NYC Dealing With South Bronx Legionnaires’ Disease Outbreak

The New York City Health Department on September 13 ordered 10 cooling towers in the South Bronx to be cleaned and disinfected as the city continued its investigation into the latest community cluster of Legionnaires’ disease.

As of September 12, nine people had been diagnosed with Legionnaires’ disease in connection with the South Bronx cluster. Three people remained hospitalized, four had been discharged and one person did not require hospitalization. One person has died, according to the city.

All 10 cooling towers are located in ZIP codes 10451 and 10456 and are required to complete remediation by September 14.

This Legionnaires’ disease emergency follows one in July on the Upper East Side in which more than 90 cases and seven deaths were reported.

This latest incident also comes one month after New York Gov. Kathy Hochul signed legislation strengthening regulations on cooling tower inspections. The new law requires that owners and operators of cooling towers in New York City certify that their cooling towers have been inspected, tested, cleaned, and disinfected in compliance with the New York City Administrative Code.

In the South Bronx case, the health department launched an investigation on September 10 after identifying a cluster of Legionnaires’ disease cases in Melrose and Morrisania, which are part of ZIP codes 10451 and 10456. The health department said it began canvassing the affected neighborhoods and sampled all 24 cooling towers in the area.

On September 12, the agency issued orders to clean and disinfect the 10 cooling towers that tested positive for the presence of Legionella bacteria through an initial PCR (polymerase chain reaction) test. This test can detect the presence of Legionella bacteria DNA but cannot determine whether the bacteria are alive or dead and does not confirm that a cooling tower is the source of exposure.

The city is also conducting culture testing to determine whether live Legionella bacteria were present when the samples were collected. Culture results can take up to two weeks.

The department said it has completed all annual inspections in 2025 and is on schedule to complete annual inspections for 2026. Citywide, 82% of cooling tower systems are in compliance with the monthly testing requirement, according to the city.

The health department held a virtual town hall on Sunday and has scheduled an in-person town fall for Tuesday.

Legionnaires’ disease is caused by Legionella bacteria that grow in warm water. The disease spreads through water vapor that contains the bacteria. It is a type of pneumonia that causes flu-like symptoms, including fever, chills, muscle aches, and cough. Anyone who lives, works, or has visited the South Bronx area since late August and develops flu-like symptoms should contact a health care provider immediately.