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Background: The number of reported cases of Legionnaires' disease (LD) has risen markedly in Switzerland (6.5/100,000 inhabitants in 2021) and abroad over the last decade. Legionella, the causative agent of LD, are ubiquitous in the environment. Therefore, environmental changes can affect the incidence of LD, for example by increasing bacterial concentrations in the environment or by facilitating transmission., Objectives: The aim of this study is to understand the environmental determinants, in particular weather conditions, for the regional and seasonal distribution of LD in Switzerland., Methods: We conducted a series of analyses based on the Swiss LD notification data from 2017 to 2021. First, we used a descriptive and hotspot analysis to map LD cases and identify regional clusters. Second, we applied an ecological model to identify environmental determinants on case frequency at the district level. Third, we applied a case-crossover design using distributed lag non-linear models to identify short-term associations between seven weather variables and LD occurrence. Lastly, we performed a sensitivity analysis for the case-crossover design including NO 2 levels available for the year 2019., Results: Canton Ticino in southern Switzerland was identified as a hotspot in the cluster analysis, with a standardised notification rate of 14.3 cases/100,000 inhabitants (CI: 12.6, 16.0). The strongest association with LD frequency in the ecological model was found for large-scale factors such as weather and air pollution. The case-crossover study confirmed the strong association of elevated daily mean temperature (OR 2.83; CI: 1.70, 4.70) and mean daily vapour pressure (OR: 1.52, CI: 1.15, 2.01) 6-14 days before LD occurrence., Discussion: Our analyses showed an influence of weather with a specific temporal pattern before the onset of LD, which may provide insights into the effect mechanism. The relationship between air pollution and LD and the interplay with weather should be further investigated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Since the discovery of Legionnaires' disease (LD), limited progress has been made in understanding the epidemiology of sporadic cases of LD. Outbreaks have confirmed that air conditioning and potable water systems can be sources of community-acquired LD. However, studying the association between water quality and LD incidence has been challenging due to the heterogeneity of water systems across large geographic areas. Furthermore, although seasonal trends in incidence have been linked to increased rainfall and temperatures, the large geographic units have posed similar difficulties. To address this issue, a retrospective ecological study was conducted in Washington, DC, from 2001 to 2019. The study identified aseasonal pattern of LD incidence, with the majority of cases occurring between June and December, peaking in August, October, and November. Increased temperature was found to be associated with LD incidence. In surface water, higher concentrations of manganese, iron, and strontium were positively associated with LD, while aluminum and orthophosphate showed a negative association. Intreatment plant water, higher concentrations of total organic carbon, aluminum, barium, and chlorine were positively associated with LD, while strontium, zinc, and orthophosphate showed a negative association. The results for orthophosphates and turbidity were inconclusive, indicating the need for further research.

A number of studies suggest that meteorological conditions are related to the risk of Legionnaires' disease (LD) but the findings are not consistent. A systematic review was conducted to investigate the association of weather with sporadic LD and highlight the key meteorological conditions related to this outcome. PubMed, EMBASE, The Cochrane Library and OpenGrey were searched on 26-27 March 2020 without date, language or location restrictions. Key words included "legionellosis", "legionnaires' disease", combined with "meteorological conditions", "weather", "temperature", "humidity", "rain", "ultraviolet rays", "wind speed", etc. Studies were excluded if they did not examine the exposure of interest, the outcome of interest and their association or if they only reported LD outbreak cases. The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and it was registered in PROSPERO (#CRD42020168869). There were 811 articles, of which 17 were included in the review. The studies investigated different meteorological variables and most of them examined the combined effect of several variables. The most commonly examined factors were precipitation and temperature, followed by relative humidity. The studies suggested that increased precipitation, temperature and relative humidity were positively associated with the incidence of LD. There was limited evidence that higher wind speed, pressure, visibility, UV radiation and longer sunshine duration were inversely linked with the occurrence of LD. A period of increased but not very high temperatures, followed by a period of increased precipitation, favour the occurrence of LD. Increased awareness of the association of temperature and precipitation and LD occurrence among clinicians and public health professionals can improve differential diagnosis for cases of sporadic community-acquired pneumonia and at the same time contribute to improving LD surveillance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Legionnaire's disease is one of the major causes of community-acquired pneumonia and is occasionally complicated by neurological symptoms. However, reports of ocular lesions due to Legionnaire's disease are limited., Case Presentation: We report the case of a patient with Legionnaire's disease presenting as bilateral central scotomata due to retinal lesions. The patient consulted due to fever and bilateral central scotomata, as well as other extrapulmonary symptoms. Optical coherence tomography (OCT) showed bilateral accumulations of fluid under the retina, and the patient was diagnosed with bilateral exudative retinal detachment. Later, Legionnaire's disease was confirmed by pulmonary infiltrates on chest imaging and positive urinary antigen for Legionella pneumophila. After administration of antibiotics, the bilateral central scotomata and bilateral subretinal fluid accumulations completely resolved, as did the other extrapulmonary symptoms and the pulmonary infiltrates. Thus, the bilateral central scotomata due to exudative retinal detachment were thought to be caused by Legionnaire's disease., Conclusions: This case demonstrates that Legionnaire's disease can present as bilateral central scotomata. We may consider the possibility of extrapulmonary involvement complicating Legionnaire's disease when we encounter bilateral ocular lesions in patients with fever and pneumonia.

