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Legionella growth in healthcare building water systems can result in legionellosis, making water management programs (WMPs) important for patient safety. However, knowledge is limited on Legionella prevalence in healthcare buildings. A dataset of quarterly water testing in Veterans Health Administration (VHA) healthcare buildings was used to examine national environmental Legionella prevalence from 2015 to 2018. Bayesian hierarchical logistic regression modeling assessed factors influencing Legionella positivity. The master dataset included 201,146 water samples from 814 buildings at 168 VHA campuses. Overall Legionella positivity over the 4 years decreased from 7.2 to 5.1%, with the odds of a Legionella -positive sample being 0.94 (0.90-0.97) times the odds of a positive sample in the previous quarter for the 16 quarters of the 4 year period. Positivity varied considerably more at the medical center campus level compared to regional levels or to the building level where controls are typically applied. We found higher odds of Legionella detection in older buildings (OR 0.92 [0.86-0.98] for each more recent decade of construction), in taller buildings (OR 1.20 [1.13-1.27] for each additional floor), in hot water samples (O.R. 1.21 [1.16-1.27]), and in samples with lower residual biocide concentrations. This comprehensive healthcare building review showed reduced Legionella detection in the VHA healthcare system over time. Insights into factors associated with Legionella positivity provide information for healthcare systems implementing WMPs and for organizations setting standards and regulations.

Background: Guidelines recommend testing hospitalized patients with community-acquired pneumonia (CAP) for Legionella pneumophila only if the infection is severe or risk factors are present. There are no validated models for predicting Legionella., Objective: To derive and externally validate a model to predict a positive Legionella test., Design, Setting and Participants: Diagnostic study of adult inpatients with pneumonia using data from 177 US hospitals in the Premier Healthcare Database (training and hold-out validation sets) and 12 Cleveland Clinic Health System (CCHS) hospitals (external validation set). We used multiple logistic regression to predict positive Legionella tests in the training set, and evaluated performance in both validation sets., Main Outcome and Measures: The outcome was a positive Legionella test. Potential predictors included demographics and co-morbidities, disease severity indicators, season, region, and presence of a local outbreak., Results: Of 166,689 patients hospitalized for pneumonia, 43,070 were tested for Legionella and 642 (1.5%) tested positive. The strongest predictors of a positive test were a local outbreak (odds ratio [OR], 3.4), June-October occurrence (OR, 3.4), hyponatremia (OR, 3.3), smoking (OR, 2.4), and diarrhea (OR, 2.0); prior admission within 6 months (OR, 0.27) and chronic pulmonary disease (OR, 0.49) were associated with a negative test. Model c-statistics were 0.79 in the Premier and 0.77 in the CCHS validation samples. High-risk patients were only slightly more likely to have been tested than lower-risk patients. Compared to actual practice, the model-based testing strategy detected twice as many cases., Conclusions: Although Legionella is an uncommon cause of pneumonia, patient characteristics can identify individuals at high risk, allowing for more efficient testing., (© 2022 The Authors. Journal of Hospital Medicine published by Wiley Periodicals LLC on behalf of Society of Hospital Medicine.)

Introduction: Legionnaires' disease (LD) is a recognised cause of community-acquired pneumonia. However, Legionella is an overlooked pathogen in hospital-acquired pneumonia. The European Surveillance System 2008-2017 found 23% of the Belgian LD reported cases being healthcare-related, with a higher death-rate than in community-acquired patients. This study aims to describe patients admitted for community-acquired LD or affected by hospital-acquired LD and investigate discriminants associated with lethality., Methods: Medical records were retrospectively reviewed at three Belgian University Hospitals, between 1 January 2016 up to 31 January 2019. Hospital-acquired LD was defined as symptom onset at 10 days or more after admission, according to the Centres for Disease Control and prevention. Community-acquired LD was defined as diagnosis at admission or within 10 days after admission., Results: Fifty patients were included in the study, among them 26% were diagnosed with hospital-acquired LD. The case-fatality rate was 22%, with eight of the eleven deceased patients (73%) being in the hospital-acquired LD group. Medical history of asthma or chronic obstructive pulmonary disease and higher sequential organ failure assessment (SOFA) score at diagnosis were more frequently observed in the hospital-acquired LD group. Furthermore, significantly lower SOFA score at diagnosis of LD and higher rates of treatment with levofloxacin or moxifloxacin were observed in survivors., Conclusion: In the current cohort, LD death-rate was mainly driven by hospital-acquired LD patients. Hospital-acquired LD might especially affect patients with chronic respiratory disease. Respiratory fluoroquinolones treatment and lower SOFA score at diagnosis may be associated with favourable outcomes.

Exposure models are useful tools for relating environmental monitoring data to expected health outcomes. The objective of this study was to (1) compare two Legionella shower exposure models, and (2) develop a risk calculator tool for relating environmental monitoring data to estimated Legionella infection risks and Legionnaires' Disease (LD) illness risks. Legionella infection risks for a single shower event were compared using two shower Legionella exposure models. These models varied in their description of partitioning of Legionella in aerosols and aerosol deposition in the lung, where Model 1 had larger and fewer aerosol ranges than Model 2. Model 2 described conventional vs. water efficient showers separately, while Model 1 described exposure for an unspecified shower type (did not describe it as conventional or water efficient). A Monte Carlo approach was used to account for variability and uncertainty in these aerosolization and deposition parameters, Legionella concentrations, and the dose-response parameter. Methods for relating infection risks to illness risks accounting for demographic differences were used to inform the risk calculator web application ("app"). Model 2 consistently estimated higher infection risks than Model 1 for the same Legionella concentration in water and estimated deposited doses with less variability. For a 7.8-min shower with a Legionella concentration of 0.1 CFU/mL, the average infection risks estimated using Model 2 were 4.8 × 10 - 6 (SD=3.0 × 10 - 6 ) (conventional shower) and 2.3 × 10 - 6 (SD=1.7 × 10 - 6 ) (water efficient). Average infection risk estimated by Model 1 was 1.1 × 10 -6 (SD=9.7 × 10 - 7 ). Model 2 was used for app development due to more conservative risk estimates and less variability in estimated dose. While multiple Legionella shower models are available for quantitative microbial risk assessments (QMRAs), they may yield notably different infection risks for the same environmental microbial concentration. Model comparisons will inform decisions regarding their integration with risk assessment tools. The development of risk calculator tools for relating environmental microbiology data to infection risks will increase the impact of exposure models for informing water treatment decisions and achieving risk targets., (Copyright © 2022. Published by Elsevier Ltd.)

