NEW YORK – A fourth person has died in connection with a Legionnaires’ disease outbreak in New York City, health officials disclosed Thursday as they revealed that some cooling towers that tested positive for the bacteria are in city-run buildings.

The outbreak in Central Harlem has sickened dozens since it began in late July. Seventeen people were hospitalized as of Thursday, according to the health department.

The bacteria that causes Legionnaires’ disease had been discovered in 12 cooling towers on 10 buildings, including a city-run hospital and sexual health clinic, health officials said. Remediation efforts have been completed on 11 of the cooling towers, with the final tower’s remediation required to be completed Friday.

Legionnaires’ disease is a type of pneumonia that is caused by Legionella bacteria, which grow in warm water and spread through building water systems. The city’s outbreak has been linked to cooling towers, which use water and a fan to cool buildings.

People usually develop symptoms — a cough, fever, headaches, muscle aches and shortness of breath — between two days to two weeks after exposure to the bacteria, according to the U.S. Centers for Disease Control and Prevention.

Dr. Michelle Morse, the city’s acting health commissioner, said new cases in the Central Harlem outbreak have begun to decline “which indicates that the sources of the bacteria have been contained.” She urged people who live or work in the area to contact a health care provider if they develop flu-like symptoms.