The Solomon R. Guggenheim Museum remained open after New York City officials confirmed that Legionella bacteria had been detected in the cooling tower of the landmark Manhattan museum, one of 31 Upper East Side buildings ordered to clean and disinfect tower systems during a growing Legionnaires’ disease outbreak.

The museum’s address, 1071 Fifth Avenue, appeared on a preliminary city list released Friday. The Health Department classified the Guggenheim among 19 buildings that had already completed full remediation. Twelve other properties were ordered to finish cleaning and disinfection by Saturday. City officials said the museum was not directed to close, and the institution said no further action was required at that time.

The finding does not mean the Guggenheim caused the outbreak. The city’s initial polymerase chain reaction screening can detect genetic material from Legionella bacteria, but it cannot determine whether the organisms were alive or dead. Only live bacteria can cause illness. Health officials are conducting slower culture tests on samples from every tower, a process that can take as long as two weeks and is intended to help identify the source or sources of exposure.

The latest publicly reported city figures showed at least 54 people diagnosed in connection with the Upper East Side cluster as of July 10. Eighteen remained hospitalized, while no deaths had been reported. The cluster was first announced July 2 after two cases were identified near each other, and the investigation later expanded across the 10028, 10128 and 10075 ZIP codes.

More than 180 cooling towers have been sampled in the investigation area. Cooling towers are rooftop systems that help remove heat from large buildings by releasing water vapor or mist into the outdoor air. When Legionella grows in a tower and contaminated droplets become airborne, people nearby can become infected by breathing them in. The towers do not supply a building’s drinking water and do not send contaminated air through indoor air-conditioning systems.

That distinction is central to the city’s guidance for museum visitors, neighborhood residents and workers. Officials have said it remains safe to drink tap water, shower and use air conditioning in the affected neighborhoods. Legionnaires’ disease does not spread from person to person, and health authorities have not recommended masks as a preventive measure for this outbreak.

Legionnaires’ disease is a serious form of pneumonia. Symptoms can include fever, chills, cough, muscle aches, headache and shortness of breath, generally appearing two to 14 days after exposure. The city has urged anyone who has lived, worked or visited the affected area since late June to contact a health care provider promptly if such symptoms develop. People age 50 and older, smokers and vapers, those with chronic lung disease, and people with weakened immune systems face higher risk.

The Guggenheim said it uses outside specialists for regular monthly testing and treatment of its cooling tower and acted immediately after receiving the positive result. The museum also said the city had confirmed that there was no additional action needed and that the finding posed no risk to people inside the building. The institution said it would continue following municipal health guidance.

The response allowed the museum to continue operating without interrupting public access to its galleries or the Frank Lloyd Wright-designed building itself. The cylindrical structure, completed in 1959, is one of New York’s most recognizable cultural landmarks and is part of a UNESCO World Heritage designation covering major works by Wright. Its inclusion on the city’s list drew attention because the outbreak zone overlaps with Museum Mile and an area that receives heavy daily foot traffic from residents, tourists and museum staff.

For New York’s cultural institutions, the episode underscores that public-facing operations can be affected by infrastructure located out of visitors’ sight. Cooling towers are common in large museums, office buildings, hospitals and apartment complexes. Their maintenance has become a prominent health issue in the city because contaminated towers can disperse bacteria beyond a single property, making an outbreak a neighborhood-level problem rather than solely a building-level one.

New York strengthened its cooling-tower rules before this outbreak. Regulations that took effect in May require owners to test operating towers for Legionella at least once every 31 days, three times as often as under the prior schedule. Building owners must also register towers, maintain treatment plans and report testing. The city said its decision to publicly identify positive preliminary tests and require immediate disinfection represented a more aggressive and transparent approach than waiting for culture confirmation.

That urgency reflects the consequences of earlier outbreaks. In 2025, a Central Harlem cluster sickened more than 100 people and caused seven deaths before investigators linked the outbreak to cooling towers at Harlem Hospital and a nearby construction site. The current Upper East Side cluster has produced no reported deaths, but officials have warned that additional cases may emerge because symptoms can take up to two weeks to develop after exposure.

The city has not identified a confirmed source. Officials said the 31 positive preliminary results may include towers that contained dead bacteria and therefore posed no infection risk when sampled. Culture testing will be more informative, but the city ordered immediate remediation across the list to reduce potential exposure while those results are pending.

For now, the Guggenheim’s status is unchanged for the public: the museum is open, its cooling tower has been cleaned and disinfected, and health authorities have not advised visitors to avoid the building. The larger investigation remains active, and the number of implicated properties could change as additional laboratory results are completed.