Background: Legionnaires' disease (LD) is a serious sometimes fatal pneumonia caused by Legionella pneumophila. The clinical manifestations of LD may be similar to those by caused by Streptococcus pneumoniae. As both conditions can be serious illnesses but requiring different antimicrobial therapies, factors that can help differentiate these types of pneumonias can be helpful in the clinical management of hospitalized patients with bacterial pneumonia. This study aimed to compare clinical features and indicators of disease progression in hospitalized patients with community-acquired pneumonia caused by L. pneumophila and bacteremic S. pneumoniae., Methods: We conducted a retrospective case comparison study of adult patients hospitalized with LD or S. pneumoniae. Data collected included demographic, clinical characteristics, and comorbidities, and outcomes. Data were analyzed using SPS vs 24.0. Multivariable analysis was done using logistic regression with a forward stepwise algorithm., Results: A total of 106 patients met study criteria. The incidence of LD peaked in summer months and S. pneumoniae peaked in the winter quarter. From multivariable analysis predictors of LD were male gender (OR=21.6, p < 0.001), diarrhea (OR=4.5, p = 0.04), body mass index (BMI) (OR=1.13, p = 0.02), hyponatremia (OR=5.6, p = 0.03 and Charlson weighted index of comorbidity (CWIC) score (OR=0.61, p = 0.01). Patients with S. pneumoniae had higher rates of mechanical ventilation, septic shock, and death than those with LD., Conclusions: Our data suggests that variables that may distinguish LD from S. pneumoniae include male gender, diarrhea, hyponatremia, higher temperature on admission, higher BMI and fewer comorbidities. Bacteremic S. pneumoniae was associated with poorer outcomes than LD including higher rates of septic shock, mechanical ventilation, ICU admission, and death., Competing Interests: Conflicts of Interest Statement The authors have no conflicts of interest to declare related to the conduct of this research or its publication., (Copyright © 2022. Published by Elsevier Inc.)

Objectives: Racial and socioeconomic disparities in the incidence of Legionnaires' disease have been documented for the past 2 decades; however, the social determinants of health (SDH) that contribute to these disparities are not well studied. The objective of this narrative review was to characterize SDH to inform efforts to reduce disparities in the incidence of Legionnaires' disease., Methods: We conducted a narrative review of articles published from January 1979 through October 2019 that focused on disparities in the incidence of Legionnaires' disease and pneumonia (inclusive of bacterial pneumonia and/or community-acquired pneumonia) among adults and children (excluding articles that were limited to people aged <18 years). We identified 220 articles, of which 19 met our criteria: original research, published in English, and examined Legionnaires' disease or pneumonia, health disparities, and SDH. We organized findings using the Healthy People 2030 SDH domains: economic stability, education access and quality, social and community context, health care access and quality, and neighborhood and built environment., Results: Of the 19 articles reviewed, multiple articles examined disparities in incidence of Legionnaires' disease and pneumonia related to economic stability/income (n = 13) and comorbidities (n = 10), and fewer articles incorporated SDH variables related to education (n = 3), social support (none), health care access (n = 1), and neighborhood and built environment (n = 6) in their analyses., Conclusions: Neighborhood and built-environment factors such as housing, drinking water infrastructure, and pollutant exposures represent critical partnership and research opportunities. More research that incorporates SDH and multilevel, cross-sector interventions is needed to address disparities in Legionnaires' disease incidence.

Legionella species are the etiological agent of Legionnaires' disease, a pathology easily contracted from water circuits and by the inhalation of aerosol droplets. This bacterium mainly proliferates in water: Legionella pneumophila is the most commonly isolated specie in water environments and consequently in water system, although further Legionella species have frequently been isolated, including Legionella dumoffii. The simultaneous presence of the two species in the water system can therefore lead to the simultaneous infection of several people, giving rise to harmful outbreaks. Ultraviolet inactivation of waterborne microorganisms offers a rapid and effective treatment technique and recently is getting more attention mostly to eliminate unsafe level of contamination. To tackle the issue, the inactivation of the two species of Legionella spp., namely L. pneumophila and L. dumoffii, by means of UV-A light emitting diodes (UV-A LED) system is explored. We used a commercially available UV-A LED at 365 nm wavelength, and the UV-A dose is given incrementally to the Legionellae with a concentration of 10 6  CFU/mL in 0.9% NaCl (aq) solution. In this study, with a UV-A-dose of 1700 mJ/cm 2 , the log-reduction of 3-log (99.9% inactivation) for L. pneumophila and 2.1-log (99.1% inactivation) for L. dumoffii of the contaminated water are achieved. The Electrical Energy per Order (E EO ) is evaluated and showed this system is more economic and efficient in comparison with UV-C and UV-B LEDs. Following the support of this preliminary study with additional tests, aiming to validate the technology, we expect this device may be installed in water plants such as cooling systems or any water purification station in either industrial or home scales to reduce the risk of this infectious disease, preventing consumers' health., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The distribution of pathogenic Legionella in the environmental soil and water of China has not been documented yet. In this study, Legionella was detected in 129 of 575 water (22.43%) and 41 of 442 soil samples (9.28%) by culture. Twelve Legionella species were identified, of which 11 were disease-associated. Of the Legionella -positive samples, 109 of 129 (84.50%) water and 29 of 41 (70.73%) soil were positive for L. pneumophila, which accounted for about 75% of Legionella isolates in both water and soil, suggesting L. pneumophila was the most frequent species. Soil showed a higher diversity of Legionella spp. as compared with water (0.6279 versus 0.4493). In contrast, serogroup (sg) 1 was more prevalent among L. pneumophila isolates from water than from soil (26.66% versus 12.21%). Moreover, many disease-associated sequence types (STs) of L. pneumophila were found in China. Intragenic recombination was acting on L. pneumophila from both water and soil. Phylogeny, population structure, and molecular evolution analyses revealed a probable existence of L. pneumophila isolates with a special genetic background that is more adaptable to soil or water sources and a small proportion of genetic difference between water and soil isolates. The detection of viable, clinically relevant Legionella demonstrates soil as another source for harboring and dissemination of pathogenic Legionella bacteria in China. Future research should assess the implication in public health with the presence of Legionella in the soil and illustrate the genetic and pathogenicity difference of Legionella between water and soil, particularly the most prevalent L. pneumophila. IMPORTANCE Pathogenic Legionella spp. is the causative agent of Legionnaires' disease (LD), and L. pneumophila is the most common one. Most studies have focused on L. pneumophila from water and clinical samples. However, the soil is another important reservoir for this bacterium, and the distribution of Legionella spp. in water and soil sources has not been compared and documented in China yet. Discovering the distribution of Legionella spp. and L. pneumophila in the two environments may help a deep understanding of the pathogenesis and molecular evolution of the bacterium. Our research systematically uncovered the distributions of Legionella spp. in different regions and sources (e.g., water and soil) of China. Moreover, phylogeny, population structure, and molecular evolution study revealed the possible existence of L. pneumophila with a special genetic background that is more adaptable to soil or water sources, and genetic difference may exist.

Background: An increasing severity of extreme storms and more intense seasonal flooding are projected consequences of climate change in the United States. In addition to the immediate destruction caused by storm surges and catastrophic flooding, these events may also increase the risk of infectious disease transmission. We aimed to determine the association between extreme and seasonal floods and hospitalizations for Legionnaires' disease in 25 US states during 2000-2011., Methods: We used a nonparametric bootstrap approach to examine the association between Legionnaires' disease hospitalizations and extreme floods, defined by multiple hydrometeorological variables. We also assessed the effect of extreme flooding associated with named cyclonic storms on hospitalizations in a generalized linear mixed model (GLMM) framework. To quantify the effect of seasonal floods, we used multi-model inference to identify the most highly weighted flood-indicator variables and evaluated their effects on hospitalizations in a GLMM., Results: We found a 32% increase in monthly hospitalizations at sites that experienced cyclonic storms, compared to sites in months without storms. Hospitalizations in months with extreme precipitation were in the 89 th percentile of the bootstrapped distribution of monthly hospitalizations. Soil moisture and precipitation were the most highly weighted variables identified by multi-model inference and were included in the final model. A 1-standard deviation (SD) increase in average monthly soil moisture was associated with a 49% increase in hospitalizations; in the same model, a 1-SD increase in precipitation was associated with a 26% increase in hospitalizations., Conclusions: This analysis is the first to examine the effects of flooding on hospitalizations for Legionnaires' disease in the United States using a range of flood-indicator variables and flood definitions. We found evidence that extreme and seasonal flooding is associated with increased hospitalizations; further research is required to mechanistically establish whether floodwaters contaminated with Legionella bacteria drive transmission., (© 2022. The Author(s).)

