Health Topics for Infectious Diseases

Department of Internal Medicine: Infectious Diseases

Department of Internal Medicine: Travel Medicine

Legionnaire's disease

Legionnaires' disease is an inflammation and infection of the lungs caused by a bacteria called legionella. The disease got its name in 1976, when a group of men from the American Legion became ill at a convention. The cause was found to a bacteria spread by the air conditioning system at the hotel.

The bacteria grows easily in warm, stagnant water, such as that found in some plumbing systems, hot water tanks, whirlpool baths or spas, shower heads and faucets, and cooling towers of large air- conditioning systems. There is no indication that bacteria are spread from auto air conditioners or household window air- conditioning units. Although rare, recent studies have shown the bacteria is also found in potting soil. Legionnaires' does not appear to be spread from person to person.

When small particles of contaminated water reach the lungs, it can cause 2 distinct illnesses:

• Legionnaires' disease, a more severe infection, which includes pneumonia and
• Pontiac fever, a mild "flu-like" illness without respiratory symptoms or pneumonia

Some people who are infected with the bacteria have no symptoms at all. Others may have severe pneumonia leading to death. The milder form, Pontiac fever, causes muscle aches and fever, but no respiratory symptoms. Legionnaires' disease produces muscle aches, tiredness, abdominal pain, loss of appetite, headache, cough, and a high fever of 104 to 105 degrees Fahrenheit (40 to 40.6 degrees Centigrade) with shaking chills. Occasionally confusion, diarrhea, chest pain, or kidney problems may also occur. The time from exposure to the first symptoms for Legionnaires' can be from 2 to 10 days. For Pontiac fever it is a few hours to a few days.

Legionnaires' disease can affect people of any age, but is usually found in middle-aged and older persons. Those with the highest risk are those who:

• are elderly
• have chronic diseases, such as diabetes, cancer, chronic lung diseases, kidney failure, HIV/AIDS
• smoke cigarettes or
• have suppressed immune systems

Legionnaires' is treated with antibiotics, such as Erythromycin. Other drugs are available for patients who cannot take Erythromycin. In severe cases, a second drug, Rifampin, may also be used. Patients usually recover in 1 to 2 weeks. Pontiac fever requires no specific treatment and people usually feel better in 2 to 5 days.

Thorough maintenance and treatment of air and water delivery systems can reduce outbreaks of Legionnaires' disease.

Last Reviewed 2005

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIL File Infe4733.RF2 VRS# 4733 Data Version 7.0 Copyright 1999-2000, 2003 McKesson Health Solutions LLC. All rights reserved.