THE BRONX, New York — New York City health officials are investigating a new cluster of Legionnaires’ disease in parts of The Bronx after five cases were confirmed and one person died.
The NYC Health Department announced the investigation Thursday, warning people who live, work or have recently visited the affected area to pay attention to possible symptoms.
The cluster is centered on ZIP codes 10451 and 10456, which include portions of the Melrose and Morrisania sections of The Bronx.
NYC Health Commissioner Dr. Alister F. Martin said disease investigators are continuing to search for additional cases while health officials work to determine the potential source of the outbreak.
“Our disease investigators have confirmed five cases of Legionnaires’ disease and are working quickly to identify and confirm any additional cases in the area. Sadly, one person has died, and our deepest condolences are with their loved ones,” Martin said.
The investigation comes as health officials continue monitoring Legionnaires’ disease activity elsewhere in New York City.
Cooling Towers Being Tested for Legionella
Health officials have already taken steps to investigate a possible environmental source of the bacteria.
Water ecologists have sampled cooling towers throughout the affected area, with the samples being tested at the city’s Public Health Laboratory.
Any cooling tower that tests positive for Legionella bacteria will be directed to undergo full cleaning and disinfection, according to the Health Department.
Officials are also sending community health workers into the neighborhood to help raise awareness and identify people who may have symptoms.
Martin acknowledged that residents could have additional concerns because of a recent Legionnaires’ disease cluster on Manhattan’s Upper East Side.
“I understand that New Yorkers may have heightened concerns following the recent Upper East Side cluster. We are taking immediate action,” Martin said.
Bronx Residents Urged to Watch for Symptoms
The Health Department is advising anyone who lives, works or has visited the affected areas since late August to contact a health care provider if they develop symptoms associated with Legionnaires’ disease.
Those symptoms can include fever, cough and difficulty breathing.
The city has also issued a health alert to local health care providers, asking them to consider Legionnaires’ disease when evaluating patients experiencing similar symptoms.
Officials emphasize that Legionnaires’ disease is not contagious and can be treated with antibiotics, particularly when it is identified early.
The disease is caused by exposure to Legionella bacteria, which can occur through contaminated water systems that produce an aerosol or mist.
Who Is Most at Risk?
Legionella bacteria occur naturally, and most people exposed to them do not develop Legionnaires’ disease.
However, the illness is more likely to occur after high or repeated exposure, particularly among people with certain risk factors.
People 50 and older, those who smoke or vape, and people with chronic heart, lung, kidney or liver disease, diabetes, or weakened immune systems face a higher risk of developing the disease.
Past community clusters have been linked to Legionella spreading through mist from cooling towers.
If a cooling tower is found to contain the bacteria, building owners can be directed to drain, clean and disinfect the system as part of full remediation.
Second NYC Cluster Identified in 2026
The Bronx investigation is the second Legionnaires’ disease cluster identified in New York City in 2026. The first cluster was identified on Manhattan’s Upper East Side in July.
The latest investigation also adds to a history of years in which multiple New York City communities have experienced Legionnaires’ disease clusters.
According to health officials, the city previously saw multiple community clusters in 2015, 2017 and 2018, while 2016 saw three separate community clusters.
Residents in the affected ZIP codes are being urged to remain aware of symptoms and seek medical attention promptly if they become ill.
Have you or someone you know recently visited the affected areas of The Bronx? Share your thoughts and experiences in the comments.