18 New Cases as Legionnaire’s Disease Outbreak Hits UES
The outbreak has resulted in 18 cases as of Monday, July 6, with health officials asking members of the public who have visited eastern Central Park—between East 76th Street and East 97th Street—to monitor for symptoms.
| 06 Jul 2026 | 05:05
A new Legionanire’s disease outbreak has struck the Upper East Side, resulting in 18 cases so far. Health Department Commissioner Alistair Martin spread the news locally on July 4 (above). (
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Warning on the NYC Health Dept. which instructs residents on the UES to take steps while the department investigations or origins of the latest outbreak of Lenionnaires’ Disease. (
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Health officials are testing cooling towers in the area for the presence of the disease. Pictured above: a generic example of a cooling tower. (
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Legionnaire’s disease has broken out on the Upper East Side yet again, with 18 cases reported from one cluster as of Monday, July 6. Affected ZIP codes include 10028, 10128, and 10075. No deaths have been reported.
The NYC Health Department has been investigating the outbreak for days, Mayor Zohran Mamdani said in a social media post on July 5. He told local residents—or visitors to the area since late June—to contact a healthcare professional if they experience flu-like symptoms such as cough, fever, or trouble with breathing.
Specifically, people who have visited the east side of Central Park—between East 76th Street and East 97th Street.—have been told to monitor for symptoms.
“The collection of water samples, laboratory testing and community outreach has been ongoing throughout the Fourth of July holiday weekend,” Mamdani wrote.
“This is not an issue with any buildings’ plumbing or indoor AC units, and residents in the area are safe to drink tap water, bathe, shower, cook, and use their air conditioner at home,” he added.
Legionnaire’s disease, a severe form of pneumonia, is caused by the Legionella bacteria. It spreads via infected water vapor, and is not contagious, with most instances of exposure resulting in mild infections.
However, people in at-risk populations can contract cases that can result in serious illness or even death. There is no vaccine or cure for Legionnaire’s, although antibiotics can help with treatment.
New Yorkers at elevated risk of harm from Legionnaire’s disease include those with underlying medical conditions such as chronic lung disease, a history of smoking, or the usage of medicines that weaken one’s immune system. Residents over 50 years of age are also at heightened risk.
On July 4, Health Department Commissioner Dr. Alister Martin featured in an online video that involved him “reporting live from the Upper East Side,” where he spoke to local residents alongside community health workers.
“We’re working to identify the source. Typically it’s a cooling tower that is blowing water that has this [Legionella] bacteria,” Martin said, referring to devices situated on top of apartment buildings that release waste heat. He noted that residents could continue using their air conditioners during the severe heat wave that was still transpiring at the time.
The basins of cooling towers often serve as origin points for Legionnaire’s outbreaks, health officials have observed, due to the presence of warm water that the bacteria thrives in. Proper testing and treatment can prevent such outbreaks.
Last summer, an outbreak in Harlem sickened 114 people between July 25 and August 29, killing seven. Health Dept. inspectors traced the origins of the outbreak to ten different buildings, seven of which had not been tested for over a year as the inspection workforce shrunk.
The City Council has since passed legislation strengthening testing requirements, and inspection staffing figures have since reportedly improved. One key testing threshold is a mandated probe at any address where at least two residents test positive for Legionnaire’s within a year.
Such a probe turned up Legionella bacteria at a co-op complex on the Upper East Side, known as the Cherokee Apartments and located between East 78th Street and East 79th Street in January this year. Around the same time, a similar probe at a Harlem housing complex on Broadway turned up positive.
Likewise, a probe at an East Village housing complex—Haven Plaza on Avenue C—turned up Legionnaire’s late last month.
Unlike the current outbreak striking the Upper East Side, officials have clarified that the wider public has not been at risk of exposure during these outbreaks, as Legionella was detected in water systems that don’t spray aerosols widely. Residents living in the affected buildings had been advised to take extensive precautions such as avoiding showers, however.