We herein report a case of fulminant Legionnaires' disease with autopsy findings in a patient on maintenance hemodialysis (HD). Chronic kidney disease is a strong risk factor for Legionnaires' disease, although there have been only a few reports in HD patients. Because most patients on HD are anuric, the use of rapid assay kits to detect antigens in urine samples for the diagnosis of Legionnaires' disease is not always feasible. We suggest the use of clinical predictive tools or the loop-mediated isothermal amplification (LAMP) method, which can be applied for anuric patients, such as those on HD, with pneumonia.

From 2011 through 2018, there was a notable increase in sporadic Legionnaires' disease in the state of Minnesota. Sporadic cases are those not associated with a documented outbreak. Outbreak-related cases are typically associated with a common identified contaminated water system; sporadic cases typically do not have a common source that has been identified. Because of this, it is hypothesised that weather and environmental factors can be used as predictors of sporadic Legionnaires' disease. An ecological design was used with case report surveillance data from the state of Minnesota during 2011 through 2018. Over this 8-year period, there were 374 confirmed Legionnaires' disease cases included in the analysis. Precipitation, temperature and relative humidity (RH) data were collected from weather stations across the state. A Poisson regression analysis examined the risk of Legionnaires' disease associated with precipitation, temperature, RH, land-use and age. A lagged average 14-day precipitation had the strongest association with Legionnaires' disease (RR 2.5, CI 2.1-2.9), when accounting for temperature, RH, land-use and age. Temperature, RH and land-use also had statistically significant associations to Legionnaires' disease, but with smaller risk ratios. This study adds to the body of evidence that weather and environmental factors play an important role in the risk of sporadic Legionnaires' disease. This is an area that can be used to target additional research and prevention strategies.

We herein report the case of a 62-year-old man diagnosed with Legionella pneumonia while engaged in recovery work in a flooded area after the Heavy Rain Event of July 2018 in Japan. The patient was intubated and maintained on mechanical ventilation and continuous hemodiafiltration. He was also administered antimicrobial therapy with ciprofloxacin and azithromycin. After 53 days in the hospital, he was discharged. It is important to recognize the risk of Legionella infection and to take measures to prevent it during recovery work that involves exposure to water and soil after a flood disaster.

This report describes the case of an 80-year-old man with culture-negative prosthetic valve endocarditis who ultimately was given a diagnosis of Legionella pneumophila endocarditis., (Copyright © 2019 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Objectives: Legionnaires' disease (LD), which is atypical pneumonia with a broad variety of clinical symptoms, can lead to death despite its low incidence. There are multiple risk factors for LD, yet little information is available concerning what kind of environmental factors are linked to higher risk of LD development. We have experienced a fatal case of LD, which occurred in a decontamination worker after the Fukushima nuclear disaster., Case: A 53-year-old Japanese male visited our hospital with symptoms of fever, vomiting, diarrhea, and altered mental status, but not with respiratory manifestations. He was engaged in decontamination work, which generally includes operations such as the removal of topsoil in mountainous areas and cleaning roads and roofs of residential buildings with high-pressure water. He was required to wear specific equipment to prevent radiation exposure, and lived in a workers' dormitory or shared house, thereby sharing spaces with other workers. Normal antibiotic therapy did not improve his symptoms following his diagnosis with pneumonia. A urinary antigen detection test was then conducted, leading to a diagnosis of LD. Despite the change of antibiotic to levofloxacin, multiple organ failure led to his death., Conclusion: Decontamination workers may be at a high risk for developing LD and living and working conditions among them are possible contributors.