Legionella pneumophila (L. pneumophila) is one of the main pathogens, causing pneumonia and respiratory tract infections, especially in patients with ventilator-associated pneumonia (VAP). This study aimed to approve the hypothesis that the serogroup distribution of L. pneumophila isolates from patients is correlated with Legionella strains in the environment. A total of 280 bronchoalveolar lavage (BAL) samples from VAP patients admitted to the intensive care unit (ICU) as well as 116 water samples from different sources in four hospitals in Tehran, Iran, were evaluated for the presence of L. pneumophila infection by culture, nested polymerase chain reaction (PCR), real-time PCR, and sequencing for genetic diversity. The molecular and culture methods found 24 (8.6%) and 5 (1.8%) samples to be positive for L. pneumophila in VAP patients, while they found 23 (19.8%) and 8 (6.9%) positive samples in water resources, respectively. The sequencing results indicated that all positive clinical samples and 14 (60.8%) environmental samples were belonged to L. pneumophila serogroup 1. Smoking, age, length of ICU stay, and duration of ventilator use had strong relationship with L. pneumophila infectivity. In conclusion, this is the first report from Iran to determine minor differences in the serogroup distribution of environmental and clinical strains. However, further studies are needed to confirm this relationship in different regions of Iran., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Legionnaires' disease is an atypical pneumonia caused by inhaling small droplets of water containing the bacterium Legionella spp. In newborns, it is a rare event, usually associated with water births and the use of air conditioning systems or air humidifiers. A nosocomial outbreak of Legionnaires' disease in the maternity ward of a secondary-care hospital in Arandjelovac, Serbia is described.Two male newborns were found to be infected with Legionnella pneumophila . On Days 7 and 6 of life, respectively, they were transferred to a tertiary-care hospital with signs of severe pneumonia which was radiologically confirmed. L. pneumophila was detected in tracheal secretions from both infants by RT-PCR, and its antigens were also positive in urine samples. The source of infection in the secondary-care hospital was the internal hot water heating system, and the main contributory factor to the emergence of the infection was the low temperature of the hot water which did not kill the bacteria during the available exposure time.These two cases highlight the importance of being cautious about possible Legionnaires' disease in maternity wards with outdated or irregularly maintained internal water supply systems. The adoption of official guidelines for the control and regular maintenance of water supply systems, including the multidisciplinary cooperation of all relevant parties, forms the basis for direct monitoring for Legionella and the prevention of new outbreaks. Abbreviations: BCYE: buffered charcoal yeast extract agar; GVPC: glycine vancomycin polymyxin cycloheximide agar; LD - Legionnaires' disease; TR-PCR: Reverse transcription polymerase chain reaction.

BackgroundLegionnaires' disease is a respiratory illness often associated with hotels and travel. Spain is a major tourist destination and one of the European countries with most cases of Legionnaires' disease , both community- and travel-associated. However, the prevalence of Legionella in tourist facilities is unknown.AimThe present investigation aimed to survey the tourist facilities in the Balearic Islands, Spain, for Legionella prevalence.MethodsWe visited tourist facilities in the Balearic Islands in two different periods (2006-2010 and 2015-2018) and took water samples following national and international guidelines. Legionella was investigated by culture methods following international standards (ISO 11731:1998).ResultsWe evaluated 13,472 samples from 465 facilities. Bacteria of the Legionella genus were detected in 65.4% of the surveyed facilities. Contamination of the facilities was significantly higher during the second decade (54.5 vs 78.6%). The most frequent colonisers were L. pneumophila serogroup 2-14. We detected the pathogen in 15.9% and 6.9% of hot and cold water distribution systems samples, respectively. The Legionella contamination rate in cold water systems samples was higher when free chlorine levels were < 0.2 mg/L and at > 25 °C temperatures, while in the hot water systems samples, the contamination rate was higher at < 50 °C. Of the samples from hot tubs, 10.9% were contaminated.Conclusion Legionella prevalence in hotels in the Balearic Islands was high but the contamination rates depended on the installations. Corrective measures are still needed to improve Legionella control.

Sporadic Legionnaires' disease is frequently detected in commercial truck drivers. We report 2 sporadic cases of this disease in Barcelona, Spain, that occurred during December 2019 and September 2020. Laboratory findings were consistent with windshield wiper fluid without added screen wash as a possible source of infection for both cases.

Background and Aim: In order to cope with the requirements of COVID-19 pandemic and prevent overwhelming of the healthcare systems, during 2020 social distancing measures were proposed, and generalized lockdown. Aim of our study is to ascertain whether non-pharmaceutical intervention did have any impact on the epidemiology of Legionnaires' disease (LD), a respiratory infectious disease without interhuman spreading., Methods: Official national reports from 4 index countries in European Union (i.e. Germany, France, Italy, and Spain) were retrieved. The study included all cases notified during 2020 COVID-19 outbreak, versus the cases referred during the same period in 2019. Subgroup analyses for hospital-associated and travel-associated LD cases, as well as for lethality estimates were performed., Results: A sustained drop for incidence rate was confirmed, at EU-level (3.5 per 100,000 vs. 5.3 per 100,000) as well as in the national estimates. The decrease was particularly evident in Italy (RR 0.880, 95%CI 0.839 to 0.905), despite a transient surge in notification rates during the month of June, 2020. Subgroup analyses demonstrated a fall in travel-associated cases (-66.8% at EU level), while hospital-associated cases decreased in absolute number when compared to 2019, but where substantially stable in terms when compared to EU estimates. While Case Fatality Ratio increased in comparison with 2019, no significant trend was similarly identified in comparison to EU estimates.  Conclusions. Lockdown measures have impacted on the epidemiology of LD in Europe during 2020, but some heterogeneities were identified both across the assessed countries, and the various subgroup. Even though the absolute number of total cases did substantially decrease in 2020 compared to 2019, the effect of non-pharmaceutical interventions was mostly indirect, through a reduced interaction of individuals with environments at potentially high-risk for human infections (e.g. hospitals, accommodation sites, etc.).

Legionella pneumophila serogroup 1 (Lp1) sequence type (ST) 23 is one of the most commonly detected STs in Italy where it currently causes all investigated outbreaks. ST23 has caused both epidemic and sporadic cases between 1995 and 2018 and was analysed at genomic level and compared with ST23 isolated in other countries to determine possible similarities and differences. A core genome multi-locus sequence typing (cgMLST), based on a previously described set of 1,521 core genes, and single-nucleotide polymorphisms (SNPs) approaches were applied to an ST23 collection including genomes from Italy, France, Denmark and Scotland. DNAs were automatically extracted, libraries prepared using NextEra library kit and MiSeq sequencing performed. Overall, 63 among clinical and environmental Italian Lp1 isolates and a further seven and 11 ST23 from Denmark and Scotland, respectively, were sequenced, and pangenome analysed. Both cgMLST and SNPs analyses showed very few loci and SNP variations in ST23 genomes. All the ST23 causing outbreaks and sporadic cases in Italy and elsewhere, were phylogenetically related independent of year, town or country of isolation. Distances among the ST23s were further shortened when SNPs due to horizontal gene transfers were removed. The Lp1 ST23 isolated in Italy have kept their monophyletic origin, but they are phylogenetically close also to ST23 from other countries. The ST23 are quite widespread in Italy, and a thorough epidemiological investigation is compelled to determine sources of infection when this ST is identified in both LD sporadic cases and outbreaks., (© 2022 Ricci et al.)

