Legionnaire's Disease

What Is It?
Legionnaire's Disease (legionellosis) is a fairly common and acute bacterial disease which is not new -- nor is it confined to any particular area. The earliest documented case occurred in 1947, and the earliest outbreak was recorded in 1957. Most people remember that it got its name from an outbreak of pneumonia that happened in Philadelphia during 1976 in which American Legion members became ill.

How Common Is It?
Each year, Ohio records approximately 150 cases of the disease. In the United States, between 10,000 and 15,000 people get Legionnaire's Disease in any given year -- and there are probably many more who are exposed but either have mild symptoms or none at all. Cases have been identified throughout North America, as well as Australia, Africa, South America and Europe. Although cases occur throughout the year, both sporadic cases and outbreaks are more common in summer and autumn.

How Many People Get Exposed?
At any point in time, up to 20 percent of the population will test positive for Legionnaire's antibodies. Most of these people will have had either very mild symptoms or no symptoms at all.

How Do People Catch It?
Legionnaire's Disease is NOT transmitted from person to person. Exposure is believed to take place in the air, probably because of bacteria in some type of water system: hot water systems, air conditioning cooling towers, condensers, humidifiers, whirlpool spas, respiratory therapy devices, and decorative fountains. The bacteria has also been found in hot and cold water taps and showers, hot tubs, and from creeks and ponds and the soil from their banks.

Why Do Some People Get Sick And Others Do Not?
Illness occurs most frequently in people who are older (usually over age 50), and especially in people who smoke and in those who have another illness such as diabetes, chronic lung disease, renal disease or cancer. People whose immune systems are compromised (down) because of these or other conditions would be most at risk.

How Are Patients Handled?
The case is reported to local health officials but isolation, concurrent disinfection or quarantine are NOT necessary. Health officials will most likely check to see if the case is isolated -- and most cases are not part of a larger problem -- or part of a possible outbreak.

How Is Legionnaire's Disease Treated?
The treatment of choice is an antibiotic, usually erythromycin.

What Are The Symptoms?
Legionnaire's Disease is characterized by an acute pneumonia. Other symptoms include a lack of appetite, fatigue, muscle aches and headache. Within a day, there is usually a rapidly rising fever and chills, with the fever reaching between 102 and 105 degrees. A non-productive cough, abdominal pain and diarrhea are also common.

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Last Updated: 06/13/2001