Management of Legionella in Water Systems

Legionnaires' disease, a pneumonia caused by the Legionella bacterium, is the leading cause of reported waterborne disease outbreaks in the United States.

Legionella occur naturally in water from many different environmental sources, but grow rapidly in the warm, stagnant conditions that can be found in engineered water systems such as cooling towers, building plumbing, and hot tubs.

Humans are primarily exposed to Legionella through inhalation of contaminated aerosols into the respiratory system.

Legionnaires' disease can be fatal, with between 3 and 33 percent of Legionella infections leading to death, and studies show the incidence of Legionnaires' disease in the United States increased five-fold from 2000 to 2017. Management of Legionella in Water Systems reviews the state of science on Legionella contamination of water systems, specifically the ecology and diagnosis.

This report explores the process of transmission via water systems, quantification, prevention and control, and policy and training issues that affect the incidence of Legionnaires' disease.

It also analyzes existing knowledge gaps and recommends research priorities moving forward. Table of ContentsFront MatterSummary1 Introduction2 Diagnosis, Ecology, and Exposure Pathways3 Quantification of Legionnaires' Disease and Legionella4 Strategies for Legionella Control and Their Application inBuilding Water Systems5 Regulations and Guidelines on Legionella Control in Water SystemsAcronymsAppendix: Biographical Sketches of Committee Members and Staff