What is Legionnaires' disease? Atlanta hotel linked to outbreak of infection

An outbreak of Legionnaires’ disease at the Sheraton Atlanta during the busy summer travel season is a reminder dangerous germs can lurk in hotel hot tubs, showers and air-conditioning units.

Health officials in Georgia said this week there are now 11 lab-confirmed cases and 55 probable cases of the rare, but serious, lung infection linked to the outbreak. No one has died.

The local health department has asked people who stayed at or visited the hotel in downtown Atlanta between June 12 and July 15 to fill out surveys about what they did there and how they’ve been feeling, to find other potential patients and track down the cause of the outbreak.

The Sheraton voluntarily closed last month and remains closed. Hotel officials said it remains unknown if the source of the exposure was located within the property.

"Sheraton Atlanta management and ownership retained experts who implemented a plan for the requisite testing required by the state. Testing was completed this week, and the hotel has voluntarily moved ahead with remedial activities while it awaits results," said general manager Ken Peduzzi in a statement.

What is Legionnaires’ disease?

It’s a potentially life-threatening type of pneumonia caused by Legionella, a bacterium found naturally in lakes and streams, but which can also grow in large human-made water systems found in hotels, hospitals and cruise ships, according to the Centers for Disease Control and Prevention.

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What is Legionnaires' disease? Atlanta hotel linked to outbreak of infection

If the water is not properly maintained, Legionella can multiply in wet places like shower heads, sink faucets, fountains, hot tubs that aren’t drained after each use and cooling towers. People can then breathe in mist that contains the germs and become ill.

It’s not spread person to person and is “very, very treatable when diagnosed early,” said NBC News medical contributor Dr. Natalie Azar.

Recent high-profile cases included outbreaks at Disneyland in 2017 and in the Bronx, New York, in 2015. There were about 7,500 cases of Legionnaires’ disease in the U.S. in 2017, with more illness reported in the summer and early fall than at other times of the year.

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What are the symptoms?

The warning signs begin two to 10 days after being exposed to the bacteria, but can take up to two weeks to show up. They include:

Who is most at risk?

Most healthy people exposed to the germs don’t get sick. The more vulnerable population includes:

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How is Legionnaires’ disease treated?

Once pneumonia is confirmed by a chest X-ray, doctors use a urine test or a phlegm test to check whether it was caused by Legionella. The treatment is a course of antibiotics for several weeks and hospital care, with most people making a full recovery. But 10% of patients with Legionnaires’ disease die from the infection, according to the CDC.

How is the disease prevented?

There are no vaccines that can prevent Legionnaires’ disease. The public essentially depends on building owners to take the proper measures to prevent the growth and spread of Legionella, such as regular inspections, cleaning and maintenance of water systems.

A. Pawlowski

A. Pawlowski is a TODAY senior contributing editor focusing on health news and features. Previously, she was a writer, producer and editor at CNN.