One person has died and five others have been diagnosed with Legionnaires' disease in a cluster now under investigation in the Melrose and Morrisania neighborhoods of the South Bronx. City health officials confirmed the cluster is centered in ZIP codes 10451 and 10456, and are urging anyone in those areas with flu-like symptoms to seek medical care right away.
Bronx Borough President Vanessa L. Gibson disclosed the death and diagnoses in a statement posted to social media
, saying her office had been made aware of the investigation by the NYC Department of Health and Mental Hygiene into what she described as a likely community cluster. Gibson said her office is in direct contact with the health department and that elected officials are expected to receive briefings from health officials over the next few days. She added that community meetings, to be held both virtually and in person, will share updates with the public as the investigation continues.
The health department formally opened its investigation on September 10, 2026, a Thursday, and environmental health teams have already completed water sampling across cooling towers throughout the affected ZIP codes, sending the samples to the Public Health Laboratory for testing, according to NYC Health. Cooling towers are considered the primary environmental vector for spreading aerosolized Legionella bacteria, which grows in warm water systems before becoming airborne through building ventilation.
City Launches Door-to-Door Outreach This Weekend
Health Commissioner Dr. Alister F. Martin announced that public health workers will begin canvassing Melrose and Morrisania starting Friday, distributing multilingual informational flyers and holding weekend town halls, per News 12. Legionnaires' disease can cause symptoms including fever, cough, and muscle aches.
Legionnaires' disease cannot spread from person to person, according to health department clinical guidance updated this month. But adults aged 50 and older, smokers, vapers, and people with chronic heart, lung, kidney, or liver disease face significantly higher risk of severe illness, and high-risk residents in the affected ZIP codes are being told to seek medical attention immediately if flu-like symptoms appear.
Second Major Cluster of an Unusually Active Summer
The South Bronx investigation marks the city's second major Legionnaires' community cluster of the summer, following a July outbreak on the Upper East Side that resulted in 11 deaths and 94 confirmed cases, the same News 12 report notes. That earlier cluster required dozens of building cooling towers to undergo mandatory chemical disinfection before it was brought under control.
The South Bronx carries a heavier history with this particular bacteria than almost anywhere else in the city. In July and August 2015, the neighborhood was the site of a major recorded Legionnaires' outbreak, which sickened 138 people and killed 16 after Legionella bacteria spread from a cooling tower atop the Opera House Hotel, according to reporting compiled by PMC. That catastrophe directly led to Local Law 77, enacted by the City Council that August, which established mandatory registration, quarterly inspections, annual certification, and routine testing protocols for building cooling towers citywide.
Regulations Have Tightened, but Outbreaks Persist
City health officials tightened cooling tower rules further in May, requiring Legionella testing every 31 days during operational months, down from the previous 90-day window, according to The New York Academy of Sciences. The city typically records between 200 and 700 sporadic Legionnaires' cases in a given year, most stemming from individual indoor plumbing or hot water systems rather than large clusters, which remain comparatively rare.
Yet clusters have struck the city repeatedly in recent summers. A 2025 outbreak in Central Harlem infected more than 100 people and caused seven deaths; attorneys were expected to announce lawsuits against the city and maintenance contractors, according to CBS New York. Hoodline previously reported on that Harlem outbreak's escalation and on residents' lingering health problems months later.
Under current city rules, building owners who fail to comply with cooling tower registration and inspection requirements face civil fines up to $10,000, while failing to disinfect a tower found harboring dangerous microbe levels is classified as a misdemeanor carrying fines up to $25,000, according to The Habitat Group. Any tower that tests positive must immediately undergo complete draining, cleaning, and biocide treatment.
Gibson's office said it will provide additional information and updates as the investigation develops, and directed residents with questions to call 311 or visit the health department's website. For now, city officials have not said whether laboratory testing has linked the illnesses to a specific cooling tower in either affected ZIP code.
