Legionnaires' has popped up in a Bronx complex. Officials say it differs from the Harlem cases.

Caroline Lewis

Published Aug 26, 2025

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Vial of a sample that has tested positive for the presence of Legionella

Md Zakir Mahmud/Getty Images

Caroline Lewis

Published Aug 26, 2025

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A Bronx apartment complex is being evaluated for Legionella growing in its plumbing system after multiple residents tested positive for Legionnaires’ disease, a form of pneumonia caused by the harmful bacteria, city health officials confirmed on Tuesday.

The Bronx cluster — which includes four people in two buildings, diagnosed over several months — isn’t linked to the Central Harlem Legionnaires’ outbreak that has sickened more than 100 people this summer and killed six, according to city health officials.

And officials say it’s unlikely to turn into a similar public health event, since building clusters, often linked to a building’s plumbing, are considered more contained. The deadly Central Harlem cluster has instead been linked to contaminated water-cooling towers, which can emit mist with Legionella into the air and affect people in a broader area.

Testing by the city found Legionella in 12 cooling towers at 10 sites in Central Harlem that subsequently were ordered cleaned. The city, however, has not yet confirmed which of those towers is responsible for the Harlem outbreak.

“There’s a heightened sense of fear (in the Bronx cluster) because of the Harlem cluster and how fast that grew but building clusters are a lot smaller and slower,” said Chantal Gomez, a spokesperson for the city health department.

Gomez said the Bronx cluster is concentrated in two residential properties. The city health department began an evaluation of Parkchester South Condominium in the Bronx last week after two residents tested positive for Legionnaires’ within two months of each other. The city initiated a similar building evaluation at Parkchester North in June in response to two cases within a 10-month period, Gomez said.

Under the city’s protocols, when two or more residents of the same building test positive for Legionnaires’ within a 12-month period, the city orders the building owner to hire experts to evaluate how hospitable the water system is to Legionella, perform tests for the bacteria and take measures to keep it under control.

Building owners are also required to notify residents and staff so that those at higher risk — including people over 50, smokers and those with chronic lung disease — can take any necessary precautions to avoid getting Legionnaires’. Residents of the affected Bronx buildings were advised to take baths instead of showers, according to guidance shared with Gothamist by the health department.

Nia Williams, a resident at Parkchester North, said residents have received notices with some basic information about Legionnaires’ disease this summer, but added that she wanted to know more about what is being done to address the situation.

"The communication is very generic, said Williams, 33, adding that she is more concerned for her older neighbors, who are at higher risk of getting sick. “It should be a little more detailed of what exactly is going to happen, so that residents just feel a little more at ease.”

The city health department did not comment on what is specifically being done to address Legionella growth in the affected buildings.

The management of Parkchester North and Parkchester South could not be reached for comment.

The city logs between 200 and 700 cases of Legionnaires’ disease each year, according to city data. Most gain little public attention because investigators establish no link between cases and the source is never identified, according to the city health department.

Legionella bacteria is common in water systems but the risk of getting sick is very low, especially for younger, healthier people, the health department has said. A person can get Legionnaires’ disease by breathing in water vapor containing Legionella bacteria from showers, faucets or water-cooling towers, but it doesn’t spread from person to person, according to the health department.

More spread-out community clusters like the current Harlem outbreak are often linked to cooling towers. But the majority of the city’s Legionnaires’ investigations are centered around individual buildings. Between 2019 and 2022, the city ordered 31 building evaluations, while identifying two community clusters, according to a Legionella surveillance report from the health department.

Cooling towers have also gotten a lot of attention from officials seeking to control Legionnaires’ in the city. A Bronx outbreak that killed 16 people in 2015 prompted the city to regulate water-cooling towers, requiring building owners to perform regular testing and maintenance to control Legionella and report test results to the city.

Those rules don’t apply to plumbing systems. City officials said the maintenance laws are needed for cooling towers because they contain warm, stagnant water that provides ideal conditions for Legionella to grow.

“On the other hand, a building's plumbing system benefits from New York City's safe and high-quality drinking water, which is cold, constantly moving and has disinfectant,” Gomez said. The city health department maintained that the risk of getting Legionnaires’ from a building’s plumbing system is low despite the clusters that sometimes emerge.

Tagged

Health and Science

Legionnaires disease

bronx

harlem

new york city

Caroline Lewis

Caroline Lewis is on the health care beat for WNYC and Gothamist. She has covered COVID, a nurses' strike, the overdose crisis and New York’s marijuana legalization effort, and spent a year investigating patients' medical bills. She always wants to hear about how everyday New Yorkers experience the health system. Got a tip? Email [email protected].

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