Earlier this week, New York City Major Bill de Blasio announced that a recent outbreak of Legionnaires’ disease has resulted in 81 sick, seven cases even resulted in death. The outbreak began in July and was believed to have originated in the water from cooling towers, say Yahoo Health reports.

The disease — which is a form of pneumonia, caused by the water-dwelling bacteria Legionella — is not transmitted from person to person. Instead, it is acquired by breathing in infected water vapors and mists in the air. It can show up in air conditioners, showers, faucets, hot tubs, cooling towers, large plumbing systems and even mall water fountains.  Officials say people are more in danger of contracting the disease from direct contact with the bacteria when the concentration is high enough to actually make them sick.

This is the second major outbreak of the disease in the U.S. in a month. A Super 8 motel in Washington state voluntarily closed in early July after three cases of Legionnaires’ disease were linked to the establishment, the Associated Press reported.

Also known as Legionellosis, Legionnaires’ disease results in an estimated 18,000 hospitalizations in the U.S. each year, according to the Centers for Disease Control and Prevention, but experts say the number of people infected by the disease is much higher. Outbreaks are also more common in the summer and early fall, say officials, likely because people are more commonly exposed to sources where bacteria grows.

But not everyone who comes into contact with the bacteria actually develops Legionnaires’ disease. People who are older, smokers, and those with weakened immune systems are more at risk, according to the CDC.

Symptoms are similar to pneumonia’s and can include fever, chills, muscle aches, and cough. Some people may also experience headaches, fatigue, a loss of appetite, confusion, or diarrhea.

Experts say Legionnaries’ disease is something we should always be aware of. It won’t go away because it is a natural bacteria found in the water.

To read this full report, click here.

For information on disease recognition, investigation procedures to identify probable water sources, and control strategies, visit the OSHA website.