Story highlights Two people have died in the outbreak

There have been 31 cases since mid-July

(CNN) Two people have died in a Legionnaires' disease outbreak in New York. Thirty-one cases of the flu-like disease have been reported since mid-July in the South Bronx, the New York City Department of Health and Mental Hygiene said.

Legionnaires' disease is a respiratory bacterial infection usually spread through mist that comes from a water source, such as cooling towers, air conditioning or showers. It is not transmitted person to person. Symptoms of the disease include fever, chills and a cough. Most people recover, but between 5% to 30% of those who get the disease die, according to the U.S. Centers for Disease Control.

"We are conducting a swift investigation to determine the source of the outbreak and prevent future cases. I urge anyone with symptoms to seek medical attention right away," said Dr. Mary Bassett, commissioner of the New York City health department.

The health department's probe includes testing water from potential sources in the area.

"The New York City water supply does not pose a risk, so people should continue to feel confident in drinking tap water to stay cool during this period of hot weather," said Bassett.

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