Legionella And Risk Management

Introduction

Legionella is a naturally occurring organism named for its identification with Legionnaires' Disease, (Legionellosis), the lung infection and form of pneumonia that caused 34 deaths at a 1976 American Legion Convention in Philadelphia. It has been estimated that 50 to 70 percent of large buildings are colonized to some extent with Legionella. Serious illness may result when the bacteria grow, or amplify, in water systems. Legionella bacteria are one of the top three causes of non-epidemic, community-acquired pneumonia, and are cited as the indoor building contaminant bacteria most likely to result in mortality.

Healthy non-smokers rarely contract Legionnaires’ Disease, which occurs in approximately 5 percent or less of people who are exposed. However, the fatality rate is higher compared to other forms of pneumonia: approximately 15 percent in community-acquired cases, and 40 percent in healthcare settings. In the United States, approximately 12,000 to 30,000 community-acquired (non-healthcare) cases of pneumonia are caused by Legionella each year. An additional 25,000 cases are estimated to occur within healthcare facilities.

Water systems that are not properly maintained to control Legionella bacteria have the potential to result in bodily injury and property damage claims and legal defense expenses for building owners and property managers. Responding to an outbreak is considerably more costly than being proactive. Reports of the initial costs to respond to an outbreak of Legionnaires’ Disease range between $500,000 to $1 million within the first 30 days of the initial response. A Legionella-free water source is not likely feasible; therefore, implementing a proactive program that strives to maintain a Legionella concentration and incidence as low as reasonably achievable is essential.

Exposure Sources

Illness is often associated with cooling towers and potable water systems. Legionnaires' disease has been linked to exposure to contaminated water supplies in residences, commercial office buildings, rehabilitation centers, nursing homes and industrial water supplies. The source of the bacteria in a domestic hot water system is commonly the city water supply, with the bacteria present at low, usually undetectable concentrations. Legionella may survive the water treatment process due to relative resistance to low levels of chlorine. In the building water systems, the bacteria may grow in concentration and spread to increase the risk of exposure.

Improper operation and maintenance of water disseminating devices or systems increases their potential to harbor, amplify and transmit Legionella. Water systems associated with Legionnaire’s Disease include:

• Domestic hot water distribution systems — the primary source of infections that develop in healthcare settings and a significant source for other sporadic cases
• Cooling towers and evaporative condensers (swamp coolers)
• Spas and whirlpools (on display or otherwise in use)
• Humidifiers
• Supermarket reservoir misters
• Respiratory therapy equipment
• Water fountains
• Hot springs (artificial waterfalls)
• Dental hygiene equipment
• Cold water systems (ice machines, storage tanks)
• Fire suppression systems

Transmission

Current data suggests that the risk of disease is influenced not by the quantity of Legionella present in one given (sample) location, but rather the extent of contamination – the number and percentage of sites testing positive in a building. An individual may be exposed by inhaling aerosols, fine sprays, mists or other microscopic droplets of water contaminated with Legionella. Exposure may also occur when choking spontaneously during drinking, ingesting, and swallowing (aspiration), which is a greater risk in a health care setting. Legionnaires’ Disease is not known to pass from person to person.

Building Systems And Equipment Risk Factors

Understanding the causes and likelihood of growth throughout a building system is necessary to reduce the risk of disease. Data from hospital-based studies indicate that when Legionella contamination was detected in more than 30 percent of all the sites sampled, cases of disease were often identified. The major factors that contribute to Legionella's growth and amplification include:

1. Stagnant water conditions and/or systems design configurations that produce stagnation, such as side-arm and dead leg piping.
2. Warm water temperatures from 68 to 122°F (optimal growth at 95 to 113°F)
3. Bulk water pH in the range of 5.0 to 8.5
4. Sediment, scale, deposits, and biofilm, which also support growth of very important supporting microbiota (including algae and many bacteria) that supply essential nutrients for Legionella
5. The presence of certain amoebae and other protozoa that harbor Legionella as endosymbionts – allowing Legionella to thrive and amplify by resisting biocides.

Water Testing And Sampling

There is consensus that in buildings with a highly susceptible population (e.g., health care), routine testing of hot water systems is advisable; it is recommended for cooling towers, hot tubs and water distribution systems especially where people at high risk might be exposed. Routine testing in the absence of disease remains controversial (as to utility) for other settings. An extensive sampling program is probably not called for outside the health care environment. For commercial properties, concentrating on the hot water heater drain point and distal (discharge) points may be more appropriate and feasible.

