Articles on Legionnaires’ Disease

About the Disease

Legionnaires' disease is a severe, often lethal, form of pneumonia. It's caused by the bacterium Legionella pneumophila found in both potable and nonpotable water systems. Each year, an estimated 10,000 to 18,000 people are infected with the Legionella bacteria in the United States.

It is not uncommon for patients with Legionnaires' disease to be admitted to the intensive care unit. Some will suffer long-term impaired health-related quality of life.  A study of outbreak survivors showed persistence of fatigue (75%), neurologic symptoms (66%) and neuromuscular symptoms (63%) in months after an outbreak. See Share Your Story for a first-hand account of the severity of this disease.

Articles on Legionnaires' Disease

Prevention of Hospital-Acquired Legionellosis

by Lin YE, Stout JE and Yu VL. Curr Opin Infect Dis. 2011. 24(4):350-6.More hospitals are facing the dilemma of Legionella outbreaks as they discover the drinking water is the source. This article provides an update of the use of PCR detection for water, the use of CFU/mL vs distal site positivity as an indicator of risk, risk assessment, neurologic complications in patients, and new laboratory tests for patient management.


Controlling Legionella in Hospital Drinking Water: An Evidence-Based Review of Disinfection Methods

by Lin YE, Stout JE and Yu VL. Infect Control Hosp Epidemiol. 2011 32(2):166-173."State-of-the-Art" disinfection methods applied to drinking water are reviewed. Many commonly-used approaches are not only non-evidence based and ineffective but are expensive and logistically tedious to implement. Efficacy must be defined by disappearance of Legionella from the drinking water. Disinfection concentrations and % distal site positivity must be measured regularly for the lifespan of the system. Infection control professionals must take the lead in selecting the disinfection modality and the commercial vendor. Evidence-based medicine with documented record of success should be the criteria for selection; anecdotal testimonials are often unreliable. Healthcare facility managers should be consulted in an advisory role.


Role of Environmental Surveillance in Determining the Risk of Hospital-Acquired Legionellosis: A National Surveillance Study With Clinical Correlations

by Stout JE and the Legionella Study Group. Infect Control Hosp Epidemiol. 2007 28(7):818-24.In a prospective study involving 20 US hospitals, environmental culturing for Legionella followed by clinical surveillance uncovered cases of hospital-acquired Legionella pneumonia that would have otherwise gone unrecognized.


Environmental culturing for Legionella: Can we build a better mouse trap?

by Stout JE, Yu VL (Am J Infect Control 2010;38:341-3)This report discusses best practices for Legionella detection in water systems. Topics include swab vs. water, frequency of culturing, which sites to culture, and an overall action plan.


Cooling towers and legionellosis: A conundrum with proposed solutions

by Yu VL (Int J Hyg Environ Health 2008;211:239-234)A skeptical critique of the role of cooling towers in causing Legionnaires' disease.


Legionnaires' Disease in Long-Term Care Facilities: Overview and Proposed Solutions

by Meena H. Seenivasan, Victor L. Yu, Robert R. Muder (Journal of American Geriatrics Society, 53:875-880, 2005.)Pneumonia is a leading cause of morbidity and mortality in nursing home patients. In acute care hospitals, there is considerable evidence to indicate that Legionnaires' disease is a significant cause of nosocomial pneumonia, the source of which is the potable water system. A relatively limited amount of data exists as to the role of Legionnaires' disease as a cause of pneumonia acquired in long-term care residents.


Preventing Legionellosis

by Janet E. Stout (ASHRAE Journal, Oct 2007)Legionella guidelines from four public health agencies are reviewed. Many recommendations for infection control and healthcare facilities management are not evidence-based, and also known to be ineffective, costly, and logistically-tedious. Rigorous guidelines based on scientific data should be the criteria for making public health recommendations.


Community-acquired Legionnaires' disease: Implications for underdiagnosis and laboratory testing

by Victor L. Yu and Janet E. Stout (Clin Infect Dis 2008;46:1365-1367)Legionnaires' disease is an uncommon but not rare cause of pneumonia. Legionnaires' disease was considered to be an unusually severe pneumonia, given the mortality rate (29%) at the initial outbreak during the American Legion convention at the Philadelphia, Pennsylvania, hotel and for the patients first reported with nosocomial Legionnaires' disease.


A proactive approach to prevention of health care–acquired Legionnaires’ disease: The Allegheny County (Pittsburgh) experience

by Squier CL, Association for Professionals in Infection Control - 3 Rivers Chapter, and the Allegheny County Health Dept. (American Journal of Infection Control, 2005)Health care-acquired legionellosis declined significantly after the issuance of proactive guidelines for routine environmental culturing for Legionella in all Allegheny County healthcare facilities. The decline was due to increasing index of suspicion by physicians and initiation of disinfection methods if indicated. Two unanticipated benefits were (1) cases of legionellosis in the community and long-term care facilities were uncovered and (2) litigation and unfavorable publicity involving ACHD hospitals ceased.


Legionella surveillance: political and social implications--a little knowledge is a dangerous thing.

by Victor L. Yu (Journal of Infectious Diseases 185:259-261, 2002, University of Chicago Press)Fear of adverse publicity and litigation are obstacles to a rational scientific approach to Legionnaires' disease prevention. "Surveillance should be complemented by education of the public and lay media. The public must be informed that Legionella are common colonizers (as are Pseudomonas species) of man-made water distribution systems that are rarely pathogenic for immunocompetent hosts and that Legionnaires' disease is not a contagious disease. Ignorance leads to panic and panic leads to irrational actions. We have observed the implementation of emergency measures that are expensive, logistically tedious, and have little impact on the risk of acquiring Legionnaires' disease."


Legionnaries' Disease Contracted from Patient Homes: The Coming of the Third Plague?

by M.L. Pedro-Botet, Janet E. Stout and Victor L. Yu Eur J Clin Microbiol Infect Dis, 21:699-705, 2002, Springer-VerlagIn biblical times, ten plagues were inflicted on Egypt, causing fear and consternation. The plagues included locusts, frogs, hail, and, ultimately, the deaths of the first-born sons of Egypt [1]. Similarly, Legionnaires' disease swept into our medical consciousness like a plague, causing fear and consternation.


Approaches to Prevention and Control of Legionella Infection

Allegheny County Health Department Guidelines A task force was convened in June 1992 to develop practical guidelines for use in healthcare institution to prevent Legionnaires' disease. The task force was composed of expert members of the medical, public health, plumbing, and drinking water regulatory agencies in Allegheny County, Pennsylvania. This report consists of their consensus opinion of recommendations for use in healthcare institutions to minimize the occurrence of Legionella in water systems and thus, reduce the incidence of Legionnaires' disease in hospitalized.


Culture Your Water System for Legionella or Not?

Yu, V.L., " Resolving the Controversy on Environmental Cultures for Legionella: A Modest Proposal, Infection Control and Hospital Epidemiology, 19, pp. 893-897, 1998This editorial reviews the proactive position of Pittsburgh investigators in prevention of hospital-acquired Legionnaires' disease. Pittsburgh investigators document that knowledge that the hospital water is colonized is a scientifically-based method that effectively prevents cases of hospital-acquired Legionnaires' disease. In contrast, U.S. CDC does not favor culturing the hospital water supply unless one or more hospitalized patients contract Legionnaires' disease. The scientific evidence and effectiveness of both positions is reviewed.