Background: Legionella is a ubiquitous Gram-negative bacterium naturally found in aquatic environments. It can pose a health problem when it grows and spreads in man-made water systems. Legionella pneumophila is the most common cause of Legionnaires' disease nowadays, a community-acquired pneumonia with pulmonary symptoms and chest radiography no different from any other form of infectious pneumonia. Legionella monitoring is important for public health reasons, including the identification of unusual environmental sources of Legionella., Methods: We report two cases of Legionnaires' disease associated with two different car wash installations in the province of Vicenza, in the Veneto region, northeastern Italy. Patients were not employees of the car wash installations, but users of the service. In both cases, Legionella antigen was detected in urine using the Alere BinaxNOW® Legionella Urinary Antigen, and Legionella antibodies were detected in serum using SERION ELISA classic Legionella pneumophila 1-7 IgG and IgM. Water samples were also analyzed as part of the surveillance program for Legionella prevention and control in compliance with the Italian guidelines., Results: Both patients had clinical symptoms and chest radiography compatible with pneumonia, and only one of them had diabetes as a risk factor. Legionella urinary antigen and serological test on serum samples were positive for Legionella in both patients, even if much slighter in the case A due to the retrospective serological investigation performed a year later the episode and after the second clinical case occurred in the same district. The environmental investigations highlighted two different car wash plants as potential source of infection. A certified company using shock hyperchlorination was asked to disinfect the two plants and, subsequently, control samples resulted negative for Legionella pneumophila., Conclusion: Any water source producing aerosols should be considered at risk for the transmission of Legionella bacteria, including car wash installations frequently used by a large number of customers and where poor maintenance probably creates favorable conditions for Legionella overgrowth and spreading. Additional research is needed to ascertain optimal strategies for Legionella monitoring and control, but environmental surveillance, paying careful attention to possible unconventional sources, should remain an important component of any Legionnaires' disease prevention program. Additionally, all available diagnostic methods would be recommended for the confirmation of all cases even in the event of non-serogroup 1 Legionella pneumophila infection, probably underestimated at this time.

Objectives: Infections caused by Legionella are the leading cause of waterborne disease outbreaks in the United States. We investigated a large outbreak of Legionnaires' disease in New York City in summer 2015 to characterize patients, risk factors for mortality, and environmental exposures., Methods: We defined cases as patients with pneumonia and laboratory evidence of Legionella infection from July 2 through August 3, 2015, and with a history of residing in or visiting 1 of several South Bronx neighborhoods of New York City. We describe the epidemiologic, environmental, and laboratory investigation that identified the source of the outbreak., Results: We identified 138 patients with outbreak-related Legionnaires' disease, 16 of whom died. The median age of patients was 55. A total of 107 patients had a chronic health condition, including 43 with diabetes, 40 with alcoholism, and 24 with HIV infection. We tested 55 cooling towers for Legionella, and 2 had a strain indistinguishable by pulsed-field gel electrophoresis from 26 patient isolates. Whole-genome sequencing and epidemiologic evidence implicated 1 cooling tower as the source of the outbreak., Conclusions: A large outbreak of Legionnaires' disease caused by a cooling tower occurred in a medically vulnerable community. The outbreak prompted enactment of a new city law on the operation and maintenance of cooling towers. Ongoing surveillance and evaluation of cooling tower process controls will determine if the new law reduces the incidence of Legionnaires' disease in New York City.