Experience is required to interpret results and determine what actions to take in the case of a positive result. The presence of Legionella within a water system does not necessarily require immediate action if the percentage of sites positive is low. A qualified consultant experienced in Legionella water system sampling and laboratory analysis interpretation should be retained.

Guidelines And Action Levels

There is no federal standard pertaining to Legionella concentrations in water systems or for verification, assessment and auditing of these systems for Legionella. However, in February of 2008, the Veterans Health Administration (VHA) issued Directive 2008-010 to provide for annual evaluation of its inpatient facilities for Legionella risk. This document appears to be consistent with recent data indicating that percentage of positive test sites is a significant indicator of risk. This presents a departure from earlier, unverified, guidance that focused solely on the concentration in a given sample (e.g., as promulgated by the U.S. Department of Occupational Safety and Health Administration), and is the first such well-established national guidance to gain prominence on the subject. As such it may represent emerging federal guidance.

The VHA Directive indicates that a threshold percentage of sites testing positive should trigger certain response actions. Definition of the threshold is left to the specific facility, but recommended to be 30 percent (positive results). The directive offers an alternative in the annual screening of the facility’s healthcare-acquired pneumonia patients for Legionella. Clearly, this latter approach would be less practical in a non-healthcare setting.

Preventive Measures And Maintenance

Risk management strategies for Legionella should incorporate a multi-level approach aimed at controlling the growth, survival and dissemination of the bacteria. Incorporating this type of redundancy will maintain a safe environment if one preventive measure is ineffective. Specific elements include:

• Managerial responsibilities and reporting requirements
• System assessment of buildings and devices that are potential sources of Legionella. This assessment should consider the susceptibility of those who may be exposed.
• Control measures to prevent the growth, survival and dissemination of Legionella
• Construction/renovation controls to ensure that system modifications or new installations do not create pipework with intermittent or no water flow
• Operational monitoring to ensure that control measures/equipment are functioning properly whenever devices are in use
• Verification procedures and mechanisms for surveillance and audit of risk management plans
• Proper training on the above elements for responsible individuals

Detection of Legionella should trigger a review of risk management procedures. Written procedures for decontamination of devices should be available to deal with an outbreak of illness or for other conditions that have been specified as constituting a substantial risk.

Creation of a Waterborne Pathogens Control Program is an effective tool for increasing building owner and property manager awareness of Legionella risks and appropriate controls. The elements of the plan can be used to create a training program for staff responsible for building water systems and maintenance. Effective implementation of a water safety plan and periodic review of controls will establish a standard of care and should help reduce potential liabilities and claims costs.

