SOUTH BRONX — The New York City Health Department announced an investigation into a cluster of Legionnaires' disease in the South Bronx on Thursday after one person died and five others were diagnosed. As of September 10, 2026, confirmatory results for other potential cases remain pending while officials work to identify the source of the bacteria.

The confirmed cases are located in the Melrose and Morrisania neighborhoods, specifically within ZIP codes 10451 and 10456. Health Commissioner Alister F. Martin addressed the situation in an official statement regarding the ongoing probe.

Martin said that disease investigators have confirmed five cases of Legionnaires’ disease and are working quickly to identify and confirm any additional cases in the area. He added that one person had died and that condolences were being extended to their loved ones.

Martin acknowledged public anxiety surrounding the new cluster given recent history in other parts of the city. He said New Yorkers may have heightened concerns following the recent Upper East Side cluster and that immediate action was being taken.

Legionnaires' disease is a form of pneumonia caused by Legionella bacteria, which can grow in warm water systems including cooling towers, showerheads, sink faucets, hot tubs, and vehicle windshield wiper fluid tanks. The illness is not contagious and can be treated with antibiotics when caught early, though symptoms such as fever, chills, muscle aches, and cough can develop two to 14 days after exposure.

People aged 50 and older, smokers, and those with chronic conditions or weakened immune systems are at increased risk of developing the disease. New York City health officials state it is safe to use air conditioners, drink tap water, and shower unless otherwise advised.

Sampling of cooling towers in the affected area has been completed, and testing is underway at the city’s public health laboratory. Building owners whose cooling towers test positive for Legionella bacteria are directed to drain, clean, and disinfect them.

The health department issued a health alert to providers advising them to consider Legionnaires’ disease when evaluating patients with compatible symptoms. Community health workers will canvass the neighborhood as part of the response, and the health department plans to begin community outreach, including canvassing and town halls, on Friday. Martin said that anyone who lives, works, or has visited the affected area since late August and is experiencing flu-like symptoms should contact a health care provider as soon as possible.

In a separate incident, an air-conditioning tower at the NYPD’s 112th Precinct in Queens tested positive for trace amounts of Legionella bacteria on September 2. The bacteria level at the location was categorized as "Level 2," which is considered low risk and does not require occupant notification under state law.

Records indicate there are 38 active cooling towers across 26 buildings in the two Bronx ZIP codes identified as affected by the current outbreak. As of June 17, health officials had inspected 82% of the cooling towers in the affected area in the past year.

Gothamist identified five buildings in the affected South Bronx ZIP codes that did not submit proof of bacterial testing to the city health department in the weeks leading up to the outbreak. City Council Speaker Julie Menin commented on the response efforts in an online statement.

Dais said that after seeing what happened in Harlem and the Upper East Side, being proactive is the best way to stop further spread of Legionnaires. The Health Department will host a virtual media briefing tonight at 8:00 p.m. on September 10, 2026.

Why It Matters

The recurrence of a community cluster within months of a deadly outbreak on the Upper East Side shows the ongoing challenge of managing Legionella bacteria in urban infrastructure. With 38 active cooling towers in the immediate vicinity and compliance questions among some building owners, the investigation focuses on preventing further transmission in a densely populated area.

The public health response involves both immediate containment measures, such as cooling tower sampling and disinfection, and broader community outreach to ensure residents seek timely medical care. The distinction between this cluster and the unrelated finding at a Queens police precinct shows the targeted nature of the current investigation in the South Bronx.

Timeline

This is the second community Legionnaires’ disease cluster identified in New York City in recent months, following a cluster on Manhattan’s Upper East Side identified in July.

An air-conditioning tower at the NYPD’s 112th Precinct in Queens tested positive for trace amounts of Legionella bacteria on September 2. As of September 10, 2026, five people have been diagnosed with Legionnaires’ disease in the affected area, with confirmatory results for other potential cases pending, and one person has died in connection with this cluster.

What's New

A study titled "Probable Person-to-Person Transmission of Legionnaires’ Disease" was published in 2016 in New England Journal of Medicine. Research titled "Lack of Evidence for Person-to-Person Transmission of Legionnaires' Disease" was published in 1983 in Journal of Infectious Diseases.

Research titled "Community-Acquired Legionnaires’ Disease Presenting With Gastrointestinal and Neurological Symptoms Without Respiratory Complaints in an Elderly Male" was published in 2025 in Cureus.

A study titled "The Stafford outbreak of Legionnaires’ disease" was published in 1990 in Epidemiology and Infection. No patients with confirmed Legionnaires’ disease have reported working at the 112th Precinct, and there are no public health concerns related to that location. Menin said that the priority must be protecting New Yorkers and ensuring that every available measure is being taken to contain this outbreak and prevent further illness.