NEW YORK — The Legionnaire’s Disease outbreak that has plagued the Upper East Side for the past month has claimed its sixth victim, city officials announced Tuesday.

“We are heartbroken to report that a sixth person has passed away in connection with the Legionnaires’ disease cluster on the Upper East Side,” city Health Commissioner Dr. Alister Martin said on X. “We extend our heartfelt condolences to their loved ones, and our thoughts are with them during this difficult time.”

Although officials believe that the source of the exposure has been eliminated, the city has identified 90 cases of Legionnaires’ disease, which is a severe form of pneumonia caused by the Legionella bacteria, since the cluster was first identified on the Upper East Side in early July.

As of Tuesday, six people exposed remain in the hospital. An additional 65 have been discharged.

“At this time, no one has reported new symptoms in over two weeks; no one has been diagnosed in over 10 days,” Alister said.

The outbreak has sparked a war of words between Mayor Mamdani and City Council Speaker Julie Menin, who has criticized his administration’s handling of the surge of Legionnaires’ cases.

Menin has accused the mayor for not ordering more proactive cleaning of cooling towers on the Upper East Side, where the outbreak occurred. But Mamdani said he was more concerned about making sure the job is done right.

“I’m frankly less interested in the politics of it all, more in the public health of it,” the mayor said in a response to a question about the Council speaker’s criticism.

Symptoms typically develop two to 14 days after exposure and include fever, chills, muscle aches, shortness of breath and coughing. The disease spreads through the inhalation of water vapor — not person to person.

Most people exposed to the bacteria do not become sick, but the disease is fatal in about 10% of cases and is most dangerous for those above age 50 or with compromised immune systems.

The city has focused on tamping down the outbreak by having buildings on the Upper East Side with cooling towers, where the bacteria can proliferate, tested for the pathogen and then ordering remediation, if needed.

At least 76 buildings were found to have the microbe and were ordered by the city to clean and disinfect their cooling systems — including the Guggenheim Museum and the Metropolitan Museum of Art, the Trevor Day School on E. 95th St., and 1110 Fifth Ave., a luxury apartment building overlooking Central Park designed by renowned architect James Edwin Ruthven Carpenter Jr.

This year’s outbreak comes a year after a similar Legionnaires’ summer outbreak in Harlem that killed seven people and sickened more than 100.

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