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.

Contents

• The National Academies of SCIENCES • ENGINEERING • MEDICINE
• COMMITTEE ON MANAGEMENT OF LEGIONELLA IN WATER SYSTEMS
• WATER SCIENCE AND TECHNOLOGY BOARD
• Preface
• Summary
  • ORGANIZATION OF THE REPORT
  • DIAGNOSIS, ECOLOGY, AND EXPOSURE PATHWAYS
  • QUANTIFICATION OF LEGIONELLA AND LEGIONNAIRES' DISEASE
  • STRATEGIES FOR LEGIONELLA CONTROL AND THEIR APPLICATION IN BUILDING WATER SYSTEMS
  • REGULATIONS AND GUIDELINES ON LEGIONELLA CONTROL IN WATER SYSTEMS
• 1. Introduction
  • CLINICAL DISEASE AND EPIDEMIOLOGIC STUDIES
  • BUILT ENVIRONMENT IS A MAJOR ECOLOGICAL NICHE
  • ORIGIN OF THE STUDY
  • STUDY PURPOSE AND APPROACH
  • ORGANIZATION OF THE REPORT
  • REFERENCES
  • FIGURE 1-1 CITATIONS:
• 2. Diagnosis, Ecology, and Exposure Pathways
  • HUMAN HOST
  • LEGIONELLA SPECIES AND STRAINS
  • MICROBIAL ECOLOGY OF LEGIONELLA
  • EXPOSURE PATHWAYS
  • CONCLUSIONS AND RECOMMENDATIONS
  • REFERENCES
• 3. Quantification of Legionnaires' Disease and Legionella
  • INCIDENCE OF LEGIONELLOSIS IN THE UNITED STATES
  • ENVIRONMENTAL MONITORING
  • QUANTITATIVE MICROBIAL RISK ASSESSMENT FRAMEWORK FOR LEGIONELLA
  • CONCLUSIONS AND RECOMMENDATIONS
  • REFERENCES
• 4. Strategies for Legionella Control and Their Application in Building Water Systems
  • FUNDAMENTAL FACTORS FOR LEGIONELLA CONTROL
  • HOW THESE CONTROLS ARE APPLIED TO SPECIFIC SYSTEMS
  • EMERGING OPPORTUNITIES AND UNINTENDED CONSEQUENCES
  • CONCLUSIONS AND RECOMMENDATIONS
  • REFERENCES
• 5. Regulations and Guidelines on Legionella Control in Water Systems
  • LACK OF FEDERAL LAWS AND REGULATIONS PERTINENT TO LEGIONELLA
  • STATE AND LOCAL REGULATIONS AND OTHER ENFORCEABLE POLICIES
  • GUIDANCE DOCUMENTS
  • REGULATIONS AND POLICIES FROM OTHER COUNTRIES
  • STEPS FORWARD FOR U.S. LEGIONELLA MANAGEMENT
  • REFERENCES
• Acronyms
• Appendix. Biographical Sketches of Committee Members and Staff

Suggested citation:

National Academies of Sciences, Engineering, and Medicine. 2020. Management of Legionella in Water Systems. Washington, DC: The National Academies Press. http://doi.org/10.17226/25474.

Digital Object Identifier: http://doi.org/10.17226/25474

Library of Congress Control Number: 2019954617

Cover credit: Kyoko Kurosawa

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