So far the city says nine people have been diagnosed and hospitalized.
As CBS2's Lisa Rozner reports, Department of Health workers are sampling and testing water from cooling towers in Central Harlem and bordering neighborhoods - the zip codes 10037 and 10039.
That's because most cases of Legionnaires' disease can be traced to plumbing system.
The disease is a type of pneumonia, caused by the bacteria legionella, which grows in warm water.
"It's very concerning for the neighborhood," said Gloria Ortiz.
"I'm afraid. I really am. But I always drink bottled water, and I boil my water when I was my dishes anyway, so now I'm going to be extra cautious," said Wendy Richardson.
"I'm very worried, yes," said Harlem resident Jovon Turner.
The Health Department says the cases have occurred with the last two weeks, and most people are over the age of 50. Health officials say it is not contagious, and can be treated with antibiotics when caught early.
"It said it's curable if it's caught on time, so I hope it doesn't spread," said Eddie White.
New Yorkers with flu-like symptoms, cough, fever or difficulty breathing should call a doctor immediately.
Due to the ongoing spread of COVID-19, the city says individuals seeking care should be tested for COVID and evaluated for Legionnaires'.
"Right now, with this pandemic, it's very, very hard," said Moussa Komate.
"We just have to do our best to keep ourselves healthy. If we can afford bottled water, that's the best we can do," said Vanessa Cherry
The health commissioner says most people exposed to legionella don't get sick. Those who are at higher risk include people over the age of 50, as well as those who smoke and have chronic lung conditions. The biggest danger is breathing in the vapor from warm water.
Residents' message to the city about the plumbing?
"Where do cleaning come up, how they going to go about cleaning it and who they going to let know how they clean it?" said Lester Jordan.
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