Continuous environmental exposure of humans to Legionella may induce immune responses and generation of antibodies. The aim of this study was to investigate the seroprevalence of Legionella pneumophila serogroups (SG) 1-6 in the general healthy population and identify the associated host-related and environmental risk factors. L. pneumophila SG 1-6 seroprevalence among a total of 2007 blood samples collected from healthy donors was 4.8%. Seroprevalence was higher in women (5.9%) than men (3.3%) and in areas with a larger number of inhabitants, ranging from 3.5% in rural regions to 6.8% in the capital, Riga. Blood samples from inhabitants of apartment buildings tested positive for L. pneumophila in more cases (5.8%) compared to those from inhabitants of single-family homes (2.7%). Residents of buildings with a municipal hot water supply system were more likely to be seropositive for L. pneumophila (OR = 3.16, 95% CI 1.26-7.91). Previous episodes of fever were additionally identified as a risk factor (OR = 2.42, 95% CI 1.43-4.1). In conclusion, centralized hot water supply, female gender and previous episodes of fever were determined as the main factors associated with L. pneumophila seropositivity in our study population.

We herein report a fatal case of Legionella pneumophila pneumonia in a tocilizumab-treated rheumatoid arthritis patient who was in a state of shock on admission but remained afebrile even during severe pneumonia. Legionella antigen was detected in the urine and neutrophil CD64 expression was highly elevated. Despite undergoing intensive treatment, the patient developed sepsis and died 12 days after admission. An autopsy indicated that while the Legionella infection had almost been controlled, a subarachnoid hemorrhage was the ultimate cause of death.

Legionnaires' disease (LD) is an acute form of pneumonia, and changing weather is considered a plausible risk factor. Yet, the relationship between weather and LD has rarely been investigated, especially using long-term daily data. In this study, daily data was used to evaluate the impacts of precipitation, temperature, and relative humidity on LD occurrence in Taiwan from 1995-2011. A time-stratified 2:1 matched-period case-crossover design was used to compare each case with self-controlled data using a conditional logistic regression analysis, and odds ratios (ORs) for LD occurrence was estimated. The city, gender and age were defined as a stratum for each matched set to modify the effects. For lag day- 0 to 15, the precipitation at lag day-11 significantly affected LD occurrence (p<0.05), and a 2.5% (95% CIs = 0.3-4.7%) increased risk of LD occurrence was associated with every 5-mm increase in precipitation. In addition, stratified analyses further showed that positive associations of precipitation with LD incidence were only significant in male and elderly groups and during the warm season ORs = 1.023-1.029). However, such an effect was not completely linear. Only precipitations at 21-40 (OR = 1.643 (95% CIs = 1.074-2.513)) and 61-80 mm (OR = 2.572 (1.106-5.978)) significantly increased the risk of LD occurrence. Moreover, a negative correlation between mean temperature at an 11-day lag and LD occurrence was also found (OR = 0.975 (0.953-0.996)). No significant association between relative humidity and LD occurrence was identified (p>0.05). In conclusion, in warm, humid regions, an increase of daily precipitation is likely to be a critical weather factor triggering LD occurrence where the risk is found particularly significant at an 11-day lag. Additionally, precipitation at 21-40 and 61-80 mm might make LD occurrence more likely.

Objective: Our aim was to evaluate the impact of aerators on water microbiological contamination in at-risk hospital departments, with a view to quantifying the possible risk of patient exposure to waterborne microorganisms., Design: We analyzed the microbiological and chemical-physical characteristics of hot and cold water in some critical hospital departments., Setting: Two hospitals in northern Italy., Methods: We took 304 water samples over a 1-year period, at 3-month intervals, from taps used by healthcare personnel for handwashing, surgical washing, and the washing of medical equipment. We analyzed heterotrophic plate counts (HPCs) at 36°C and 22°C, nonfastidious gram-negative bacteria (GNB-NE), and Legionella pneumophila., Results: The percentages of positivity and mean values of HPCs at 22°C, HPCs at 36°C, and GNB-NE loads were significantly higher at outlet points than in the plumbing system. In particular, GNB-NE positivity was higher at outlet points than in the plumbing system in both the cold water (31.58% vs 6.58% of samples were positive) and hot water (21.05% vs 3.95%) supplies. Our results also revealed contamination by L. pneumophila both in the plumbing system and at outlet points, with percentages of positive samples varying according to the serogroup examined (serogroups 1 and 2-14). The mean concentrations displayed statistically significant (P < .001) differences between the outlet points (27,382.89 ± 42,245.33 colony-forming units [cfu]/L) and the plumbing system (19,461.84 ± 29,982.11 cfu/L)., Conclusions: These results reveal a high level of contamination of aerators by various species of gram-negative opportunists that are potentially very dangerous for immunocompromised patients and, therefore, the need to improve the management of these devices.

