Lung Disease & Respiratory Health Center

Legionnaires' disease and Pontiac fever

What are Legionnaires' disease and Pontiac fever?

Legionnaires' disease is a type of pneumonia. This type of pneumonia is caused by bacteria called Legionella pneumophila. The bacteria can also cause a less severe, more flu-like condition known as Pontiac fever. The diseases caused by Legionella pneumophila are also called legionellosis.

Legionnaires' disease generally affects people older than 50, especially if they smoke or have a long-term lung disease, such as asthma. People with a weak immune system are more likely to get the condition than others are. Legionnaires' disease usually occurs in single cases, not in large groups of people at one time (an outbreak). When outbreaks do occur, it is usually in the summer or early fall. Single cases can occur year-round.

Pontiac fever usually occurs in otherwise healthy people.

How do you get the conditions?

You develop either condition from breathing in the bacteria from contaminated water sources, such as air-conditioning cooling towers, plumbing systems, hot-water tanks, and spas. These sources often have warm, stagnant water that allows bacteria to grow and increases your risk of getting either condition. People who work near natural bodies of water do not appear to be at increased risk for either condition.

What are the symptoms?

The symptoms of Legionnaires' disease include fever, chills, and a cough, which may produce mucus. You may also experience muscle aches, headache, tiredness, loss of appetite, and diarrhea. Not everyone has the same symptoms, which range from mild to severe.

The symptoms of Pontiac fever are fever and muscle aches. The symptoms generally go away in 2 to 5 days without treatment.

How are the conditions diagnosed?

Your doctor can diagnose both Legionnaires' disease and Pontiac fever by asking about your medical history and doing a physical exam. If your doctor thinks you have Legionnaires' disease, he or she will ask about your working conditions and do tests. Testing may include a urine test or looking at mucus from your lungs.

How are they treated?

Doctors treat Legionnaires' disease with antibiotics.

Pontiac fever requires no specific treatment, although you may use home treatment to reduce pain and fever. This includes taking nonprescription pain relievers, such as acetaminophen or nonsteroidal anti-inflammatory drugs (NSAIDs). Examples of acetaminophen include Panadol and Tylenol. NSAIDS include ibuprofen (such as Advil and Motrin), naproxen (such as Aleve), and aspirin. Do not give aspirin to anyone younger than 20 because of the risk of Reye syndrome. You should also drink plenty of fluids.