Fourth person dies in New York legionnaires' outbreak as officials say source is contained

An outbreak of legionnaires' disease in New York City has claimed a fourth life, city officials said, while repeating their assessment that the source of the exposure has probably been eliminated.

A statement from the city's health department on Monday said the outbreak, traced to cooling towers in buildings on Manhattan's Upper East Side, had sickened 76 people. Fifty-three have been discharged after hospital treatment and 12 more are recovering at home. A graph accompanying the release showed the most recent diagnosis on 15 July, with the peak a week earlier when 13 infections were confirmed.

"At this time, we believe any source of exposure has likely been eliminated," Dr Alister Martin, New York City's health commissioner, wrote 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."

As with the three earlier deaths, authorities released no details about the fourth victim. "We mourn their passing, and our thoughts are with their family and loved ones," Martin said.

Legionnaires' disease is a serious form of pneumonia. It is treatable, but kills about 10% of patients, according to the US Centers for Disease Control and Prevention. The Legionella bacterium grows in warm water and multiplies in cooling towers, hot tubs and showerheads. People contract it by inhaling tiny droplets of contaminated water; it does not spread from person to person.

Investigators identified the community cluster in the Carnegie Hill and Yorkville neighbourhoods. In all, 76 buildings — including museums, private schools and apartment houses — tested positive for living or dead Legionella bacteria in their cooling towers, and their owners were ordered to drain and sanitise the systems.

The health department was emphatic that household water is not implicated. "This is not an issue with any building's plumbing system," the statement said. "Residents can continue to drink tap water, bathe, shower, cook, and use your air conditioner at home." Anyone living, working in or visiting the area since late June who develops flu-like symptoms such as cough, fever or difficulty breathing was told to contact a healthcare provider immediately.

The city has been here recently. An outbreak in Harlem in August 2025 killed seven people and sickened more than 100, following the same pattern: cases falling away quickly once the source was identified, with the outbreak declared over after about three weeks.

Mayor Zohran Mamdani addressed the deaths at a small business event on Monday. "I'm heartbroken by the loss of our fellow New Yorkers and send my deepest condolences to their loved ones," he said.