Legionnaires' Disease
Legionnaires' disease is a type of pneumonia. It is caused by bacteria (Legionella) that grow in warm water. Legionnaires' disease causes flu-like symptoms, and complications from the disease can be serious and even fatal, if left untreated.
People who breathe in water vapor (mist) that contains Legionella bacteria can get sick.
Most people who are exposed to the bacteria do not develop Legionnaires' disease. Illness usually occurs after high or repeated exposure, especially in people who are at increased risk.
Legionnaires' disease is not contagious — you cannot get it from someone else. You cannot get Legionnaires' disease by drinking water, cooking, or using air conditioning. The bacteria that cause Legionnaires' disease does not spread through cooled air from air conditioners.
You are at an increased risk for Legionnaires' disease if you:
- Are age 50 or older
- Smoke or vape
- Have a chronic lung disease
- Have a weakened immune system
- Take medicines that weaken your immune system
When there are multiple people in a neighborhood with Legionnaires' disease (community cluster), common sources of exposure are cooling towers, hot tubs, and spray fountains.
At other times, when there are multiple people with Legionnaires' disease who live in the same building (building cluster), the exposure is typically related to a building’s plumbing system — most often the hot water system. When this happens, a building’s residents can be exposed through water mist when they shower.
When there are two or more confirmed cases of Legionnaires' disease within a 12-month period associated with the same building with a shared hot water system, the Health Department will conduct a building evaluation.
Symptoms
Legionnaires' disease symptoms include fever, chills, muscle aches, and cough. People may also have headaches, fatigue, loss of appetite, confusion, or diarrhea.
If you have these symptoms, seek medical attention. It is especially important for people at increased risk for Legionnaires' disease to seek care right away. Tell your health care provider you are worried about Legionnaires’ disease.
Prevention
There is no vaccine or medicine that can prevent Legionnaires' disease, but it can be treated with antibiotics, and most people get better with early treatment. The best way to prevent the disease is through the proper maintenance of water systems where Legionella may grow.
In NYC, building owners are required to register cooling towers. This allows the Health Department to quickly investigate when we are notified of clusters of Legionnaires' disease cases. Building owners also need to routinely test the water in the cooling tower for the presence of Legionella and do routine checks of their system as required by NYC cooling tower regulations. They also need to routinely test the water for the presence of Legionella. You can look up results of Health Department inspections of cooling tower systems by building address or building identification number (BIN).
The Health Department investigates clusters of Legionnaires' disease cases to find the source of the contamination in order to prevent other people from getting sick.
Additional Resources
- Legionnaires' Disease: What You Need to Know Poster (PDF)
Other Languages: Español | Русский | 繁體中文 | 简体中文 | বাংলা | Kreyòl ayisyen | Français | العربية | 한국어 | Italiano | Polski | ײִדיש | فارسى - Legionnaires' Disease: What You Need to Know Postcard (PDF)
Other Languages: Español | Русский | 繁體中文| 简体中文 | বাংলা | Kreyòl ayisyen | Français | العربية | 한국어 | Italiano | Polski | ײִדיש | فارسى - Legionnaires' Disease Annual Surveillance Report (PDF)
- Water Management Program Template (PDF)