A Methodology for Classifying Root Causes of Outbreaks of Legionnaires’ Disease: Deficiencies in Environmental Control and Water Management

Abstract

We piloted a methodology for collecting and interpreting root cause—or environmental deficiency (ED)—information from Legionnaires’ disease (LD) outbreak investigation reports. The methodology included a classification framework to assess common failures observed in the implementation of water management programs (WMPs). We reviewed reports from fourteen CDC-led investigations between 1 January 2015 and 21 June 2019 to identify EDs associated with outbreaks of LD. We developed an abstraction guide to standardize data collection from outbreak reports and define relevant parameters. We categorized each ED according to three criteria: ED type, WMP-deficiency type, and source of deficiency. We calculated the prevalence of EDs among facilities and explored differences between facilities with and without WMPs. A majority of EDs identified (81%) were classified as process failures. Facilities with WMPs (n = 8) had lower prevalence of EDs attributed to plumbed devices (9.1%) and infrastructure design (0%) than facilities without WMPs (n = 6; 33.3% and 24.2%, respectively). About three quarters (72%) of LD cases and 81% of the fatalities in our sample originated at facilities without a WMP. This report highlights the importance of WMPs in preventing and mitigating outbreaks of LD. Building water system process management is a primary obstacle toward limiting the root causes of LD outbreaks. Greater emphasis on the documentation, verification, validation, and continuous program review steps will be important in maximizing the effectiveness of WMPs.

Factors That Affect Legionella Positivity in Healthcare Building Water Systems from a Large, National Environmental Surveillance Initiative

“…A separate review of legionellosis in VHA facilities between 2014 and 2016 found that healthcare-associated cases with overnight stays decreased . Together, these reports from VHA suggest the value of comprehensive Legionella primary prevention programs in improving patient safety, and align with insights from more focused outbreak reviews. , Further review to examine potential correlations between Legionella positivity in water and clinical cases is underway.…”

“…21 Together, these reports from VHA suggest the value of comprehensive Legionella primary prevention programs in improving patient safety, and align with insights from more focused outbreak reviews. 31,32 Further review to examine potential correlations between Legionella positivity in water and clinical cases is underway. The largest changes in positivity rates over the four years were observed for total Legionella and L. pneumophila (any serogroup).…”

Pinpointing drivers of widespread colonization of Legionella pneumophila in a green building: Roles of water softener system, expansion tank, and reduced occupancy

“…Building water management practices play an important role in controlling water quality in building water systems (Clopper et al, 2021;Logan-Jackson, A. R. and Rose, 2021), however building water management plans are typically developed on an ad-hoc basis using broad guidelines as a reference point rather than using a tailored site-specific approach (National Academies of Sciences, 2019). Given the need for and importance of comprehensive water management programs in large, commercial-institutional buildings and the human health threat from Legionella infection, it is crucial to assess the likelihood of a hazard and reduce exposures to ensure occupants' safety.…”

“…Water management plans are effective in reducing the likelihood of a Legionella spp. outbreak (Clopper et al, 2021). Several corrective actions were implemented by the building facility managers after they were informed about the deteriorating water quality during the duration of reduced occupancy.…”

Water Security and Nutrition: Current Knowledge and Research Opportunities

“…Inhalation of mist containing bacteria can also cause respiratory disease. Outbreaks of Legionnaires’ disease, for instance, are most often attributed to poor water treatment and infrastructure maintenance (e.g., infrequent cleaning of heating, ventilation, and air conditioning systems) in communities with centralized piped water networks ( 168 , 169 ). Finally, antibiotic-resistant bacteria in drinking water are also becoming increasingly common and pose significant health risks when resistance is transferred to human pathogens ( 170 ).…”