Harlem Legionnaires’ refers to a cluster of Legionnaires’ disease cases that occurred in the Harlem neighborhood of New York City, typically involving outbreaks traced to contaminated cooling towers or water systems. Legionnaires’ disease is a severe form of pneumonia caused by Legionella bacteria, which thrive in warm water environments like cooling towers, plumbing systems, hot tubs, or fountains.
New York City health officials report a deadly Legionnaires' disease outbreak in Harlem, claiming two lives and sickening 58 people since July 25, 2025. The outbreak, centered in five Harlem ZIP codes—10027, 10030, 10035, 10037, and 10039—prompts urgent warnings for residents to seek medical care if symptoms arise.
What Causes It?
Legionnaires’ disease is caused by inhaling aerosolized water droplets containing the Legionella bacteria. The infection does not spread from person to person. Risk factors include:
Inhaling mist from contaminated cooling towers, air conditioning systems, or showers
Older age (especially over 50)
Smoking or chronic lung conditions
Weakened immune systems
Health authorities pinpoint 11 cooling towers in Central Harlem as the source of Legionella pneumophila, the bacteria that causes the severe pneumonia-like illness. Ordering immediate remediation within 24 hours.
“Early treatment with antibiotics can save lives,” said Dr. Tony Eyssallenne, deputy chief medical officer. The bacteria thrive in warm water systems like cooling towers, hot tubs, and large air-conditioning units, spreading through inhaled water vapor.
Legionnaires' disease triggers flu-like symptoms—fever, cough, chills, muscle aches, and breathing difficulties—within 2 to 14 days of exposure. High-risk groups include adults over 50, smokers, and those with weakened immune systems or chronic lung conditions.
If you’re in those ZIP codes that have demonstrated exposure, then we want you to monitor your symptoms and get to a healthcare provider as soon as you can so you can get access to antibiotics, because it is treatable.Dr. Tony Eyssallenne, Deputy Chief Medical Officer
Health officials urge anyone in the affected areas with symptoms to contact a healthcare provider immediately for testing and treatment.
The NYC Health Department has ramped up efforts, testing water systems and alerting doctors and community leaders. Unlike COVID-19, Legionnaires' disease is not contagious between people, but swift action is required to disinfect contaminated sources. Building owners may face fines for failing to properly maintain and sanitize water systems.
The outbreak recalls past incidents, such as the 2015 Bronx cluster that killed 16 people, highlighting the need for vigilance and prompt remediation.
Residents are urged to monitor for symptoms, especially if they have visited or live in the affected ZIP codes since late July. Regular cleaning of water systems, including showerheads and humidifiers, helps reduce risk.
Health officials emphasize that drinking water, bathing, and household air conditioners do not pose a risk. The NYC Health Department continues to work with building owners and community leaders to ensure full compliance and public safety.
One of the notable Harlem outbreaks occurred in 2015, when at least 13 people were infected in East Harlem, with one fatality reported. The city health department traced the source to cooling towers that tested positive for Legionella pneumophila.
More recent clusters in Harlem, such as in 2022, led to similar investigations. In August 2022, NYC health officials confirmed at least 8 cases in Central Harlem, with at least one death, again pointing to cooling towers as the likely source.
(Rh/Eth/VK/SE)