’s Upper East Side, has infected 76 people. Of those, 53 have been discharged after receiving hospital care, while 12 others are continuing their recovery at home.
A chart released with the department’s statement showed that the latest diagnosis in the cluster occurred on 15 July. The outbreak appeared to peak a week earlier, when officials confirmed 13 infections in a single day.
“At this time, we believe any source of exposure has likely been eliminated,” Dr Alister Martin, New York City’s health commissioner, wrote Monday afternoon in a post on X.
“We have not seen anyone with new symptoms in over a week. We are focused on inspecting every cooling tower that tested positive and enforcing our laws to their fullest extent.”
Officials did not release identifying information about the fourth person who died, as was the case with the three earlier fatalities. Martin said: “We mourn their passing, and our thoughts are with their family and loved ones.”
Legionnaires’ disease is a severe type of pneumonia that can be treated, though it is fatal in roughly 10% of cases, according to the US Centers for Disease Control and Prevention (CDC). The illness is caused by Legionella bacteria, which thrive in warm water and can multiply in places such as cooling towers, hot tubs and showerheads.
City health officials have said the New York City “community cluster” was believed to stem from buildings in the Upper East Side neighborhoods of Carnegie Hill and Yorkville. In total, 76 buildings — including museums, private schools and apartment buildings — tested positive for either live or dead Legionella bacteria in their cooling towers. Property owners were directed to drain and disinfect the affected cooling systems.
“This is not an issue with any building’s plumbing system,” the statement from the NYC health department said.
“Residents can continue to drink tap water, bathe, shower, cook, and use your air conditioner at home.
“Any New Yorkers who currently live or work in this area or people who have visited the area since late June and are experiencing flu-like symptoms, such as cough, fever, or difficulty breathing should contact a health care provider immediately.”
People can contract legionnaires’ disease by inhaling tiny droplets of contaminated water. It does not spread person to person.
A previous outbreak in Harlem in August 2025 killed seven people and sickened more than 100. That episode followed a similar pattern with new cases trailing off quickly after the source was identified and eliminated, and officials declared the outbreak over after about three weeks.
New York’s mayor, Zohran Mamdani, addressed the latest outbreak in remarks at an event for small businesses on Monday.
“I’m heartbroken by the loss of our fellow New Yorkers and send my deepest condolences to their loved ones,” he said.
Mamdani said city officials began tracking the outbreak on 2 July after two confirmed cases. “Following the guidance of public health experts, we directed every building with an initial positive test result to immediately clean and disinfect its cooling tower,” he said.
“Due to the aggressive strategy of early testing, enforcement and remediation, we believe that we have now eliminated the source of exposure. We are continuing to inspect cooling towers and will aggressively enforce our public health laws.”
