New York City officials are investigating an outbreak of Legionnaires’ disease in the South Bronx, after thedeath toll rose on Friday.

A third person was confirmed dead from the disease, according to NBC, citing local officials. More than 50 others have contracted the severe form of pneumonia.

The infection causes inflammation in the lungs and is known to be especially lethal, particularly in older adults, smokers and people with weakened immune systems.

3rd death in NYC #Legionnaires outbreak in person with “underlying medical issues.” Total number of cases is 57.

— Jarrett Murphy (@jarrettmurphy) July 31, 2015

The New York City Health department said Friday that 57 cases were reported in the Bronx area since July 10.

The health department has not released detailed information on those who died from the disease, but two of them were people in their 50s.

Legionnaires’ disease is caused by exposure to the bacteria Legionella. People typically become infected with the bacteria from contaminated cooling towers, hot tubs, showers and faucets or drinking water.

About 2,200 Legionnaires’ illnesses have been reported nationwide since Jan. 1, including more than 100 in New York City. City Health Commissioner Dr. Mary Bassett said earlier this week that the South Bronx cases represent an “unusual increase.”

Health experts are testing water from cooling towers and other potential sources to determine the cause.

New Yorkers with such symptoms as fever, cough, chills and muscle aches are advised to seek medical attention promptly.

Addition reporting by The Associated Press.
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