The Health Department says at least eight cases of Legionnaires' disease have been reported in southern Washington Heights and northern Hamilton Heights.
Officials said Wednesday that seven of the patients have been hospitalized in the past seven days and one person has been discharged. The health department said no one had died.
The disease comes from breathing in water vapor that has been contaminated with Legionella bacteria.
"When we see a cluster of cases which share a geography and nothing else that we can tell, we worry about cooling towers, so the department has already identified all the cooling towers that are registered with the city in this geography and has, in the course of today, tested all of these cooling towers," City Health Commissioner Dr. Mary Bassett said.
Adults who experience flu-like symptoms, fever, cough, or difficulty breathing should seek medical attention immediately.
The disease is not contagious and is easily treatable when caught early.