Legionellosis is a disease caused by Legionella bacteria, which are naturally found in freshwater environments such as lakes, rivers, and streams. While the bacteria occur naturally in the environment, they can become a health concern when they grow and spread in poorly maintained building water systems.

About the Bacteria

Types of Legionellosis

Legionellosis is an infection caused by Legionella bacteria, and can occur in two forms:

• Legionnaires’ disease – severe form of pneumonia
• Pontiac fever – milder form of illness that shows flu-like symptoms

Types of Legionellosis

Legionnaires’ disease is a serious type of pneumonia caused by Legionella bacteria.

Legionnaires’ disease

Symptoms

Symptoms of Legionnaires’ disease include:

• Cough
• Fever
• Headaches
• Muscle aches
• Shortness of breath
• Other symptoms can also occur such as confusion, diarrhea, or nausea

These symptoms usually develop between 2 to 14 days after being exposed to Legionella bacteria, but it can take longer.

 High Risk Groups

Individuals that are at increased risk for developing Legionnaires’ disease include:

• Elderly people aged 50 and older
• Current and former smokers
• People with chronic lung disease (such as emphysema, chronic obstructive pulmonary disease, etc.)
• People with compromised immune systems from underlying health conditions (including HIV, cancer, diabetes, kidney disease, chemotherapy, organ transplant, etc.)

Pontiac fever

Legionella infection can also result in a milder form of illness called Pontiac fever, which can affect healthy people of any age when exposed to the bacteria. People that are ill with Pontiac fever usually get better without any treatment.

Symptoms

Symptoms of Pontiac fever include:

• Fever
• Muscle aches
• Headaches

These symptoms usually develop within a few hours and up to 3 days after being exposed to Legionella bacteria.