Objective: Community-acquired pneumonia (CAP) remains a major cause of death. No studies have reported the use of rapid influenza diagnostic tests (RIDT) for the etiological diagnosis, and the factors contributing to severity and mortality have not yet been fully investigated. The aim of this study was to review the etiologies of CAP using RIDT and to identify risk factors related to the severity and mortality of the disease., Methods: This retrospective study assessed these factors in hospitalized patients, with special emphasis on microbial etiology., Results: A total of 1,032 patients aged 63.9±18.3 years were studied, 66.2% of whom were men. Microbial identification was obtained in 57.0% of the cases. The most frequent causative microbial agents were Streptococcus pneumoniae, Mycoplasma pneumoniae and the influenza virus, and the second most frequent pathogens in the patients with severe CAP and the non-survivors were S. pneumoniae and the influenza virus. Age (≥65 years), chronic obstructive pulmonary disease, congestive heart failure, diabetes mellitus, dementia and Legionella spp. infection and polymicrobial infection were each found to be independent factors related to severity in the multivariate analysis, whereas "unidentified pathogen" was found to be an independent factor for non-severe CAP. Age (≥65 years), chronic pulmonary aspergillosis, post-lung cancer surgery and severe CAP were found to be independent factors for non-survival according to a multivariate analysis., Conclusion: In addition to S. pneumoniae, the influenza virus was a frequent cause of CAP overall and a frequent causative pathogen in both severe cases of CAP and non-survivors. Legionella spp. infection and polymicrobial infection were found to be an independent factor for the severity of CAP along with advanced age and certain comorbidities. An advanced age, certain respiratory comorbidities and severe CAP were found to be important independent factors for the mortality of CAP.

We report a fatal case of community-acquired Legionnaires' disease in an infant aged under six months. Epidemiological and microbiological investigations suggested that a free-standing cold water humidifier using domestic tap water contaminated with Legionella pneumophila serogroup 1 served as a vehicle for infection. These findings were corroborated by sequence-based typing (SBT). Humidifier-associated Legionnaires' disease can be prevented by appropriate control measures. This case also illustrates the emerging role of SBT in the investigation of legionellosis.

Background: The source of infection for most sporadic cases of Legionnaires' disease remains unknown. This study aims quantify the relationship between cases and wet cooling systems (WCS), a potential source of aerosolised legionella bacteria., Methods: The study analysed data on 1163 sporadic, community-acquired cases of Legionnaires' disease in England and Wales with onset between 1996 and 2006, and 11630 postcode controls randomly sampled in proportion to population size and matched on region, age group and sex. The relationship between risk of Legionnaires' disease and distance from a WCS was analysed by conditional logistic regression., Results: Cases and controls had a mean age of 56.3 years; 79.3% were male. Cases lived appreciably closer to WCS than their controls (mean distance of cases=2.11 km, controls=2.58 km; mean difference 0.47 km (95% CI 0.28 to 0.65)). The OR for disease within 1 km of a WCS compared with over 6 km (a distance taken to reflect background rates of Legionnaires' disease) was 1.59 (95% CI 1.26 to 2.01) when adjusted for socio-economic deprivation, and 1.33 (95% CI 1.04 to 1.71) when additionally adjusted for population density. The results suggest that residential proximity to a WCS may account for 19.6% of sporadic community-acquired cases., Conclusions: WCS may be an important source of sporadic, community-acquired cases of Legionnaires' disease, an observation that has important implications for health protection, especially given the likely increase in such systems as a component of strategies to improve energy efficiency in buildings.

Pulmonary infection after a tsunami is often polymicrobial and tends to form chronic pyogenic lung disease, necrotizing pneumonia, and empyemas. We report a combined pulmonary infection of Legionella and multiple antibiotic-resistant Escherichia coli in a previously well 75-year-old woman following immersion in tsunami waters 1 km inland from the Pacific coastline following the Tohoku Region Pacific Coast Earthquake of 2011. She needed drainage several times and the long-term use of multiple antibiotics according to the type of bacteria found and antibiotic susceptibility. We should be mindful of infections caused by multiple pathogens in the environment in Japan as a consequence of a tsunami disaster.

