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Legionnaires' Disease and Pontiac Fever

Topic Overview

What are Legionnaires' disease and Pontiac fever?

Legionnaires' disease is a type of pneumonia . It is caused by bacteria called Legionella pneumophila. The bacteria got its name in 1976, when a group of people attending an American Legion convention became infected. Although it was present before 1976, Legionnaires' disease is being diagnosed more often now as doctors look for Legionella bacteria in people who have pneumonia. You can get Legionnaire's disease at any time of the year, but more cases are usually found in the summer and early fall. While Legionnaires' disease can be very serious, most cases can be treated successfully.

The Legionella pneumophila bacteria can also cause a less severe, flu-like condition known as Pontiac fever.

How do you get these conditions?

People usually get Legionnaires' disease or Pontiac fever when they breathe in a mist or vapor (small droplets of water in the air) that contains the bacteria. One example might be from breathing in the steam from a whirlpool spa that has not been properly cleaned and disinfected. Other sources include fountains and water sources in hotels, cruise ships, nursing homes, and hospitals.

These diseases aren't contagious. The bacteria are not spread from one person to another person. You can get the diseases again if you are exposed to the bacteria again.

Legionnaires' disease typically affects people older than 45, especially if they smoke or have a long-term lung disease such as asthma . 1 People with a weak immune system are also more likely to get the condition. Despite its being named after infecting a large group of people, Legionnaires' disease usually occurs in single cases, not in large groups at one time (an outbreak).

Pontiac fever usually occurs in otherwise healthy people.

What are the symptoms?

The most common symptoms of Legionnaires' disease include:

  • Cough.
  • High fever.
  • Chills.

Less common symptoms range from muscle aches and headaches to abdominal (belly) pain, shortness of breath, and chest pain.

Legionnaire's disease symptoms usually appear 2 days to 2 weeks after a person is exposed to the bacteria. Symptoms can range from mild to severe.

Pontiac fever symptoms include fever and muscle aches. Symptoms usually appear 1 to 2 days after a person is exposed to the bacteria. They usually go away without treatment in a few days.

How are the conditions diagnosed?

Your doctor can diagnose both Legionnaires' disease and Pontiac fever by asking about your past health and by doing a physical exam. If your doctor thinks you have Legionnaires' disease, he or she will ask about your working conditions, if you have been around any possible source like fountains or hot tubs, and if you have traveled within the past 2 weeks. The doctor will also do tests. The tests may include a urine test or looking at mucus from your lungs.

How are they treated?

Most cases of Legionnaires' disease can be treated successfully with antibiotics . Treatment usually lasts at least 5 days.

Fever tends to improve or go away within the first few days. A cough may take longer to disappear. But in general you should start to feel better within the first few days of treatment. Complete recovery can take from 2 to 4 months.

Pontiac fever will go away without treatment. To reduce fever and muscle aches, drink plenty of fluids and consider taking over-the-counter pain relievers like acetaminophen (Tylenol, for example) or nonsteroidal anti-inflammatory drugs (NSAIDs). 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 . Be safe with medicines. Read and follow all instructions on the label.

What should you do if you think you were exposed to the bacteria?

Most people who are exposed to the bacteria don't become ill. But if you believe you were exposed, talk to your doctor or local health department. Be sure to tell them where you think you were exposed and if you have traveled in the last 2 weeks. This information will help them correctly diagnose and treat the disease, locate the source of the bacteria, and prevent others from being exposed to it.

Related Information

References

Citations

  1. Neil K, Berkelman R (2008). Increasing incidence of legionellosis in the United States, 1990–2005: Changing epidemiologic trends. Clinical Infectious Diseases, 47(5): 591–599.

Other Works Consulted

  • CDC Legionellosis Resource Site (2011). Patient Facts: Learn More About Legionnaires’ Disease. Available online: http://www.cdc.gov/legionella/patient_facts.htm.
  • Edelstein PH, Cianciotto NP (2010). Legionella. In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., vol. 2, pp. 2969–2984. Philadelphia: Churchill Livingstone Elsevier.
  • Infection Control Services (2007). Legionnaires' disease. Available online: http://www.infectioncontrolservices.co.uk/legionnaires_disease.htm.
  • Neil K, Berkelman R (2008). Increasing incidence of legionellosis in the United States, 1990–2005: Changing epidemiologic trends. Clinical Infectious Diseases, 47(5): 591–599.
  • Oklahoma State Department of Health (2005). Public Health Fact Sheet: Pontiac Fever. Available online: http://www.ok.gov/health/documents/Pontiac%20Fever.2005.pdf.

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology
Current as of June 4, 2014

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