Growth of<i>Legionella</i>during COVID-19 lockdown stagnation

Rhoads, William J.; Hammes, Frederik

doi:10.1039/d0ew00819b

Cited by 33 publications

(37 citation statements)

References 35 publications

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“…Stagnation as a catch-all term for water aging is problematic because it can occur at a single outlet or an entire system, for hours to years, and is coincident with many biotic and abiotic water quality changes that occur to different extents within or among different systems [ 8 ]. In this study, we specifically reserve the term “stagnation” to describe the lack of water demand and flow.…”

Section: Discussionmentioning

confidence: 99%

“…The apparent contradictions in the impact of stagnation are complicated by the all-encompassing nature in which the term is typically used [ 8 ]. “Stagnation” has been used to describe a range of plumbing conditions including no water flow or exchange [ 1 ], existence of dead-end pipes [ 9 ], intermittent use at individual outlets [ 7 ], and generally elevated water residence time caused by low water demand and/or over-sized components [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

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Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

et al. 2022

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When stay-at-home orders were issued to slow the spread of COVID-19, building occupancy (and water demand) was drastically decreased in many buildings. There was concern that widespread low water demand may cause unprecedented Legionella occurrence and Legionnaires’ disease incidence. In lieu of evidenced-based guidance, many people flushed their water systems as a preventative measure, using highly variable practices. Here, we present field-scale research from a building before, during, and after periods of low occupancy, and controlled stagnation experiments. We document no change, a > 4-log increase, and a > 1.5-log decrease of L. pneumophila during 3- to 7-week periods of low water demand. L. pneumophila increased by > 1-log after precautionary flushing prior to reoccupancy, which was repeated in controlled boiler flushing experiments. These results demonstrate that the impact of low water demand (colloquially called stagnation) is not as straight forward as is generally assumed, and that some flushing practices have potential unintended consequences. In particular, stagnation must be considered in context with other Legionella growth factors like temperature and flow profiles. Boiler flushing practices that dramatically increase the flow rate and rapidly deplete boiler temperature may mobilize Legionella present in biofilms and sediment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

et al. 2022

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“…Water stagnation is known to be a critical factor for water-quality decrease, with an inherent impact on Legionella prevalence [93]. For example, De Giglio et al [59] assessed the microbiological water quality in an Italian hospital over 3 months during the COVID-19 lockdown.…”

Section: Water Stagnation Vs Water Flushingmentioning

confidence: 99%

“…The authors found higher concentrations of L. pneumophila after the lockdown, which was attributed to building inoccupation. The work of Rhoads et al [93] provides an interesting overview of the complex topic of water stagnation related to Legionella management. One of the strategies to minimize stagnation problems is water flushing.…”

Section: Water Stagnation Vs Water Flushingmentioning

confidence: 99%

Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

2021

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Legionella is responsible for the life-threatening pneumonia commonly known as Legionnaires’ disease or legionellosis. Legionellosis is known to be preventable if proper measures are put into practice. Despite the efforts to improve preventive approaches, Legionella control remains one of the most challenging issues in the water treatment industry. Legionellosis incidence is on the rise and is expected to keep increasing as global challenges become a reality. This puts great emphasis on prevention, which must be grounded in strengthened Legionella management practices. Herein, an overview of field-based studies (the system as a test rig) is provided to unravel the common roots of research and the main contributions to Legionella’s understanding. The perpetuation of a water-focused monitoring approach and the importance of protozoa and biofilms will then be discussed as bottom-line questions for reliable Legionella real-field surveillance. Finally, an integrated monitoring model is proposed to study and control Legionella in water systems by combining discrete and continuous information about water and biofilm. Although the successful implementation of such a model requires a broader discussion across the scientific community and practitioners, this might be a starting point to build more consistent Legionella management strategies that can effectively mitigate legionellosis risks by reinforcing a pro-active Legionella prevention philosophy.

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“…Stagnant water can have chemical and microbiological contaminants that pose potential health risks to occupants [80] . In particular, water stagnation in buildings may lead to Legionella growth, but study on the relationship between Legionnaires' disease cases and COVID-19 lockdowns is still limited [81] . This should be considered to ensure the safety building water system and devices when reopening buildings.…”

Section: State Of the Knowledge And Research Needsmentioning

confidence: 99%

Water science under the global epidemic of COVID-19: Bibliometric tracking on COVID-19 publication and further research needs

Zhao

Wei

et al. 2021

Journal of Environmental Chemical Engineering

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Growth ofLegionelladuring COVID-19 lockdown stagnation

Abstract: While “avoiding stagnation” has been the mantra of many building water quality experts, the foundational support for how this terminology is used in peer-reviewed publications and building water management guidelines...

Cited by 33 publications

References 35 publications

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Legionella and Biofilms—Integrated Surveillance to Bridge Science and Real-Field Demands

Water science under the global epidemic of COVID-19: Bibliometric tracking on COVID-19 publication and further research needs

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