Legionellosis 101

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

How does Legionella bacteria grow?

The bacteria naturally grow in freshwater, like lakes and streams. Once the water enters building water systems, the bacteria can grow and multiply in the following conditions:

• Warm water temperatures between 77 °F to 113 °F
• Stagnant or low-flow water conditions
• Not enough disinfectants in the water system

How does Legionella spread?

People can get sick when they breathe in tiny water droplets that are contaminated with Legionella bacteria. Legionella does not spread from drinking contaminated water, only by breathing it in.

Where are you most likely to be exposed to the bacteria?

Common places to be exposed to Legionella bacteria are systems or fixtures that aerosolize water into tiny droplets, which can include:

• Showerheads and sink faucets
• Hot tubs
• Decorative fountains and water features
• Large, complex plumbing systems
• Cooling towers
• Medical devices with a water reservoir

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

Legionnaires’ disease

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

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.

SNHD_EHoutbreaksupport@snhd.org
(702) 759-1504

Nevada Relay “Dial 711” (TTY)
After Hours & Public Health Emergencies
(702) 759-1000