A fourth person has died in New York City's Legionnaires' disease outbreak, health officials confirmed on Monday, while expressing confidence that the source of the cluster has been eliminated.
Outbreak Details and Response
The New York City health department reported that 76 people have fallen ill in the outbreak, which was traced to cooling towers in buildings on Manhattan's Upper East Side. Of those, 53 have been discharged from hospital, and 12 are recovering at home. A graph accompanying the press release showed the most recent diagnosis was on 15 July, with the peak occurring a week earlier when 13 infections were confirmed.
“At this time, we believe any source of exposure has likely been eliminated,” said Dr. Alister Martin, health commissioner of New York City, 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.”
Victim and Health Guidance
Authorities did not disclose details about the fourth victim. “We mourn their passing, and our thoughts are with their family and loved ones,” Martin said. According to the US Centers for Disease Control and Prevention (CDC), Legionnaires' disease, a serious form of pneumonia, kills about 10% of patients. The Legionella bacterium grows in warm water and can proliferate in cooling towers, hot tubs, and showerheads.
Health officials believe the source of the “community cluster” was buildings in the Upper East Side neighborhoods of Carnegie Hill and Yorkville. In all, 76 buildings tested positive for living or dead Legionella bacteria in cooling towers, including museums, private schools, and apartment houses. Their owners were ordered to drain and sanitize cooling systems.
The NYC health department statement assured residents: “This is not an issue with any building's plumbing system. 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.”
Comparison to Previous Outbreak
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 Mayor Zohran Mamdani addressed the latest outbreak 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.”
