A third person has died of the Legionnaires’ disease outbreak in Harlem that has sickened close to 70 people, Mayor Eric Adams said Wednesday — confirming that the source appears to be local cooling towers.

The deadly cluster of the pneumonia-like illness, first detected on July 25, has spread across five zip codes in Upper Manhattan and sickened at least 67 people, the mayor confirmed.

None of the three people killed has been publicly identified.

“We believe [the outbreak] is located in Central Harlem coming from the cooling towers,” the mayor said in a video statement Wednesday morning. 

“We’re asking you if you have flu-like symptoms and you’re in that area to please seek medical attention,” he added.

So far, the disease has been detected in zip codes 10027, 10030, 10035, 10037 and 10039, as well as in neighboring communities.

The latest numbers show a worrying jump from the last update provided on Monday, when two deaths and 58 cases were reported.

The rare disease, while deadly, is easily treatable if caught early, city health officials said.

Although potentially fatal if not treated in time, Legionnaires’ disease does not spread from person to person and can be treated easily with antibiotics if diagnosed early, the health department said.

The disease is typically transferred through water supplies contaminated with Legionella bacteria that can appear in plumbing systems and find favorable conditions in cooling towers, whirlpool spas, hot tubs, humidifiers and condensers in large air conditioning systems.

The health department has found the bacteria in 11 cooling towers.

“If we find any source of Legionnaires’ disease, we are instructing building owners to do a full remediation within 24 hours,” Adams said.

Between 200 and 700 of 8.5 million New Yorkers are diagnosed with Legionnaires’ disease each year, according to the health department.

The last major outbreak happened in summer 2022, when at least five people died at a Manhattan nursing home.