A fourth person has died in connection with the Legionnaires’ disease outbreak on Manhattan’s Upper East Side, New York City health officials confirmed. The announcement came just hours after Mayor Zohran Mamdani said authorities believe the source of the outbreak has been eliminated.
According to the New York City Department of Health, 76 confirmed cases have been identified. As of Monday evening, seven patients remained hospitalized. The latest fatality was reported one day after the third death, marking the fourth consecutive day that a death linked to the outbreak was announced.
Although officials believe the outbreak is now largely under control, concerns remain among residents of the Upper East Side, nearly three weeks after Legionella bacteria were first detected in the neighborhood.
"We believe we have now eliminated the source of exposure. Nevertheless, we will continue inspecting cooling towers and strictly enforcing public health regulations," Mayor Mamdani said. He also expressed condolences to the families of those who lost their lives.
One of the victims was an 88-year-old man whose attorney said he became critically ill without warning. According to the lawyer, the man had been sitting in his apartment reading by an open window when his wife returned home and found him with a fever of 104°F (40°C).
Legionnaires’ disease is a severe form of pneumonia caused by Legionella bacteria, which multiply in warm, stagnant water. Health officials have focused their investigation on cooling towers used in large building air-conditioning systems. Building owners have been instructed to drain and disinfect any towers that tested positive for the bacteria.
Mayor Mamdani reassured residents that New York City's tap water remains safe for drinking, bathing, cooking, and household use, and that home air-conditioning systems do not pose a risk.
According to the U.S. Centers for Disease Control and Prevention (CDC), Legionnaires’ disease can usually be treated with antibiotics, but approximately 10% of patients die from complications.
Last year, a separate outbreak in Harlem resulted in more than 100 infections and seven deaths.
Health officials continue to advise anyone who has spent time in the affected ZIP codes 10028, 10075, and 10128 to seek medical attention if they develop flu-like symptoms, as the disease can appear up to 14 days after exposure.
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