Reported Legionnaires' disease (LD) cases began increasing in the United States in 2003 after relatively stable numbers for >10 years; reasons for the rise are unclear. We compared epidemiologic patterns associated with cases reported to the Centers for Disease Control and Prevention before and during the rise. The age-standardized average incidence was 0.48 cases/100,000 population during 1992-2002 compared with 2.71 cases/100,000 in 2018. Reported LD incidence increased in nearly every demographic, but increases tended to be larger in demographic groups with higher incidence. During both periods, the largest number of cases occurred among White persons, but the highest incidence was in Black or African American persons. Incidence and increases in incidence were generally largest in the East North Central, Middle Atlantic, and New England divisions. Seasonality was more pronounced during 2003-2018, especially in the Northeast and Midwest. Rising incidence was most notably associated with increasing racial disparities, geographic focus, and seasonality.

Legionella is an opportunistic premise plumbing pathogen and causative agent of a severe pneumonia called Legionnaires' Disease (LD). Cases of LD have been on the rise in the U.S. and globally. Although Legionella was first identified 45 years ago, it remains an 'emerging pathogen." Legionella is part of the normal ecology of a public water system and is frequently detected in regulatory-compliant drinking water. Drinking water utilities, regulators and public health alike are increasingly required to have a productive understanding of the evolving issues and complex discussions of the contribution of the public water utility to Legionella exposure and LD risk. This review provides a brief overview of scientific considerations important for understanding this complex topic, a review of findings from investigations of public water and LD, including data gaps, and recommendations for professionals interested in investigating public water utilities. Although the current literature is inconclusive in identifying a public water utility as a sole source of an LD outbreak, the evidence is clear that minimizing growth of Legionella in public water utilities through proper maintenance and sustained disinfectant residuals, throughout all sections of the water utility, will lead to a less conducive environment for growth of the bacteria in the system and the buildings they serve., (Copyright © 2021 Elsevier GmbH. All rights reserved.)

Incidence of Legionnaires' disease is increasing, particularly in the Mid-Atlantic states in the United States; since 2015, New Jersey has documented ≈250-350 legionellosis cases per year. We used SaTScan software to develop a semiautomated surveillance tool for prospectively detecting legionellosis clusters in New Jersey. We varied temporal window size and baseline period to evaluate optimal parameter selections. The surveillance system detected 3 community clusters of Legionnaires' disease that were subsequently investigated. Other, smaller clusters were detected, but standard epidemiologic data did not identify common sources or new cases. The semiautomated processing is straightforward and replicable in other jurisdictions, likely by persons with even basic programming skills.

Denmark has one of the highest Legionnaires' disease notification rates within Europe, averaging 4.7 cases per 100,000 population annually (2017 to 2020). The relatively high incidence of disease is not uniform across the country, and approximately 70% of all domestically acquired cases in Denmark are caused by Legionella pneumophila (LP) strains that are considered less virulent. The aim of this study was to investigate if colonization rates, levels of colonization, and/or types of LP present in hot water systems were associated with geographic differences in Legionnaires' disease incidence. Domestic water systems from four cities in Denmark were analyzed via culture and qPCR. Serogrouping and sequence typing was performed on randomly selected isolates. Single nucleotide polymorphism was used to identify clonal relationship among isolates from the four cities. The results revealed a high LP colonization rate from 68% to 87.5% among systems, composed primarily of non-serogroup 1. LP serogroup 1 reacting with the monoclonal antibody (MAb) 3/1 was not identified in any of the systems tested, while MAb 3/1 negative serogroup 1 strains were isolated from 10 systems (9.6%). We hypothesize that a combination of factors influences the incidence rate of LD in each city, including sequence type and serogroup distribution, colonization rate, concentration of Legionella in Pre-flush and Flush samples, and potentially building characteristics such as water temperature measured at the point of use.

Legionnaires' disease (LD) ( Legionella ) is a common cause of community-acquired pneumonia (CAP) in those requiring hospitalization. Geographical variation in the importance of Legionella species as an aetiologic agent of CAP is poorly understood. We performed a systematic review and meta-analysis of population-based observational studies that reported the proportion of Legionella infection in patients with CAP (1 January 1990 to 31 May 2020). Using five electronic databases, articles were identified, appraised and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Univariate and multivariate meta-regression analyses were conducted using study design, WHO region, study quality and healthcare setting as the explanatory variables. We reviewed 2778 studies, of which 219 were included in the meta-analysis. The mean incidence of CAP was 46.7/100,000 population (95% CI: 46.6-46.8). The mean proportion of Legionella as the causative agent for CAP was 4.6% (95% CI: 4.4 to 4.7). Consequently, the mean Legionella incidence rate was 2.8/100,000 population (95% CI: 2.7-2.9). There was significant heterogeneity across all studies I 2 = 99.27% ( p < 0.0001). After outliers were removed, there was a decrease in the heterogeneity ( I 2 = 43.53%). Legionella contribution to CAP has a global distribution. Although the rates appear highest in high income countries in temperate regions, there are insufficient studies from low- and middle-income countries to draw conclusions about the rates in these regions. Nevertheless, this study provides an estimate of the mean incidence of Legionella infection in CAP, which could be used to estimate the regional and global burden of LD to support efforts to reduce the impact of this infection as well as to fill important knowledge gaps.

Legionella pneumophila widely exists in natural and artificial water environments, which enables it to infect people. L. pneumophila infection causes Legionnaires' disease (LD), which is a significant but relatively uncommon respiratory infection. Approximately 90% of LD is caused by L. pneumophila serogroup 1 (Lp1). Meteorological conditions may affect the infectivity and virulence of Lp1, but the exact relationship between them is still unclear. In this study, we evaluated the virulence of Lp1 by screening of total 156 Lp1 strains isolated from cooling tower water in different regions of China by detecting their abilities to activate NF-κB signaling pathway in vitro . In addition, we screened the distribution of some selected virulence genes in these strains. The virulence, virulence gene distribution, and the meteorological factors were analyzed. We found that both the virulence and the distribution of virulence genes had a certain regional and meteorological correlation. Although the loss of several virulence genes showed significant effects on the virulence of Lp1 strains, the distribution of virulence genes had very limited effects on the virulence of Lp1. IMPORTANCE LD is likely to be underrecognized in many countries. Due to the widespread existence of L. pneumophila in natural and artificial water environments and to the lack of cross-protection against different strains, L. pneumophila is a potentially serious threat to human health. Therefore, effective monitoring of the virulence of L. pneumophila in the water environment is very important to prevent and control the prevalence of LD. Understanding the virulence of L. pneumophila can not only help us to predict the risk of possible outbreaks in advance but can also enable more targeted clinical treatment. This study highlights the importance of understanding the epidemiology and ecology of L. pneumophila isolated from public facilities in terms of public health and biology. Due to the potential for water sources to harbor and disseminate L. pneumophila and to the fact that geographical conditions influence the virulence of L. pneumophila, timely and accurate L. pneumophila virulence surveillance is urgently needed.

