NYC Legionnaires' disease outbreak July 2026
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A Sensible New Yorker's Guide to Legionella Season
Legionnaires' disease has a 10 percent fatality rate.
The Ardsley's hot-water system tested positive for Legionella.
Legionella spreads through mist or vapor generated by cooling towers, not from person to person.
Legionella positive tests more than double in Upper East Side buildings
The number of new Legionnaires' diagnoses peaked on July 6.
The Legionnaires' outbreak affected three ZIP codes on the Upper East Side: 10028, 10128, and 10075.
City health officials released a list of 45 new buildings whose cooling towers tested positive for Legionella on Tuesday evening.
NYC Legionnaires' outbreak: cooling towers test positive for Legionella
As of Wednesday evening, 22 people who were sick had gone to hospital, with some treated in the intensive care unit.
New York City Mayor Zohran Mamdani said officials had tested all of the cooling towers in the area.
In the 2025 Harlem outbreak, 114 people were infected and seven people died.
“Our facilities are regularly tested, and like hundreds of other cooling towers at buildings and facilities across the affected area, have been examined again in recent days, with one showing a positive result. In an abundance of caution, we have sanitized all three NYC Transit cooling towers on Second Avenue and will be subsequently retesting,”
Legionnaires' disease outbreak on Upper East Side near Central Park
No fatalities had been reported in the outbreak.
The outbreak covers zip codes 10028, 10128, and 10075 on the East Side of Manhattan.
Legionnaire's disease can typically be treated through antibiotics but can be fatal if left untreated.