What is Legionnaires’ disease? FAQs about the severe form of pneumonia

What are the signs and symptoms of pneumonia?

This story has been updated.

At least a dozen guests at the Sheraton Atlanta recently tested positive for Legionnaires' disease, prompting the downtown hotel to temporarily close its doors. The facility was cleared to reopen after an inspection of by the Fulton County Board of Health on Thursday. The Georgia Department of Public Health announced another 63 cases are "probable."

» RELATED: Authorities confirm source of Legionnaires' at Sheraton Atlanta

Here’s what you should know about the illness:

According to the Atlanta-based Centers for Disease Control and Prevention, Legionnaires' is a severe form of lung infection (or pneumonia) caused by thin, microscopic Legionella bacteria, which naturally exist in freshwater but can grow in man-made settings if the water isn't properly maintained. Each year, 8,000 to 18,000 people in the United States are hospitalized with Legionnaires'.

How does it spread?

Legionella can become potentially dangerous when they grow in ill-maintained man-made settings such as hot tubs, showers with potable water, cooling water systems or decorative fountains. The bacteria doesn't generally spread from people to people. Instead, it is spread through small droplets of water which evaporate into the air as people breathe them in. The CDC notes that in rare cases, someone may even breathe in Legionella while drinking water and it "goes down the wrong pipe."

What are the signs and symptoms?

Signs and symptoms of Legionnaires’ include cough, muscle aches, shortness of breath, headache and fever. Individuals older than age 50, those who smoke or used to smoke and anyone with a chronic lung disease or weakened immune system may be at increased risk for the disease.

What do I do if I think I have Legionnaires’?

If you notice any of the aforementioned pneumonia symptoms and believe you may have been exposed to Legionella, experts recommend you see a doctor immediately. When you meet your doctor, make sure you mention any recent hot tub use, whether you've stayed away from home recently or visited the hospital in the last two weeks.

How does diagnosis and treatment work?

To test for Legionnaires’, your doctor will likely perform a chest x-ray, require a urine test and a lab test that involves taking a phlegm sample.

Antibiotics are typically prescribed if you test positive for the disease, which kill the Legionella bacteria inside your body.

While most cases of Legionnaires’ can be successfully treated, about one in 10 people who get sick with the illness will die due to complications, usually due to lung failure.

The CDC has a great toolkit available regarding Legionnaires’ protection. Some big pointers:

  • Make sure the hot tub or spa you're using is properly maintained. You can be infected with Legionella just by breathing in steam or mist from a contaminated hot tub. Maintenance involves regularly checking your hot tub's disinfectant and pH levels.
  • If you're about to use a hot tub and want to make sure it's safe, purchase pool test strips from your local home improvement store for chlorine, bromine and pH levels. According to the CDC, appropriate levels include: 2-4 parts per million chlorine, 4-6 ppm bromine and 7.2-7.8 pH levels. If you do notice improper readings, inform the hot tub operator or owner immediately.
  • No test strips in hand? If you're not in charge of maintaining the tub, ask for the most recent health inspection. Your operator should also be able to answer how often disinfectant and pH levels are checked.

For more prevention tips, download this toolkit.