An outbreak of Legionnaires' disease affected 18 people in Montpellier, a town of the south of France, between December 2016 and July 2017. All cases were diagnosed by a positive urinary antigen test. No deaths were reported. Epidemiological, environmental and genomic investigations (nested Sequence-Based Typing (nSBT) and whole genome sequencing) were undertaken. For the cases for which we had information, four had a new isolate (ST2471), one had a different new isolate (ST2470), one had a genomic pattern compatible with the ST2471 identified by nSBT ( fla A = 3), and one had a genomic pattern not compatible with two previous identified STs ( pil E = 6). The analysis conducted on the pool of an aquatic therapy center revealed seven isolates of Legionella pneumophila . Whole genome analysis confirmed the link between the environmental and clinical isolates for both ST2470 and ST2471. As the outbreak occurred slowly, with several weeks between new cases, it was not possible to immediately identify a common source. The sixth case was the first to report having aquatic therapy care. Of the 18 cases, eight had attended the aquatic therapy center and the other 10 were inhabitants who lived, worked or walked close to the center. The main cause for this outbreak was the lack of facility maintenance. This investigation highlights the risk to public health of aquatic therapy centers for users and nearby populations, and emphasizes the need for risk reduction measures with specific guidelines to improve health and safety in aquatic facilities.

Legionellae are gram-negative bacteria most commonly found in freshwater ecosystems and purpose-built water systems. In humans, the bacterium causes Legionnaires' disease (LD) or a Pontiac fever. In this study, the different waters (drinking water, pool water, cooling towers) in which Legionella pneumophila has been isolated were studied to assess the possible risk of bacterial spreading in the population. The influence of physical and chemical parameters, and interactions with Acanthamoeba castellanii on L. pneumophila , were analyzed by Heterotrophic Plate Count, the Colony-forming units (CFU) methods, transmission electron microscopy (TEM), and Sequence-Based Typing (SBT) analysis. During the study period (2013-2019), a total of 1932 water samples were analyzed, with the average annual rate of Legionella -positive water samples of 8.9%, showing an increasing trend. The largest proportion of Legionella -positive samples was found in cooling towers and rehabilitation centers (33.9% and 33.3%, respectively). Among the isolates, L. pneumophila SGs 2-14 was the most commonly identified strain (76%). The survival of Legionella was enhanced in the samples with higher pH values, while higher electrical conductivity, nitrate, and free residual chlorine concentration significantly reduced the survival of Legionella. Our results show that growth in amoeba does not affect the allelic profile, phenotype, and morphology of the bacterium but environmental L. pneumophila becomes more resistant to pasteurization treatment.

The article discusses main directions and stages of the 45 years of Legionnaires disease study. Analysis of epidemiology and laboratory diagnostics of infection show as unknown until 1976 microorganism occupied a notable niche in the etiology of severe pneumonia. Control and monitoring of potential dangerous water systems, generating water aerosol containing Legionella in high concentration, plays a major role in the prevention of Legionnaires disease.

Emerging evidence shows co-infection with atypical bacteria in coronavirus disease 2019 (COVID-19) patients. Respiratory illness caused by atypical bacteria such as Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila may show overlapping manifestations and imaging features with COVID-19 causing clinical and laboratory diagnostic issues. We conducted a prospective study to identify co-infections with SARS-CoV-2 and atypical bacteria in an Indian tertiary hospital. From June 2020 to January 2021, a total of 194 patients with laboratory-confirmed COVID-19 were also tested for atypical bacterial pathogens. For diagnosing M. pneumoniae, a real-time polymerase chain reaction (PCR) assay and serology (IgM ELISA) were performed. C. pneumoniae diagnosis was made based on IgM serology. L. pneumophila diagnosis was based on PCR or urinary antigen testing. Clinical and epidemiological features of SARS-CoV-2 and atypical bacteria-positive and -negative patient groups were compared. Of the 194 patients admitted with COVID-19, 17 (8.8%) were also diagnosed with M. pneumoniae (n = 10) or C. pneumoniae infection (n = 7). Confusion, headache, and bilateral infiltrate were found more frequently in the SARS CoV-2 and atypical bacteria co-infection group. Patients in the M. pneumoniae or C. pneumoniae co-infection group were more likely to develop ARDS, required ventilatory support, had a longer hospital length of stay, and higher fatality rate compared to patients with only SARS-CoV-2. Our report highlights co-infection with bacteria causing atypical pneumonia should be considered in patients with SARS-CoV-2 depending on the clinical context. Timely identification of co-existing pathogens can provide pathogen-targeted treatment and prevent fatal outcomes of patients infected with SARS-CoV-2 during the current pandemic., (© 2021 Wiley Periodicals LLC.)

Legionella pneumophila is the cause of Legionnaires' disease, a life-threatening pneumonia that occurs after inhalation of aerosolized water containing the bacteria. Legionella growth occurs in stagnant, warm-to-hot water (77°F-113°F) that is inadequately disinfected. Piped hot spring water in Hot Springs National Park, Arkansas, USA, has naturally high temperatures (>135°F) that prevent Legionella growth, and Legionnaires' disease has not previously been associated with the park or other hot springs in the United States. During 2018-2019, Legionnaires' disease occurred in 5 persons after they visited the park; 3 of these persons were potentially exposed in spa facilities that used untreated hot spring water. Environmental testing revealed Legionella bacteria in piped spring water, including 134°F stagnant pipe water. These findings underscore the importance of water management programs to reduce Legionella growth in plumbing through control activities such as maintaining hot water temperatures, reducing stored water age, and ensuring adequate water flow.

Legionellosis is a severe pneumonia caused by the inhalation of aerosols containing Legionella, Gram-negative bacteria present in the water systems of touristic-recreational facilities. The purpose of this study was to develop a scoring tool to predict the risk of both environmental contamination and Legionnaires' disease cases in such facilities in the Apulia region of southern Italy. We analyzed 47 structural and management parameters/risk factors related to the buildings, water systems, and air conditioning at the facilities. A Poisson regression model was used to compute an overall risk score for each facility with respect to three outcomes: water samples positive for Legionella (risk score range: 7-54), water samples positive for Legionella with an average load exceeding 1000 colony-forming units per liter (CFU/L) (risk score range: 22-179,871), and clinical cases of Legionnaire's disease (risk score range: 6-31). The cut-off values for three outcomes were determined by receiver operating characteristic curves (first outcome, samples positive for Legionella in a touristic-recreational facility: 19; second outcome, samples positive for Legionella in a touristic-recreational facility with an average load exceeding 1000 CFU/L: 2062; third outcome, clinical cases of Legionnaire's disease in a touristic-recreational facility: 22). Above these values, there was a significant probability of observing the outcome. We constructed this predictive model using 70% of a large dataset (18 years of clinical and environmental surveillance) and tested the model on the remaining 30% of the dataset to demonstrate its reliability. Our model enables the assessment of risk for a touristic facility and the creation of a conceptual framework to link the risk analysis with prevention measures., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Japan experienced a heavy rainfall event from June 28 to July 8, 2018, and many casualties were caused by both heavy rainfall and flooding. Few studies have investigated patients' characteristics and the causative pathogens of community-acquired pneumonia before and after heavy rainfall events. The aim of the present study was to evaluate the causative pathogens and clinical characteristics of hospitalized patients with community-acquired pneumonia before and after the heavy rainfall event using prospective cohort data., Methods: The study was divided into two periods: July to November 2013-2017 (before heavy rainfall) and July to November 2018 (after heavy rainfall). The patients' clinical characteristics and causative pathogens before and after the heavy rainfall were investigated. Regarding the causative pathogens, adjustments were made for precipitation and seasonal patterns., Results: There were no significant differences in the number and clinical characteristics of patients before and after heavy rainfall. However, the frequency of Legionella pneumonia was significantly higher after than before the heavy rainfall event (8.9% vs 3.0%, P = 0.02) and remained significant after adjusting for precipitation and season. Three of 7 Legionella pneumonia patients engaged in reconstruction work and 2 Legionella pneumonia patients had soil exposure., Conclusions: An increased risk of Legionella pneumonia after not only rainfall and serious flooding, but also following recovery work or soil exposure should be considered., (Copyright © 2021 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Introduction: We performed SBT (sequence-based typing) on clinical and environmental Legionellapneumophila isolates in Shenyang (China). We analyzed and compared the results with those obtained by PFGE (pulsed field gel electrophoresis)., Methods: Twenty-two L. pneumophila isolates were collected from two patients with L. pneumophila infection, two hospitals, and 13 office buildings. There were two clinical isolates, one strain isolated from domestic tap water, another from shower water and 18 strains from cooling tower water. All these isolates were analyzed by SBT and PFGE methods., Results: The 22 isolates were divided into 7 types by SBT. Five isolates belonged to novel sequence types (ST2345, ST2344, ST2406, ST2407, and ST2408) and one isolate belonged to ST328. The STs were not obtained for two of the isolates. The remaining 14 isolates belonged to ST1. PFGE typing divided the 22 isolates into 14 pulsotypes. The main pulsotype was SYC, which included seven isolates., Conclusion: Both typing methods showed that predominant clonal lines exist in the Shenyang region, with high levels of genetic polymorphisms. Five novel STs were identified, indicating a unique genetic composition of L. pneumophila strains in this region, which are significantly different from those found in other environmental water systems in the world., (Copyright © 2020 The Author(s). Published by Elsevier España, S.L.U. All rights reserved.)

