More than forty years ago, a mysterious illness made headlines in Philadelphia when 182 people became ill and 29 people died. This yet to be named disease was found to be linked to Legionella bacteria and was classified as a serious type of pneumonia. Eventually, this illness would become known as Legionnaires' disease.

Although it is considered a rare disease, Legionnaires' disease is a growing health concern. Since 2000, the number of people developing this disease has been on the rise. In 2018, the Centers for Disease Control and Prevention (CDC) reported that about 10,000 people in the United States were diagnosed with Legionnaires' disease. 

Here are five things you need to know about Legionnaires’ disease to keep you and your family safe: 

1. The Legionella bacteria that causes Legionnaires’ disease is naturally found in freshwater. The CDC has reviewed Legionnaires’ disease outbreaks and found that certain types of buildings and water sources are more likely to be associated with this disease. The most common places where people are exposed to the bacteria are hotels, vacation rental properties, long-term care facilities and hospitals. In these types of buildings, the most likely sources for spreading water droplets contaminated with the bacteria include showers and faucets, cooling towers (parts of large, centralized air conditioning units), hot tubs and decorative fountains. Cruise ships are another place where Legionnaires' disease outbreaks can happen. The CDC recommends building owners and managers use Legionella water management programs to reduce the risk of Legionnaires' disease.

2. Anyone can get Legionnaires’ disease, but certain people are at higher risk. Legionnaires’ disease is not spread from person to person. To get sick, most people breathe small droplets of water containing the bacteria into their lungs. In rare cases, people can get sick after contaminated drinking water is swallowed “down the wrong pipe” into the lungs. 

People who are at increased risk include:

  • Individuals 50 years or older
  • Individuals who smoke or have a history of smoking
  • Individuals who have a chronic lung disease, such as or chronic obstructive pulmonary disease (COPD)
  • Individuals who have an underlying medical condition like diabetes, cancer, kidney failure or liver failure

3. See a doctor right away if you develop pneumonia symptoms. Signs and symptoms of Legionnaires’ disease are similar to other types of pneumonia. They include cough, muscle aches, fever, shortness of breath and headache. When you see the doctor, mention any possible exposures to Legionella. Be sure to mention if you used a hot tub, spent any nights away from home, or stayed in a hospital in the last two weeks.

4. Get treated as soon as possible. Most people with Legionnaires' disease will need hospital care but will fully recover with treatment. The sooner you get treatment, the less likely you are to develop serious complications. The most common treatment is antibiotics. Individuals who have a weakened immune system need to be especially vigilant as about one in ten who get this disease will die due to complications from their illness.

5. The best way to guard against the disease is to prevent it. If you are unsure of how well maintained a water source is, like a decorated fountain or hot tub, avoid it. Business and residential owners should make sure their water systems are well maintained. If you aren’t a manager, you can encourage owners and managers of the buildings where you live, work and get medical treatment to adopt a Legionella water management program.

Talk to your healthcare professional about your risk of getting sick and learn more at

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