References

1. Allegheny County Health Department, Approaches to Prevention and Control of Legionella Infection in Allegheny County Health Care Facilities, 1997
2. ASHRAE Guideline 12-2000, Minimizing the Risk of Legionellosis Associated with Building Water Systems. American Society of Heating, Refrigeration and Air-conditioning Engineers. Atlanta, GA.
3. Centers for Disease Control and Prevention. Procedures for the recovery of Legionella from the environment. U.S. Department of Health and Human Services. Atlanta, GA, 1992.
4. Darelid, J. 2002. Control of nosocomial Legionnaires’ disease by keeping the circulating hot water temperature above 55°C: experience from a 10-year surveillance programme in a district general hospital. J. Hosp. Infect. 50:213?–?219.
5. The European Working Group for Legionella Infections (EWGLI), The European Guidelines for Control and Prevention of Travel Associated Legionnaires' Disease, http://www.ewgli.org/data/european_guidelines.htm
6. Flannery, B. 2006. "Reducing Legionella colonization of water systems with monochloramine." Emer. Infect. Dis. 12(4):588–596.
7. Freije, M. Legionellae control in health-care facilities: A guide for minimizing risk. H.C. Information Resources, INC. Indianapolis, IN 1996.
8. Grieg, J.; et al 2004. An outbreak of Legionnaire’s disease at the Melbourne Aquarium, April 2000: investigation and case-control studies. The Medical Journal of Australia 180(11)566-572.
9. Kim, B.R.; Anderson,J.E.; Mueller,S.A.; Gaines,W.A.; Kendall,A.M. Literature review-efficacy of various disinfectants against Legionella in water systems. Water Res.
10. Kool, J. 1999. "Hospital characteristics associated with colonization of water systems by Legionella and risk of nosocomial Legionnaires’ disease: a cohort study of 15 hospitals." Infect. Control Hosp. Epidemiol. 20:798-805.
11. Kusnetsov, J. 2003. "Colonization of hospital water systems by legionellae, mycobacteria and other heterotrophic bacteria potentially hazardous to risk group patients." APMIS 111:546?–?556.
12. Legionella, State of the Art 30 Years after its Recognition. ASM Press, 2006
13. LEGIONELLA 2003: An Update and Statement by the Association of Water Technologies (AWT), June 2003
14. Legionella Lawsuits: What to Expect and How to Prepare, by Hans A. Nilges, ESQ.
15. Leoni, E.; De Luca,G.; Legnani,P.P.; Sacchetti,R.; Stampi,S.; Zanetti,F.2005. Legionella waterline colonization: detection of Legionella species in domestic, hotel and hospital hot water systems. J.Appl.Micribiol. 98;373-379.
16. Lin YE, Vidic RD, Stout JE, et al. Legionella in water distribution systems. J Amer Water Works Assoc, 1998; 90:112-121.
17. Marston BJ, Plouffe JF, File TM, et al. Incidence of community-acquired pneumonia requiring hospitalization; results of a population based active surveillance study in Ohio. Arch Intern Med, 1997; 157:1709-1718.
18. Muraca PW, Stout JE, Yu VL. Environmental aspects of Legionnaires' disease. J Amer Water Works Assoc, 1988; 80:78-86.
19. Muraca, P.W.; Stout, J.E.; Yu, V.L.; et al Legionnaires' disease in the work environment: implications for environmental health. 1988. Am Indus Hyg Assoc J. 49: 584-590.
20. Occupational Safety and Health Administration. 1999. OSHA Technical Manual Section III, Chapter 7: Legionnaires’ Disease. U.S. Department of Labor. Salt Lake City, UT
21. Occupational Safety and Health Administration. 1998. OSHA Hazard Information Bulletin. Legionnaires’ disease risk for workers in plastic injection molding industry. U.S. Department of Labor. Salt Lake City, UT
22. U.S. Department of Labor, Occupational Safety and Health Administration (OSHA), http://www.osha.gov/dts/osta/otm/legionnaires/disease_rec.html
23. OSHA Instruction TED 1.15 CH-1. Legionnaires’ disease. Section II, Chapter 7. Office of Science and Technology. 1996.
24. State of Maryland Department of Health & Mental Hygiene. Report of the Maryland Scientific Working Group to Study Legionella in Water Systems in Healthcare Institutions, June. 2000.
25. Stout JE, Yu VL, Muraca P, et al. Potable water as the cause of sporadic cases of community-acquired Legionnaires' disease. New Engl J Med, 1992; 326:151-154.
26. Stout JE, Yu VL. Current concepts: Legionellosis. N Engl J Med, 1997; 337:682-687.
27. Stout JE, Yu VL. Legionella in the hospital water supply: a plea for decision making based on evidence-based medicine. Infect Control Hosp Epidemiol, 2001; 22:670-672.
28. Stout, J.E.; Muder, R.R.; Vaccarello, S.; et.al. 2007. Role of environmental surveillance in determining risk for nosocomial Legionnaires' disease: a national surveillance study with clinical correlations. Infect. Control Hosp. Epid. (In Press).
29. Stout J.E. Preventing Legionnaires’ Disease. IAQ Application. June 2007. ASHRAE publication.
30. Vickers, R.M.; Yu, V.L.; Hanna,S.S.; Muraca, P.; Diven, W.; Carmen,N.; Taylor,F.B. 1987. Determinants of Legionella pneumophila contamination of water distribution systems: 15 hospital prospective study. Infect. Control Hosp. Epid. 8: 357-363.
31. World Health Organization (WHO) (2004). Guidelines for Drinking Water Quality, 3rd ed. Vol. 1. Recommendations, Geneva, WHO.
32. Yu, V.L.; Plouffe, J.F.; Castellani-Pastoris, M.; Stout, J.E.; Shousboe, M.; Widmer, A.; Summersgill, J.; File,T.; Heath, C.; Paterson, D. 2002. Distribution of Legionella species and serogroups isolated by culture in consecutive patients with community acquired pneumonia: an international collaborative survey. J.Infect.Dis. 186: 127-128.
33. Yu, V.L., Liu, Z., Stout, J.E., et al. Legionella disinfection of water distribution systems: principles, problems, and practice. Infection Control Hosp Epidemiol, 14, 567-570, 1993.

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Information accurate as of October, 2008.

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