Legionella pneumophila is an opportunistic bacterial respiratory pathogen that is one of the leading causes of drinking water outbreaks in the United States. Dental offices pose a potential risk for inhalation or aspiration of L. pneumophila due to the high surface area to volume ratio of dental unit water lines-a feature that is conducive to biofilm growth. This is coupled with the use of high-pressure water devices (e.g., ultrasonic scalers) that produce fine aerosols within the breathing zone. Prior research confirms that L. pneumophila occurs in dental unit water lines, but the associated human health risks have not been assessed. We aimed to: (1) synthesize the evidence for transmission and management of Legionnaires' disease in dental offices; (2) create a quantitative modeling framework for predicting associated L. pneumophila infection risk; and (3) highlight influential parameters and research gaps requiring further study. We reviewed outbreaks, management guidance, and exposure studies and used these data to parameterize a quantitative microbial risk assessment (QMRA) model for L. pneumophila in dental applications. Probabilities of infection for dental hygienists and patients were assessed on a per-exposure and annual basis. We also assessed the impact of varying ventilation rates and the use of personal protective equipment (PPE). Following an instrument purge (i.e., flush) and with a ventilation rate of 1.2 air changes per hour, the median per-exposure probability of infection for dental hygienists and patients exceeded a 1-in-10,000 infection risk benchmark. Per-exposure risks for workers during a purge and annual risks for workers wearing N95 masks did not exceed the benchmark. Increasing air change rates in the treatment room from 1.2 to 10 would achieve an ∼85% risk reduction, while utilization of N95 respirators would reduce risks by ∼95%. The concentration of L. pneumophila in dental unit water lines was a dominant parameter in the model and driver of risk. Future risk assessment efforts and refinement of microbiological control protocols would benefit from expanded occurrence datasets for L. pneumophila in dental applications.

Legionnaires Disease incidence has risen in the Netherlands in recent years. For the majority of the cases, the source of infection is never identified. Two Dutch wastewater treatment plants (WWTPs) have previously been identified as source of outbreaks of Legionnaires Disease (LD) among local residents. The objective of this study is to examine if LD patients in the Netherlands are more exposed to aerosols originating from WWTPs than controls., Methods: An atmospheric dispersion model was used to generate nationwide exposure maps of aerosols from 776 WWTPs in the Netherlands. Municipal sewage treatment plants and industrial WWTPs were both included. Exposure of LD cases and controls at the residential address was compared, in a matched case-control design using a conditional logistic regression. Cases were notified LD cases with onset of disease in the period 2013-2018 in the Netherlands (n = 1604)., Results: Aerosols dispersed over a large part of the Netherlands, but modelled concentrations are estimated to be elevated in close proximity to WWTPs. A statistically significant association was found between LD and the calculated annual average aerosol concentrations originating from WWTPs (odds-ratio: 1.32 (1.06-1.63)). This association remained significant when the two outbreak-related WWTPs were removed from the analysis (odds-ratio: 1.28 (1.03-1.58))., Conclusion: LD cases were more exposed to aerosols from WWTPs than controls. This indicates that exposure to aerosols dispersed from WWTPs caused Legionnaires Disease in residents living near WWTPs in the period 2013-2018. In order to investigate which characteristics of WWTPs are associated with an increased LD risk, the WWTP database should be updated and more data is needed on the presence and survival of aerosolized Legionella bacteria to improve the Legionella dispersion modelling. Furthermore, it is recommended to further investigate how aerosol dispersion of WWTPs can effectively be reduced in order to reduce the potential health risk., (Copyright © 2021 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Background: An outbreak of Legionella pneumonia occurred at a university hospital using copper-silver ionization for potable water disinfection. We present the epidemiological and laboratory investigation of the outbreak, and associated case-control study., Methods: Cases were defined by syndrome compatible with Legionella pneumonia with laboratory-confirmed Legionella infection. The water circuit and disinfection system were assessed, and water samples collected for Legionella culture. Whole genome multi-locus sequence typing (wgMLST) was used to compare the genetic similarity of patient and environmental isolates. A case-control study was conducted to identify risk factors for Legionella pneumonia., Results: We identified 13 cases of hospital-acquired Legionella. wgMLST revealed >99.9% shared allele content among strains isolated from clinical and water samples. Smoking (P= .008), steroid use (P= .007), and documented shower during hospitalization (P= .03) were risk factors for Legionella pneumonia on multivariable analysis. Environmental assessment identified modifications to the hospital water system had occurred in the month preceding the outbreak. Multiple mitigation efforts and application of point of use water filters stopped the outbreak., Conclusions: Potable water system Legionella colonization occurs despite existing copper-silver ionization systems, particularly after structural disruptions. Multidisciplinary collaboration and direct monitoring for Legionella are important for outbreak prevention. Showering is a modifiable risk factor for nosocomial Legionella pneumonia. Shower restriction and point-of-use filters merit consideration during an outbreak., (Copyright © 2021 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

Since 1978, the New York State Department of Health's public health laboratory, Wadsworth Center (WC), in collaboration with epidemiology and environmental partners, has been committed to providing comprehensive public health testing for Legionella in New York. Statewide, clinical case counts have been increasing over time, with the highest numbers identified in 2017 and 2018 (1,022 and 1,426, respectively). Over the course of more than 40 years, the WC Legionella testing program has continuously implemented improved testing methods. The methods utilized have transitioned from solely culture-based methods for organism recovery to development of a suite of reference testing services, including identification and characterization by PCR and pulsed-field gel electrophoresis (PFGE). In the last decade, whole-genome sequencing (WGS) has further refined the ability to link outbreak strains between clinical specimens and environmental samples. Here, we review Legionnaires' disease outbreak investigations during this time period, including comprehensive testing of both clinical and environmental samples. Between 1978 and 2017, 60 outbreaks involving clinical and environmental isolates with matching PFGE patterns were detected in 49 facilities from the 157 investigations at 146 facilities. However, 97 investigations were not solved due to the lack of clinical or environmental isolates or PFGE matches. We found 69% of patient specimens from New York State (NYS) were outbreak associated, a much higher rate than observed in other published reports. The consistent application of new cutting-edge technologies and environmental regulations has resulted in successful investigations resulting in remediation efforts. IMPORTANCE Legionella, the causative agent of Legionnaires' disease (LD), can cause severe respiratory illness. In 2018, there were nearly 10,000 cases of LD reported in the United States (https://www.cdc.gov/legionella/fastfacts.html; https://wonder.cdc.gov/nndss/static/2018/annual/2018-table2h.html), with actual incidence believed to be much higher. About 10% of patients with LD will die, and as high as 90% of patients diagnosed will be hospitalized. As Legionella is spread predominantly through engineered building water systems, identifying sources of outbreaks by assessing environmental sources is key to preventing further cases LD.

