Two people have died and at least 58 people have been diagnosed with Legionnaires’ disease in a cluster that broke out in the Harlem area of New York City last week, officials said on Monday.

The New York City Health Department had reported on Thursday that one person had died and 22 people were sick in the cluster.

“People living or working in the area with flu-like symptoms, such as cough, fever, chills, muscle aches, or difficulty breathing should contact a health care provider immediately,” the department said in a statement on Monday. “It is especially important for people at higher risk — including those ages 50 and older, cigarette smokers, and people with chronic lung disease or compromised immune systems — to get care if they have symptoms.”

Legionnaires’ disease is a type of pneumonia that is caused by the bacteria Legionella, which grows in warm water, health officials said, and people can get Legionnaires’ disease by breathing in water vapor that contains Legionella bacteria.

“Anyone in these zip codes with flu-like symptoms should contact a health care provider as soon as possible,” said Acting Health Commissioner Dr. Michelle Morse. “Legionnaires’ disease can be effectively treated if diagnosed early, but New Yorkers at higher risk, like adults aged 50 and older and those who smoke or have chronic lung conditions, should be especially mindful of their symptoms and seek care as soon as symptoms begin.”

Legionnaires’ disease can be caused by plumbing systems where conditions are favorable for Legionella growth, such as cooling towers, whirlpool spas, hot tubs, humidifiers, hot water tanks and evaporative condensers of large air-conditioning systems, health officials said.

People can get Legionnaires’ disease by breathing in water vapor that contains Legionella bacteria, though officials reminded people that the disease cannot be transmitted from person to person and can be treated with antibiotics.

The respiratory disease takes its name from an outbreak at the Pennsylvania American Legion convention held at the Bellevue-Stratford Hotel in Philadelphia in July 1976 and the bacterium believed to be responsible is found in soil and grows in water, such as air-conditioning ducts, storage tanks and rivers.

No details about the two people who died have been released by officials as of Tuesday.