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The New York City Department of Health and Mental Hygiene identified Harlem Hospital and the site of the city’s new public health laboratory as the sources of the Legionnaires’ disease outbreak in Harlem that has resulted in more than 100 cases and seven deaths.
The agency used molecular analysis to identify genetic matches between water samples taken from the two sites’ cooling towers and samples from people sickened by the disease, Dr. Michelle Morse, the Health Department’s acting commissioner, said in a virtual press briefing on Friday. The city-run hospital is located at 506 Lenox Ave., next door to the construction site at 40 W. 137th St. where the laboratory is being built.
Morse also declared the outbreak over, reporting that while six people remain hospitalized with the disease, no one who lives or works in the area has reported new symptoms since Aug. 9. In total, 114 people were sickened with Legionnaires’ and 90 hospitalized since late July.
“While today marks a hopeful step forward for our city, I recognize that we are also grieving,” Morse said.
Legionella bacteria occurs naturally in lakes and streams and does not usually pose a risk to human health unless it enters a building’s water system or cooling tower system and multiplies in warm temperatures. People can become sick by inhaling water droplets containing the bacteria.
While most people exposed to Legionella do not get sick, some are at greater risk of developing Legionnaires’ disease. At-risk groups include current or former smokers, people at least 50 years old, and those with health conditions including cancer, chronic lung disease, diabetes, kidney failure, liver failure, and weakened immune systems, according to the Centers for Disease Control and Prevention.
At least 90% of the people sickened by the disease in the Harlem cluster — 104 people — had risk factors for severe disease, according to the Health Department.
Harlem Hospital compliant with regulations, but tested positive
The Health Department’s investigation into the disease cluster began on July 25. Through PCR testing of water samples from cooling towers in Central Harlem, the city identified a dozen cooling towers with positive tests for Legionella. The agency also used “gold standard” culture tests to determine which cooling towers had live, illness-causing bacteria.
But it wasn’t until completing molecular analysis that the city identified which cooling towers were responsible for the outbreak. Those cooling towers have been fully remediated and sanitized, and the city is working with the buildings to develop long-term Legionella management programs, Morse said.
The Health Department reported that it took water samples from Harlem Hospital on July 25. Five days later, the hospital disinfected the cooling tower, and the Health Department found it to be in compliance with regulations. On Aug. 7, the hospital drained, disinfected, and refilled the cooling tower after the Health Department’s culture test returned a positive result.
Dr. Mitchell Katz, the president and chief executive of NYC Health + Hospitals, said that Harlem Hospital was “fully compliant with the law” and had conducted weekly testing of its cooling towers. The hospital had preemptively disinfected the cooling tower on July 2, “because we’re all aware, summer months, standing water, nature is very powerful,” Katz said. He noted that previous tests of the cooling towers had returned negative.
“Harlem Hospital is the perfect example of full compliance with the rules, and yet, we did, on one of the tests, as has been explained, have a positive result,” he said.
According to city records, routine inspections of cooling towers at Harlem Hospital in July 2024 and October 2024 resulted in no violations. As part of the outbreak investigation, the Health Department also conducted an investigation of the hospital’s cooling towers on July 30, which also found no violations, said Corinne Schiff, the Health Department’s deputy commissioner for environmental health.
“The way that the law works, and the way it has to work, is that the owners need to do this routine, constant oversight and maintenance of their cooling towers,” she said.
City-owned construction site also outbreak source
The construction site on 137th Street, where the city’s new public health laboratory is being built, is overseen by the New York City Economic Development Corporation and managed by Skanska USA, a contractor. Morse said the site’s cooling tower was not registered with the Health Department until July 30, two days after the agency sampled it and received a positive Legionella result. Skanska USA completed the remediation of the cooling tower on Aug. 1, according to the agency.
Last week, Nunzio Quinto, a Nassau County electrician working at the site who was diagnosed with Legionnaires’ disease, filed a lawsuit against Skanska USA, alleging that the company did not ensure safe working conditions.
In a press conference in Harlem on Aug. 20, Quinto said that he had started to feel fatigued in late July and thought he had food poisoning, but was soon diagnosed with Legionnaires’ disease and hospitalized for multiple days.
“I can’t have a safe place to work? This is New York City,” Quinto told reporters.
Another worker from Nassau County, Duane Headley, filed a lawsuit against another general contractor after developing Legionnaires’ disease while working at the Harlem Hospital complex.
Reforms proposed to prevent future outbreaks
Morse announced a raft of policy proposals in response to the outbreak, including requiring building owners to test for Legionella every 30 days instead of every 90 days when cooling towers are in use, and increasing fines for violations of city regulations.
She also said the Health Department would request to hire additional water ecologists and inspectors. While she did not provide specifics on headcount or budget, she noted support from City Hall for the new hires.
The Health Department’s number of cooling tower inspectors dwindled in the lead-up to the outbreak, as Gothamist has reported. Morse and other Health Department officials emphasized that while the agency was short-staffed for routine investigations, it was able to rapidly respond to the initial outbreak in Harlem.
The Health Department will also conduct a full review of existing rules to strengthen regulations, Morse said, and Mayor Eric Adams’ administration has proposed establishing a community engagement team of community health workers to be deployed during outbreaks.
“We will redouble our efforts to ensure that this doesn’t happen again by implementing a series of reforms based on this experience,” First Deputy Randy Mastro said during the briefing.
The Health Department is conducting two other Legionnaires’ disease investigations, at the Parkchester North Condominium and the Parkchester South Condominium in the Bronx. At both sites, at least two cases of Legionnaires’ disease were diagnosed within a 12-month period. Morse emphasized that those investigations are separate from the Harlem outbreak.
Eliza Fawcett is a reporter covering public health in New York City for Healthbeat. Contact Eliza at efawcett@healthbeat.org.
