New York identifies 76 buildings with bacteria tied to Legionnaires outbreak

The Metropolitan Museum of Art responds

The Metropolitan Museum of Art became part of New York City’s Upper East Side investigation after an initial PCR test detected Legionella genetic material in its cooling-tower system. Legionella bacteria can cause Legionnaires’ disease.

City officials said an initial positive PCR result does not prove that live bacteria were present or identify the source of infections. They also said being inside a listed building did not create additional risk.

The Metropolitan Museum of Art cleans

The Metropolitan Museum of Art said it immediately began required remediation with the city and third-party water-management specialists. The work included cleaning and disinfecting its cooling-tower system, followed by additional testing.

Because The Met Fifth Avenue is normally closed on Wednesdays, the museum canceled the few activities scheduled that day. It also directed nonessential personnel to work remotely to support the remediation process.

The Met addresses indoor risk

The Metropolitan Museum of Art said that guidance from city officials and public health experts indicated that the cooling tower finding did not pose a risk to staff or visitors inside the museum.

The institution reported more than 5.7 million visitors across The Met Fifth Avenue and The Met Cloisters during fiscal year 2025, which ended on June 30, 2025.

Famous schools join the cleanup

New York City’s July 14 list included cooling towers at addresses used by the Chapin School, Spence School, and Dalton School. Each system produced an initial positive PCR screening result.

City officials said the community investigation focused on cooling towers, not plumbing inside the listed buildings. Health guidance also says Legionnaires’ disease generally does not spread directly from person to person.

Seventy-six buildings test positive

On July 14, New York City identified 76 buildings with initial PCR-positive cooling-tower results. That was more than double the preliminary list of 31 buildings released on July 10.

At the time, 57 systems had completed remediation and 19 were due to finish by July 16. City officials later reported that all 76 systems completed the required work by that date.

What cooling towers actually do?

Cooling towers help centralized systems release heat, partly through the evaporation of water. Small droplets can escape outdoors, and warm water in a poorly controlled system can create conditions that allow Legionella bacteria to grow.

People may become sick after breathing contaminated mist. NYC said cooling-tower mist in this investigation did not affect indoor air conditioning, home window units, or plumbing inside the listed buildings.

Little-known fact: Legionella bacteria occur naturally in freshwater, but usually at levels too low to cause illness. The risk grows when bacteria enter human-made water systems.

A positive test needs context

New York City used PCR for its initial screening. The method detects Legionella genetic material quickly, but it cannot determine if bacteria detected in a sample were alive or dead.

Culture testing can confirm live bacteria. City officials said the process could take up to two weeks, meaning that an initial positive PCR result alone did not identify the outbreak source.

Little-known fact: PCR testing can detect genetic material from both living and dead Legionella bacteria.

Cleanup moves quickly across Manhattan

New York City ordered full remediation for every cooling-tower system with a positive initial PCR result. Documented measures included draining, cleaning, and disinfecting systems, followed by inspections and additional testing.

Officials called this a more aggressive strategy than the city had used during earlier clusters. Previous practice generally waited for culture confirmation before requiring complete remediation of a cooling-tower system.

The outbreak numbers keep changing

As of July 20, the New York City Health Department reported 76 cases connected to the Upper East Side cluster. Seven people remained hospitalized, 53 had been discharged, 12 had not been hospitalized, and four people had died.

Officials said the figures remain preliminary and may change as cases are investigated and confirmed. The department continued advising people who develop symptoms after spending time in the affected ZIP codes to seek medical evaluation.

Symptoms deserve prompt medical attention

Legionnaires’ disease is a potentially serious type of bacterial pneumonia. Common symptoms include cough, fever, chills, muscle aches, headache, tiredness, and shortness of breath, with illness usually developing two to fourteen days after possible exposure.

Anyone who lived, worked, or visited the affected area since late June and develops symptoms should contact a health care provider promptly. Early diagnosis matters because the illness can be effectively treated with prescribed antibiotics.

Some people face greater risk

Most healthy people exposed to Legionella do not become sick, but risk rises sharply for adults age 50 and older, current or former smokers, and people who regularly smoke or vape tobacco products every day.

People with chronic lung, heart, kidney, or liver disease, diabetes, cancer, or weakened immune systems also face higher risk. Health officials strongly urge these groups to seek prompt medical care right away if symptoms appear.

Everyday activities remain safe

City officials said residents in ZIP codes 10028, 10128, and 10075 could continue drinking tap water, cooking, bathing, showering, and using home air conditioners. The community investigation did not involve building plumbing.

Legionnaires’ disease generally does not spread from person to person. In community clusters, common exposure sources include cooling towers, hot tubs, and spray fountains that can release contaminated water droplets.

Want to learn more about other major public health concerns? See how Flint residents are finally receiving long-awaited support.

The search for answers continues

Investigators sampled 183 cooling towers and completed initial PCR screening of every system in the targeted area. Multiple positive results did not automatically reveal which tower, if any, caused the outbreak.

The city continued inspections, culture testing, and enforcement efforts, while local officials planned additional oversight. Residents were advised to watch for symptoms and follow dated public-health updates.

Another Legionnaires’ disease case is making headlines; see what happened at this Las Vegas Strip hotel.

What do you think about the city’s response to this health alert? Share your thoughts in the comments.

This slideshow was made with AI assistance and human editing.

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