Legionnaires' disease (LD) is a severe pneumonia caused by bacteria belonging to the genus Legionella . This is a major public health concern and infections are steadily increasing worldwide. Several sources of infection have been identified, but they have not always been linked to human isolates by molecular match. The well-known Legionella contamination of private homes has rarely been associated with the acquisition of the disease, although some patients never left their homes during the incubation period. This study demonstrated by genomic matching between clinical and environmental Legionella isolates that the source of an LD cluster was a private building. Monoclonal antibodies and sequence-based typing were used to type the isolates, and the results clearly demonstrated the molecular relationship between the strains highlighting the risk of contracting LD at home. To contain this risk, the new European directive on the quality of water intended for human consumption has introduced for the first time Legionella as a microbiological parameter to be investigated in domestic water systems. This should lead to a greater attention to prevention and control measures for domestic Legionella contamination and, consequently, to a possible reduction in community acquired LD cases.

Introduction and Objective: Legionnaires' disease, which is a waterborne disease leading to pneumonia that can result in death, is one of the major health issues today. The study aims to carry out a three-year retrospective review of routine Legionella follow-up analyses in various samples taken mostly from hospitals in the province of Erzurum and nearby provinces, and to discover a the frequency of isolation of the agent and serogroups from each kind of media., Material and Methods: The study included a total of 2,025 water samples taken from hospitals, hotels, Turkish baths and shopping malls in Erzurum,and 13 nearby cities between 2016 and 2018. Samples were filtered by 0.45 μm-diameter membrane filter paper in the Public Health Laboratory of Erzurum and examined for L. pneumophila using culture method, according to the criteria set out in ISO 11731-2., Results: The presence of L. pneumophila was found in 65 of the 2,025 water samples taken in hospitals, and in none of 40 samples taken in hotels, Turkish baths and shopping malls. L. pneumophila serogroup 2-14 was detected in 46 (70.8%) of 65 samples found positive, whereas L. pneumophila serogroup 1 was detected in 18 (27.7%). Furthermore, both the L. pneumophila serogroup 2-14 and L. pneumophila serogroup 1 were detected simultaneously in one example (1.5%). The first three samples indicate that the highest positivity rates were in hot water taps (11.6%), hot water tanks (6.1%) and shower heads (4.8%)., Conclusions: The Prevalence rat of L. pneumophila was found to be quite low compared to other studies conducted in the western regions of Turkey. Legionella positivity was found to be higher in the hot water systems of hospitals and related points, compared to the other sample points.

BackgroundLegionnaires' disease (LD) incidence has been increasing in several European countries since 2011. Currently, Denmark is experiencing one of the highest annual incidences of LD despite its relatively cold climate and homogenous population, and the incidence differs notably across the country.AimWe sought to determine whether provincial differences in LD incidence are attributable to the age and sex distribution of the population, and to characterise the risk of LD by province and age group in Denmark.MethodsUsing national routine surveillance data for domestic LD cases collected between 2015 and 2018, we assessed the incidence of disease by province and year. Poisson regression models were fit to understand the risk of LD by year and province, as well as by 5-year age groups.ResultsIncidence of domestic LD increased 48% between 2015 and 2018 across Denmark. Some provinces continuously had a high incidence of disease, even after adjusting for yearly trends and the underlying population distribution. Variations in the proportion of the population aged 65 years and older were not responsible for the increase in disease in our analysis. Finally, incidence of disease increased with each 5-year age group in both men and women.ConclusionsThe relative differences in incidence between Danish provinces could not be explained by the age and sex distribution of the population, indicating that other factors must be responsible for the varying incidence across the country. These results may help inform trends in other countries in Europe also experiencing an unexplained high incidence of LD.

In September 2018 in Brescia province, northern Italy, an outbreak of Legionnaires' disease (LD) caused by Legionella pneumophila serogroup 2 ( Lp2 ) occurred. The 33 cases (two fatal) resided in seven municipalities along the Chiese river. All cases were negative by urinary antigen test (UAT) and most were diagnosed by real-time PCR and serology. In only three cases, respiratory sample cultures were positive, and Lp2 was identified and typed as sequence type (ST)1455. In another three cases, nested sequence-based typing was directly applied to respiratory samples, which provided allelic profiles highly similar to ST1455. An environmental investigation was undertaken immediately and water samples were collected from private homes, municipal water systems, cooling towers and the river. Overall, 533 environmental water samples were analysed and 34 were positive for Lp . Of these, only three samples, all collected from the Chiese river, were Lp2 ST1455. If and how the river water could have been aerosolised causing the LD cases remains unexplained. This outbreak, the first to our knowledge caused by Lp2 , highlights the limits of UAT for LD diagnosis, underlining the importance of adopting multiple tests to ensure that serogroups other than serogroup 1, as well as other Legionella species, are identified.

Background: American Thoracic Society/Infectious Diseases Society of America guidelines recommend against routine Legionella pneumophila testing, but recommend that hospitalized patients with community-acquired pneumonia receive empiric treatment covering Legionella. Testing, empiric treatment, and outcomes for patients with Legionella have not been well described., Research Question: Is testing for Legionella pneumophila appropriate, and could it impact treatment?, Study Design and Methods: We conducted a large retrospective cohort analysis using Premier Healthcare Database data from 2010 to 2015. We included adults with a principal diagnosis code for pneumonia (or a principal diagnosis of respiratory failure or sepsis with secondary diagnosis of pneumonia) if they also received treatment for pneumonia on hospital days 1-3. We categorized Legionella-tested patients by test result, identified patient characteristics associated with testing and test result, and examined seasonal and regional patterns of Legionella pneumonia (LP) diagnoses. Empiric therapy for LP was defined as a macrolide, quinolone, or doxycycline, administered on each of the first two hospital days., Results: Of 166,689 eligible patients, 43,070 (26%) were tested for Legionella, and 642 (1.5%) tested positive. Although only 36% of tests were ordered from June to October, 70% of positive test results occurred during this time. Only 30% of patients with hyponatremia, 32% with diarrhea, and 27% in the ICU were tested. Of patients with positive test results, 495 of 642 (77%) had received empiric Legionella therapy. Patients with LP did not have more severe presentation. They had more frequent late decompensation, but similar mortality to patients without LP., Interpretation: Legionella is an uncommon cause of community-acquired pneumonia, occurring primarily from late spring through early autumn. Testing is uncommon, even among patients with risk factors, and many patients with positive test results failed to receive empiric coverage for LP., (Copyright © 2020 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Background: Recent travel is associated with ~20% of reported Legionnaires' disease (LD) cases worldwide., Methods: We analyzed LD cases reported to the Centers for Disease Control and Prevention (CDC) during 2015-2016. Travel-associated cases met case criteria for confirmed LD in someone who spent ≥1 night away from home during the 10 days before symptom onset. Most analyses were limited to travel-associated, public accommodation stay (TAPAS) cases. We used reported travel dates to estimate the number of TAPAS cases acquired during travel., Results: Of 12,200 LD cases reported among U.S. residents, 12.3% were travel-associated; 8.7% were TAPAS. Median patient age for TAPAS cases was 61 years; 64.4% were male; 67.3% were white; 77.9% were non-Hispanic; 96.1% were hospitalized; 4.5% died. Among 887 TAPAS cases involving U.S. destinations, an estimated 29.8% were acquired during travel; 4.28 TAPAS cases were reported, and an estimated 1.10 TAPAS cases were acquired during travel, per 10,000,000 hotel room nights booked. Sixty-eight U.S. TAPAS clusters were detected., Conclusions: While acquisition during travel accounted for a relatively small proportion of all LD cases, clusters of TAPAS cases were frequently detected. Prompt notification of these cases to CDC facilitates cluster detection and expedites intervention., (Published by Elsevier Ltd.)

