Managing <i>Legionella pneumophila</i> in Water Systems

LeChevallier, Mark W.

doi:10.1002/awwa.1444

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…A definitive shared responsibility model, across all stakeholders, is urgently needed to better prevent LD in the future . There is increasing recognition of potential water utility responsibility in the management of Legionella risk in municipal water systems, but there are still significant uncertainties in how they should respond and communicate to the public about Legionella risks. , …”

Section: Discussionmentioning

confidence: 99%

“…34 There is increasing recognition of potential water utility responsibility in the management of Legionella risk in municipal water systems, 35 but there are still significant uncertainties in how they should respond and communicate to the public about Legionella risks. 35,36 A temporary lapse in corrosion control during water treatment plant upgrades is lawful for small systems under the current LCR, and increased WLL monitoring or public notification is not required. Due to the 3-year LCR reporting period in Quincy, no WLL data were collected during the 6month lapse in phosphate or for 17 months thereafter.…”

Section: ■ Implicationsmentioning

confidence: 99%

“…33 A definitive shared responsibility model, across all stakeholders, is urgently needed to better prevent LD in the future. 34 There is increasing recognition of potential water utility responsibility in the management of Legionella risk in municipal water systems, 35 but there are still significant uncertainties in how they should respond and communicate to the public about Legionella risks. 35,36 A temporary lapse in corrosion control during water treatment plant upgrades is lawful for small systems under the current LCR, and increased WLL monitoring or public notification is not required.…”

Section: ■ Implicationsmentioning

confidence: 99%

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Did Municipal Water Distribution System Deficiencies Contribute to a Legionnaires’ Disease Outbreak in Quincy, IL?

Rhoads

Keane²,

Spencer

et al. 2020

Environ. Sci. Technol. Lett.

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Fifty-eight people were sickened and 12 died from a Legionnaires' disease (LD) outbreak in Quincy, IL, in 2015. The initial outbreak investigation identified deficiencies at the Illinois Veteran's Home (IVHQ), but these did not account for four community-acquired cases that occurred concurrently with no IVHQ exposure. We broaden the investigation to evaluate seven lines of evidence and assess whether municipal drinking water supply deficiencies potentially contributed to a community-wide outbreak. Notably, 3−6 months prior to the outbreak, the primary disinfectant was changed and corrosion control was interrupted, causing a sustained decrease in disinfectant residuals throughout Quincy's distribution system. We hypothesize this created more favorable conditions for Legionella growth throughout the system and an increase in water lead levels. These municipal system deficiencies were not identified in prior investigations of the outbreak, but their impacts on public health outcomes are consistent with those of the 2014−2016 Flint Water Crisis. However, they occurred in Quincy without any legal violations in the municipal water system or public acknowledgment of community-wide health risks. This study supports the critical need for improved data collection during changes in municipal water treatment. Additional regulatory and communication requirements can better protect public health from both LD and lead.

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Section: Discussionmentioning

confidence: 99%

Section: ■ Implicationsmentioning

confidence: 99%

Section: ■ Implicationsmentioning

confidence: 99%

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Did Municipal Water Distribution System Deficiencies Contribute to a Legionnaires’ Disease Outbreak in Quincy, IL?

Rhoads

Keane²,

Spencer

et al. 2020

Environ. Sci. Technol. Lett.

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“…Figure 13 shows the experience of a utility that detected L. pneumophila in an area of the distribution system that was under construction. The area had plans for several hundred homes, but at the time only 73 houses had been built [34,182]. The area is served by a 12 inch (30.5 cm) main, so detention times were very long.…”

