Legionnaires' Disease

Doctor and nurse in uniform, Hospital and Healthcare staff, Professional medical care provider.

What is Legionellosis?

Legionellosis is a bacterial disease of the lungs caused by Legionella pneumophila. The disease can range from a mild respiratory illness to severe pneumonia and death. The most common form of Legionellosis is known as "Legionnaires' disease," named after an outbreak in 1976 when many people who attended an American Legion conference in Philadelphia became ill.

Resources
Publications

Expand All Collapse All

Legionella bacteria are widely distributed, and normally grow best in warm water environments. They have been found in creeks and ponds, water taps (primarily hot water taps), hot water tanks, cooling towers and evaporative condensers, whirlpool spas, and decorative fountains.

Most people contract the disease by inhaling mist or vapor from a water source contaminated with the bacteria. In some cases, the disease may be transmitted by other ways, such as aspirating contaminated water. The disease is not contracted by drinking contaminated water, and person-to-person spread of Legionellosis does not occur.

Outbreaks occur following the exposure of many individuals to a common source of the bacteria in the environment. When a single case occurs, it is extremely difficult to pinpoint a source. Environmental testing is recommended only when multiple cases have the same potential exposure.

Because man-made water systems are the most likely source of Legionella, appropriate maintenance is very important. Water temperatures can be raised to reduce transmission, and chemical treatments or biocides can be administered to water systems to inhibit growth of bacteria.

The incubation period, the time between exposure and onset of illness, is up to 12 days.
Legionellosis usually begins with symptoms like high fever (102 degrees F - 105 degrees F), chills, muscle pain, and headache. Other symptoms may include cough (which may be dry or productive), shortness of breath, chest pain, or even gastrointestinal symptoms like diarrhea. Legionnaires' disease cannot be distinguished from other causes of pneumonia based on symptoms alone. Laboratory testing is required to establish this diagnosis.

People of any age may get Legionnaires' disease, but the disease most often affects persons older than 50. The disease is rare in people younger than 20 years of age. People at high-risk of acquiring the disease include current and former smokers, persons with chronic lung disease like emphysema or COPD, or those with compromised immunity (like patients who receive corticosteroids or have had an organ transplant). People with underlying illnesses, such as cancer, kidney disease, diabetes, or AIDS are also at higher risk.

Legionella Management for Health Care Facilities

***IDPH and Illinois Department of Veterans’ Affairs continue to collaborate with the Centers for Disease Control and Prevention (CDC) to help ensure the safety and well-being of residents and staff at the Illinois Veterans’ Home in Quincy after outbreaks of Legionnaires’ disease since 2015. IDPH requested epidemiological assistance from the CDC, who sent a team of environmental and infectious disease specialists to Quincy. The CDC released three reports on the outbreaks (see on the right menu under Publications).

***In the 2017 report, sections have been redacted to protect patient confidentiality.***

Legionnaires' Disease

What is Legionellosis?

INFORMATION FOR

RESOURCES

QUICKLINKS

Legionnaires' Disease

What is Legionellosis?

How common is Legionellosis?

How common is Legionellosis?

How are people infected with Legionella?

What are the usual symptoms of Legionellosis?

Who is most at risk for Legionellosis?

How is Legionellosis diagnosed?

What is the treatment for Legionellosis?

How are cases of Legionellosis reported?

Footer

INFORMATION FOR

RESOURCES

QUICKLINKS