NYC health officials investigate cluster of 14 Legionnaires' disease cases

The New York City Department of Health and Mental Hygiene is currently investigating a community cluster of 14 cases of Legionnaires' disease in in the Upper East Side neighborhoods of Carnegie Hill and Yorkville (ZIP codes 10028 and 10128). To date, there are no deaths associated with this cluster.

Legionnaires' disease is a type of pneumonia. It is caused by bacteria (Legionella) that grow in warm water. The illness is not contagious between people. Transmission occurs when individuals inhale mist or water vapor containing the bacteria. While most people exposed to the bacteria do not become ill, those over the age of 50, cigarette smokers, individuals with chronic lung disease, and those who are immunocompromised are considered to be at an increased risk.

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Public Health Guidance and Safety

The Department of Health has issued guidance confirming that it remains safe for residents to consume tap water, cook, and bathe as usual. Furthermore, officials emphasize that the bacteria do not spread through cooled air from air conditioning units. Residents are encouraged to continue using home air conditioning, city facilities, and cooling centers, which remain vital resources during the current extreme heat.

Medical providers have been directed to remain vigilant and report any potential cases to the city promptly to ensure early detection. Treatment for the disease relies on antibiotics, which are effective when the condition is identified early. Residents who have lived, worked, or visited the affected neighborhoods since late June are advised to monitor their health and contact a medical provider immediately if they experience symptoms, which include:

• Fever and chills
• Cough and difficulty breathing
• Muscle aches
• Headaches and fatigue
• Confusion, diarrhea, or loss of appetite

Environmental Investigations

The city's ongoing investigation into the current cluster focuses on identifying the source of the bacteria, with health authorities actively sampling and testing cooling towers throughout the area. In urban environments, these towers can harbor Legionella if not properly maintained, releasing contaminated vapor into the surrounding air. New York City regulations mandate that building owners register their cooling towers, perform routine testing, and adhere to maintenance schedules. Should any cooling towers return positive results during the current investigation, the responsible building owners will be legally required to perform full disinfection and remediation protocols under city oversight.

This investigation follows separate, localized findings. Earlier this year, health inspectors identified Legionella within the plumbing system of the Cherokee apartment complex, located between East 77th and East 78th Streets. That evaluation was triggered after two cases were reported in the same building within a 12-month period, which is the standard threshold for a mandatory building investigation. In that instance, management worked with water safety professionals to treat the building’s water supply.

The emergence of the current cluster has prompted renewed community concern regarding the oversight of industrial equipment. Some residents have pointed to the 2025 outbreak in Harlem, which sickened 114 people and resulted in seven deaths, as a reference for the potential severity of such cases. During that event, officials traced the source to 12 cooling towers at 10 buildings.

Future Monitoring and Next Steps

As the Health Department continues its testing throughout Carnegie Hill and Yorkville, officials are conducting the following actions:

• Ongoing Environmental Testing: Health teams are sampling water systems throughout the affected neighborhoods to pinpoint the specific source of the Legionella.
• Clinical Vigilance: Medical providers remain on alert to report cases, facilitating timely medical intervention.
• Remediation: Any infrastructure found to be contaminated will be subjected to mandatory disinfection and remediation measures.

Residents are encouraged to consult the city's official health portal for updates on inspection results and building-specific information as the investigation proceeds.