Section: Legionella Pneumophilamentioning

confidence: 99%

Opportunistic Pathogens in Drinking Water Distribution Systems—A Review

LeChevallier,

Prosser,

Stevens

2024

Microorganisms

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In contrast to “frank” pathogens, like Salmonella entrocolitica, Shigella dysenteriae, and Vibrio cholerae, that always have a probability of disease, “opportunistic” pathogens are organisms that cause an infectious disease in a host with a weakened immune system and rarely in a healthy host. Historically, drinking water treatment has focused on control of frank pathogens, particularly those from human or animal sources (like Giardia lamblia, Cryptosporidium parvum, or Hepatitis A virus), but in recent years outbreaks from drinking water have increasingly been due to opportunistic pathogens. Characteristics of opportunistic pathogens that make them problematic for water treatment include: (1) they are normally present in aquatic environments, (2) they grow in biofilms that protect the bacteria from disinfectants, and (3) under appropriate conditions in drinking water systems (e.g., warm water, stagnation, low disinfectant levels, etc.), these bacteria can amplify to levels that can pose a public health risk. The three most common opportunistic pathogens in drinking water systems are Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa. This report focuses on these organisms to provide information on their public health risk, occurrence in drinking water systems, susceptibility to various disinfectants, and other operational practices (like flushing and cleaning of pipes and storage tanks). In addition, information is provided on a group of nine other opportunistic pathogens that are less commonly found in drinking water systems, including Aeromonas hydrophila, Klebsiella pneumoniae, Serratia marcescens, Burkholderia pseudomallei, Acinetobacter baumannii, Stenotrophomonas maltophilia, Arcobacter butzleri, and several free-living amoebae including Naegleria fowleri and species of Acanthamoeba. The public health risk for these microbes in drinking water is still unclear, but in most cases, efforts to manage Legionella, mycobacteria, and Pseudomonas risks will also be effective for these other opportunistic pathogens. The approach to managing opportunistic pathogens in drinking water supplies focuses on controlling the growth of these organisms. Many of these microbes are normal inhabitants in biofilms in water, so the attention is less on eliminating these organisms from entering the system and more on managing their occurrence and concentrations in the pipe network. With anticipated warming trends associated with climate change, the factors that drive the growth of opportunistic pathogens in drinking water systems will likely increase. It is important, therefore, to evaluate treatment barriers and management activities for control of opportunistic pathogen risks. Controls for primary treatment, particularly for turbidity management and disinfection, should be reviewed to ensure adequacy for opportunistic pathogen control. However, the major focus for the utility’s opportunistic pathogen risk reduction plan is the management of biological activity and biofilms in the distribution system. Factors that influence the growth of microbes (primarily in biofilms) in the distribution system include, temperature, disinfectant type and concentration, nutrient levels (measured as AOC or BDOC), stagnation, flushing of pipes and cleaning of storage tank sediments, and corrosion control. Pressure management and distribution system integrity are also important to the microbial quality of water but are related more to the intrusion of contaminants into the distribution system rather than directly related to microbial growth. Summarizing the identified risk from drinking water, the availability and quality of disinfection data for treatment, and guidelines or standards for control showed that adequate information is best available for management of L. pneumophila. For L. pneumophila, the risk for this organism has been clearly established from drinking water, cases have increased worldwide, and it is one of the most identified causes of drinking water outbreaks. Water management best practices (e.g., maintenance of a disinfectant residual throughout the distribution system, flushing and cleaning of sediments in pipelines and storage tanks, among others) have been shown to be effective for control of L. pneumophila in water supplies. In addition, there are well documented management guidelines available for the control of the organism in drinking water distribution systems. By comparison, management of risks for Mycobacteria from water are less clear than for L. pneumophila. Treatment of M. avium is difficult due to its resistance to disinfection, the tendency to form clumps, and attachment to surfaces in biofilms. Additionally, there are no guidelines for management of M. avium in drinking water, and one risk assessment study suggested a low risk of infection. The role of tap water in the transmission of the other opportunistic pathogens is less clear and, in many cases, actions to manage L. pneumophila (e.g., maintenance of a disinfectant residual, flushing, cleaning of storage tanks, etc.) will also be beneficial in helping to manage these organisms as well.

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“…The following recommendations were l used in a recent study of L. pneumophila in public water systems [5] and the basis for this guidance was outlined in a prior publication [18]. The protocol was developed in collaboration with regulators from the State of Washington and consistent with a quantitative microbial risk assessment of L. pneumophila [19] and a number of national and international guidelines (Table 4). Guidelines are not yet available for molecular methods, although the Spartan Cube reports their genomic units with a conversion to colony forming units (CFU/mL).…”

Section: Develop L Pneumophila Response and Communication Planmentioning

confidence: 99%

Guidance on Developing a Legionella pneumophila Monitoring Program for Utility Distribution Systems

2021

Health Educ Public Health

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Despite recommendations for water utilities to "validate treatment performance by routine monitoring for L. pneumophila," little guidance is available on how exactly to accomplish this goal. The objective of this study was to outline a process by which water utilities can plan and implement such a monitoring program. The guidance is based on the experience gained through several prior research studies and input from several state public health authorities. Unfortunately, there is no such guidance from U.S. federal agencies. The seven step process guides utilities to consider program objectives, key internal and external stakeholders, monitoring protocols and training, communications, support for testing and reporting, pilot testing and program documentation. There are a number of commercially available tests for L. pneumophila, although some have been more widely evaluated by third-party entities than others. In all cases, it is important for utilities to consider how program results will be communicated and to solicit input on the process from relevant stakeholders. In all cases, it is important for utilities to consider how that program results will be communicated and to solicit input on the process from relevant stakeholders. Finally, program documentation and sharing of the results with the public and other utilities is encouraged to help other water utilities navigate the same path and demonstrate industry leadership.

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Managing Legionella pneumophila in Water Systems

Cited by 7 publications

References 12 publications

Did Municipal Water Distribution System Deficiencies Contribute to a Legionnaires’ Disease Outbreak in Quincy, IL?

Did Municipal Water Distribution System Deficiencies Contribute to a Legionnaires’ Disease Outbreak in Quincy, IL?

Opportunistic Pathogens in Drinking Water Distribution Systems—A Review

Guidance on Developing a Legionella pneumophila Monitoring Program for Utility Distribution Systems

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