Legionnaires' disease is a serious, sometimes fatal form of pneumonia. Pontiac Fever is a less serious influenza-like infection. Together they are the two most common forms of legionellosis, which is caused by Legionella bacteria. The Legionella bacteria are found naturally in the environment, usually in water. People get Legionnaires' disease when they breathe in a mist or vapor (small droplets of water in the air) containing the bacteria. The bacterium is not spread from person to person. According to the Centers for Disease Control and Prevention (CDC), the rate of the spread of legionellosis has nearly tripled since the year 2000. The CDC also reports that a study of reported cases indicated a death rate of 40 percent for cases acquired during a hospital stay, and a death rate of 20 percent for people who acquired the infection elsewhere.
Top Tips for Camps
- Maintain your pools, plumbing systems, drinking water systems, and hot tubs properly. Because high water temperatures make it hard to maintain the disinfectant levels needed to kill germs like Legionella, make sure that your pools, hot tubs, plumbing systems, decorative fountains, and drinking water systems are maintained with the right disinfectant and pH levels. Guidelines for appropriate water temperatures and chemical treatment of water for legionellosis prevention can be found in ASHRAE Guideline 12-2000. 
- Ensure that your health and medical staff are knowledgeable. The CDC reports that it is difficult to distinguish this disease from other forms of pneumonia; therefore, many cases go unreported. Make sure your health and medical support staff understand this infection. An excellent resource for clinicians can be found on the CDC Web site .
- Understand who is most at risk for infection. Most healthy individuals do not become infected with Legionella bacteria after exposure. People at higher risk of getting sick are: older people (usually fifty years of age or older), current or former smokers, those with a chronic lung disease (like COPD or emphysema), those with a weak immune system from diseases like cancer, diabetes, or kidney failure, people who take drugs that suppress (weaken) the immune system (like after a transplant operation or chemotherapy).
The key to preventing legionellosis is maintenance of the water systems in which Legionella grow, including drinking water systems, hot tubs, decorative fountains, plumbing systems including showers and faucets, and cooling towers. Guidelines for appropriate water temperatures and chemical treatment of water for legionellosis prevention can be found in ASHRAE Guideline 12-2000 . There are no vaccines that can prevent legionellosis.
Signs and Symptoms
Legionnaires' disease can have symptoms similar to many other forms of pneumonia, so it can be hard to diagnose at first. Signs of Legionnaires' disease can include:
- Shortness of breath
- High fever
- Muscle aches
People get Legionnaires' disease when they breathe in a mist or vapor (small droplets of water in the air) containing the bacteria. These symptoms usually begin two to fourteen days after being exposed to the bacteria. The bacteria is not spread from person to person.
A milder infection, also caused by Legionella bacteria, is called Pontiac Fever. The symptoms of Pontiac fever are similar to those of Legionnaires’ disease and usually last for two to five days. Pontiac Fever is different from Legionnaires' disease because the patient does not have pneumonia. Symptoms go away on their own without treatment.
Legionnaires' disease requires treatment with antibiotics. Healthy people usually get better after being sick with Legionnaires’ disease, but hospitalization is often required. Pontiac Fever goes away without specific treatment. Antibiotics provide no benefit for a patient with Pontiac Fever.
- Centers for Disease Control and Prevention — Legionella 
- U.S. Department of Labor, Occupational Safety, & Health Administration — Legionnaires' Disease