A third person has died from the Legionnaires’ disease cluster on the Upper East Side, health officials announced, but the recent decline in new cases suggests that the source of the deadly outbreak has likely been eliminated.

“It is with great sadness that I report a third person has died in connection with the Legionnaires’ disease community cluster on the Upper East Side. Our hearts are with their family and friends as they mourn their loss,” NYC Health Commissioner Dr. Alister F. Martin said Sunday.

The latest death marks the third day in a row that health officials have announced the bacterial disease claimed a life. The first death connected to the outbreak in the posh Manhattan neighborhood was announced on Friday. 

None of those killed by the illness have been identified. 

The Spence School was one of many locations where the deadly Legionnaires’ disease was detected. Matthew McDermott for NY Post

The latest Legionnaires’ disease outbreak to strike the city has seen at least 74 cases with over 59 people hospitalized.

Eight people remain in the hospital as of Sunday night, officials said.

An average of one new case had been reported per day between July 10 and July 17, a sharp decline from the first week of July where an average of over eight new cases were being reported daily, officials said.

Health officials have also not identified anyone with new symptoms for more than a week — which means the city likely terminated the source of the outbreak, Martin said. 

All victims of the outbreak have been on the Upper East Side from the cluster in the Carnegie Hill and Yorkville neighborhoods.

The disease stems from Legionella bacteria that has been found in 76 cooling towers across Upper East Side neighborhoods. Getty Images

All victims of the outbreak have been on the Upper East Side from the cluster in the Carnegie Hill and Yorkville neighborhoods. Matthew McDermott for NY Post

The disease, which stems from Legionella bacteria that has been found in 76 cooling towers across Upper East Side neighborhoods and one on the Upper West Side, is a deadly type of pneumonia that can be treated with antibiotics if caught early.

City officials ordered all buildings that returned positive screening results to clean and disinfect their systems as part of the investigation.

All required remediations were completed by July 16.

“We will continue inspecting every cooling tower that tested positive and will hold accountable any owner who fails to comply with our public health laws,” Martin added.

This year’s outbreak comes after over 250 cooling towers around the Big Apple were cited for issues relating to Legionella testing since last year — and more than half of those were in Manhattan.

Last year, there was an outbreak of the disease in Harlem that killed five people and sickened 114.