Legionellosis is an infection caused by Legionella bacteria. There are two types of legionellosis: Legionnaires’ disease and Pontiac fever. Legionnaires’ disease is a serious lung infection, or pneumonia. Pontiac fever is a more mild illness. People can get sick with legionellosis when they breathe in water droplets that contain the bacteria.

The number and rate of reported legionellosis cases has been increasing.

Number of Legionellosis state cases reported
Rate of Legionellosis cases

Legionella bacteria grow naturally in water and can grow and spread in a water system if the system is not property maintained. Outbreaks of legionellosis are most commonly associated with large or complex water systems (e.g., hospitals, long-term care facilities, hotels).

Investigation Spotlight:

In 2017, public health officials investigated a large outbreak of legionellosis linked to a hotel aquatics facility in western Tennessee. To learn more about this investigation, visit: https://www.cdc.gov/mmwr/volumes/67/wr/mm6702a5.htm.

Legionella Fact Sheets:

Vacation Rentals

Legionella Webinar Series:

The Tennessee Hospital Association, Tennessee Healthcare Engineering Association, and Tennessee Department of Health developed the "Legionella Webinar Series" to raise awareness about Legionnaire's disease and the importance of prevention through water management programs. Recorded webinars and presentations can be found below.

Introduction to Healthcare-Associated Legionellosis

Water Management Programs

Developing a Water Management Program

Healthcare Experience with Water Management Programs

What to Expect in an Outbreak

Review Resources and Healthcare Implications

Useful Links:

SharePoint Toolkit (for public health)

TDH Reportable Disease Information: https://www.tn.gov/health/cedep/reportable-diseases/legionellosis.html

CDC Information: https://www.cdc.gov/legionella/index.html