In early June 2018, an increase in non-travel-related cases of Legionella non- pneumophila Legionnaires' disease (LD) was observed in Sweden and a national outbreak investigation was started. Outbreak cases were defined as notified confirmed or probable cases of L. non- pneumophila LD, with symptom onset after 1 April 2018. From April to August 2018, 41 cases were reported, 30 of whom were identified as L. longbeachae. We conducted a case-control study with 27 cases and 182 matched controls. Results from the case-control study indicated that gardening and handling commercial bagged soil, especially dusty dry soil, were associated with disease. L. longbeachae was isolated in soils from cases' homes or gardens, but joint analysis of soil and human specimens did not identify any genetic clonality. Substantial polyclonality was noted between and within soil samples, which made finding a genetic match between soil and human specimens unlikely. Therefore, whole genome sequencing may be of limited use to confirm a specific soil as a vehicle of transmission for L. longbeachae. Handling soil for residential gardening was associated with disease and the isolation of L. longbeachae in different soils provided further evidence for Legionella non -pneumophila infection from soil.

Healthcare-related Legionnaires' disease has a devastating impact on high risk patients, with a case fatality rate of 30-50%. Legionella prevention and control in hospitals is therefore crucial. To control Legionella water colonisation in a hospital setting we evaluated the effect of pipeline improvements and temperature increase, analysing 237 samples over a 2-year period (first year: 129, second year: 108). In the first year, 25.58% of samples were positive for Legionella and 16.67% for amoeba. Assessing the distance of the points analysed from the hot water tank, the most distal points presented higher proportion of Legionella colonisation and lower temperatures (nearest points: 6.4% colonised, and temperature 61.4 °C; most distal points: 50% and temperature 59.1 °C). After the first year, the hot water system was repaired and the temperature stabilised. This led to a dramatic reduction in Legionella colonisation, which was negative in all the samples analysed; however, amoeba colonisation remained stable. This study shows the importance of keeping the temperature stable throughout the circuit, at around 60 °C. Special attention should be paid to the most distal points of the circuit; a fall in temperature at these weak points would favour the colonisation and spread of Legionella, because amoeba (the main Legionella reservoir) are not affected by temperature.

Legionnaires' disease, a severe lung infection caused by the bacterium Legionella pneumophila , occurs as single cases or in outbreaks that are actively tracked by public health departments. To determine the point source of an outbreak, clinical isolates need to be compared to environmental samples to find matching isolates. One confounding factor is the genome plasticity of L. pneumophila , making an exact sequence comparison by whole-genome sequencing (WGS) challenging. Here, we present a WGS analysis pipeline, LegioCluster, that is designed to circumvent this problem by automatically selecting the best matching reference genome prior to mapping and variant calling. This approach reduces the number of false-positive variant calls, maximizes the fraction of all genomes that are being compared, and naturally clusters the isolates according to their reference strain. Isolates that are too distant from any genome in the database are added to the list of candidate references, thereby creating a new cluster. Short insertions or deletions are considered in addition to single-nucleotide polymorphisms for increased discriminatory power. This manuscript describes the use of this automated and "locked down" bioinformatic pipeline deployed at the New York State Department of Health's Wadsworth Center for investigating relatedness between clinical and environmental isolates. A similar pipeline has not been widely available for use to support these critically important public health investigations., (Copyright © 2021 American Society for Microbiology.)

Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential cause of this infection. Legionellosis was first identified in 1977, and it is caused by Gram-negative bacteria belonging to the genus Legionella. Legionellosis remains an important public health threat, particularly in Japan, where the population is rapidly aging, thereby becoming more at risk of developing severe disease and accompanying life-threatening pneumonia. The bacteria are most commonly transmitted via the inhalation of contaminated aerosols produced and broadcast via water sprays, jets or mists. Infection can also occur via the aspiration of contaminated water or ice, or through inhalation of contaminated dust. Because the signs and symptoms of Legionnaires' disease (LD), as well as radiographic imaging are similar to pneumonia caused by other pathogens, a specific diagnostic test is required, such as a urine antigen detection test. Six clinical and laboratory parameters, a high body temperature, a non-productive cough, low serum sodium and platelet counts, and high lactate dehydrogenase (LDH) and c-reactive protein concentrations can be used to reliably predict the likelihood of LD. The first choices for chemotherapy are fluoroquinolone and macrolide antibiotic drugs. The main goals of LD prevention measures are 1) the prevention of microbial growth and biofilm formation, 2) the removal of all biofilm formed on equipment and in facilities, 3) minimizing aerosol splash and spread, and 4) minimizing bacterial contamination from external sources. It is apparent that, in Japan, where hot spring (onsen) bathing is common among aged people, strict regulations need to be in place - and enforced - to ensure that all Japanese onsens and spas provide a safe environment and undertake regular, effective infection control practices.

Legionnaires' disease and Pontiac fever are both diseases with important public health implications and require prompt and thorough responses to outbreaks for future prevention. Effective methods for defining, diagnosing, reporting and responding to legionellosis outbreaks ideally should be standardized across countries. Therefore, the European Union surveillance methods for countering Legionnaires' disease is a useful model especially for travel-associated Legionnaires' disease (TALD) cases which are on the rise. Multi-country surveillance in the EU and European Economic Area (EEA) has evolved since the first organizational efforts in the 1980's to the currently responsible, European Legionnaires' Disease Surveillance Network (ELDSNet). This chapter outlines the practices of the EU surveillance of Legionnaires' disease including their schemata, definitions, responsibilities of participating members, methods and the results of the data collected since the program's inception. Lastly, improvements must still be made as the incidence of Legionnaires' disease in the EU is likely underestimated due to underreporting and/or underdiagnosis. Nearly 70% of cases are reported from only four countries, France, Germany, Italy and Spain, which represent 50% of the EU population.

Through the use of published estimates of medical costs and new calculations of productivity losses, we estimate the lifetime economic burden of 2014 Legionnaires' disease cases in the United States at ≈$835 million. This total includes $21 million in productivity losses caused by absenteeism and $412 million in productivity losses caused by premature deaths.