What is Legionnaires and where does it happen/grow
- Legionnaires’ disease is a type of pneumonia. It is caused by a common type of bacteria called Legionella that grows in warm water.
- People who inhale mist that contains Legionella bacteria can get sick.
- In NYC, Legionnaires’ clusters most commonly start in cooling towers of buildings with central air conditioning. Bacteria can grow in cooling towers and be carried into the air.
- Window air conditioners do not spread the bacteria that causes Legionnaires’ disease, and you can’t get it from drinking contaminated water.
Who’s at risk and how to protect yourself
- Most people who are exposed to Legionella bacteria do not get sick with Legionnaires’ disease, and it is not contagious from person to person.
- You are at a high risk for Legionnaires’ disease if you:
- Are 50 years old or older
- Smoke
- Have a chronic lung disease
- Have a weakened immune system
- Take medicines that weaken your immune system
- Legionnaires’ disease begins with flu-like symptoms and can quickly make people seriously sick.
- Symptoms can include fever, chills, muscle aches and a cough. You may also have headaches, fatigue, loss of appetite, confusion or diarrhea.
- Treatment includes antibiotics and is most effective when started quickly after symptoms begin.
- The best way to protect yourself is to seek medical attention right away if you experience any flu-like symptoms, especially if you are high risk and live, work in, or visit the affected area.
What regulations and laws are protecting NYers
- In NYC, building owners are required by law to register and maintain cooling towers. Cooling towers are routinely tested for bacteria and treated with disinfectant.
- The City also conducts yearly inspections of cooling tower systems, Maintenance Program and Plans, and operational records.
- The Health Department monitors Legionnaires’ cases. When there’s evidence of a cluster, a team of experts works to find the source and prevent other people from getting sick.
What to know about the Central Harlem outbreak
- The Central Harlem outbreak was identified by the NYC Department of Health on July 25, 2025 and covers Zip Codes 10027, 10030, 10035, 10037, and 10039.
- As of August 8, 67 cases of Legionnaire’s disease have been identified, and, tragically, 3 people have died.
- All of the cooling towers in the area were tested for Legionella last week.
- 11 cooling towers were identified as potentially positive for the bacteria and have already completed treatment to kill any bacteria that might be making people sick. They will be retested in the coming days to make sure the disinfectant worked.
- The best way to protect yourself is to seek medical attention right away if you experience any flu-like symptoms, especially if you are over 50, smoke or vape, or have a preexisting medical condition.
For the most up to date information on Legionnaires’ disease and the Central Harlem cluster, visit the DOHMH website: https://www.nyc.gov/site/doh/health/health-topics/legionnaires-disease.page
