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 chronic heart, lung, kidney, or liver disease or diabetes
• Have a weakened immune system due to a medical condition or medication

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.

• Legionnaires’ Disease and Building Evaluations (PDF)
• Copper Silver Ionization Water Treatment and Health (PDF)

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 healthcare provider you are worried about Legionnaires’ disease.

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.

The NYC Health Department has concluded its investigation of a community cluster of Legionnaires' disease in the Upper East Side neighborhoods of Carnegie Hill and Yorkville (ZIP codes 10028, 10128, and 10075). The source of the Legionella bacteria has been eliminated.

As of August 28, no one is still in the hospital, 11 people have died and 94 cases have been identified.

Cooling Tower Remediation Results

• 183 cooling towers at 160 buildings have been tested for Legionella bacteria. Of those:
• 77 cooling towers at 75 buildings tested PCR positive for the presence of Legionella bacteria in initial testing.
• 59 cooling towers at 58 buildings tested culture positive, confirming the presence of live Legionella bacteria. All have been cleaned and disinfected.
• In total, 124 cooling towers have tested culture negative.

Learn more about what it means when a building tests culture positive and to see the full list.

Patients Newly Diagnosed with Legionnaires' Disease in the Upper East Side Cluster

Diagnosis date is the date the specimen that tested positive was collected from the patient. No cases were diagnosed after July 21. Data are preliminary and subject to change.

Legionnaires' Disease Investigation

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A culture positive cooling tower may or may not be the source of Legionella bacteria exposure in the current cluster.

• Cooling Tower Confirmatory Culture Results (PDF, July 29)
• PCR-Positive Cooling Tower Systems (PDF, July 14)

Additional Resources

• Legionnaires’ Disease: Frequently Asked Questions (PDF, July 10)
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• Notice to Carnegie Hill and Yorkville About Legionnaires’ Disease (PDF, July 10)
  Other Languages: Español | Русский | 繁體中文 | 简体中文 | Français | Kreyòl ayisyen | 한국어 | বাংলা | Italiano | Polski | العربية | اردو | ײִדיש
• Watch: Legionnaires' Disease Virtual Town Hall, recorded July 13
• NYC Health Department Releases Preliminary List of Buildings Ordered To Clean and Disinfect Their Cooling Towers in Upper East Side Legionnaires Disease Community Cluster, July 10