A source of infection is rarely identified for sporadic cases of Legionnaires' disease. We found that professional drivers are five times more commonly represented among community acquired sporadic cases in England and Wales than expected. We therefore investigated possible risk exposures in relation to driving or spending time in a motor vehicle. A case control study including all surviving community acquired sporadic cases in England and Wales with onset between 12 July 2008 and 9 March 2009 was carried out. Cases were contacted by phone and controls were consecutively recruited by sequential digital dialling matched by area code, sex and age group. Those who consented were sent a questionnaire asking questions on driving habits, potential sources in vehicles and known risk factors. The results were analysed using logistic regression. 75 cases and 67 controls were included in the study. Multivariable analysis identified two exposures linked to vehicle use associated with an increased risk of Legionnaires' disease: Driving through industrial areas (OR 7.2, 95%CI 1.5-33.7) and driving or being a passenger in a vehicle with windscreen wiper fluid not containing added screenwash (OR 47.2, 95%CI 3.7-603.6). Not adding screenwash to windscreen wiper fluid is a previously unidentified risk factor and appears to be strongly associated with community acquired sporadic cases of Legionnaires' disease. We estimated that around 20% of community acquired sporadic cases could be attributed to this exposure. A simple recommendation to use screenwash may mitigate transmission of Legionella bacteria to drivers and passengers.

In June and July 2008, two office workers were admitted to a Dublin hospital with Legionnaires' disease. Investigations showed that cooling towers in the basement car park were the most likely source of infection. However, positive results from cooling tower samples by polymerase chain reaction (PCR) did not correlate with subsequent culture results. Also, many employees reported Pontiac fever-like morbidity following notification of the second case of Legionnaires' disease. In total, 54 employees attended their general practitioner or emergency department with symptoms of Legionnaires' disease or Pontiac fever. However, all laboratory tests for Legionnaires' disease or Pontiac fever were negative. In this investigation, email was used extensively for active case finding and provision of time information to employees and medical colleagues. We recommend clarification of the role of PCR in the diagnosis of legionellosis and also advocate for a specific laboratory test for the diagnosis of the milder form of legionellosis as in Pontiac fever.

Two cases of fulminant pulmonary legionellosis, complicated by prolonged intensive care unit stays and acute respiratory distress syndrome, and who were recently treated with infliximab for Crohn's disease, are described. A review of the literature revealed three additional cases in patients with inflammatory bowel disease, and a total of 22 cases of Legionella pneumophila pneumonia in the context of treatment with antitumour necrosis (TNF)-alpha medications. The median age of the patients was 49 years, and men and women were affected equally. The case fatality rate was 14% (three of 22). Early recognition and treatment of this anti-TNF-alpha-related complication would likely result in reduced mortality and morbidity. Physicians prescribing anti-TNF-alpha drugs should be aware of this association.

Legionnaires' disease (LD) is a major cause of severe community-acquired pneumonia but the source and mode of transmission are not always apparent, especially in sporadic cases. We hypothesized that LD can be acquired from the air-conditioning systems of motor cars. Swabs were taken from the evaporator compartments of the air-conditioning system of scrapped cars. Healthy subjects who were mainly employees of regional transportation companies were tested for antibody to Legionella pneumophila serogroups 1-6; they also completed a questionnaire. Legionella species were detected in 11/22 scrapped cars by the loop-mediated isothermal amplification method. The prevalence of microplate agglutination titres > or =1:32 was significantly higher in subjects who sometimes used car air-conditioning systems. Although we did not prove a direct link between Legionella spp. in the car evaporator and LD, our findings point to a potential risk of car air-conditioning systems in LD, which needs further investigation.

In May 2008, a report of two workers from the same construction equipment manufacturing plant who were admitted to hospital with Legionnaires disease confirmed by urine antigen prompted an outbreak investigation. Both cases were middle aged men, smokers, and with no travel, leisure or other common community exposure to Legionella sources. There were no wet cooling towers at the plant or in the surrounding area. No increase in respiratory disease or worker absenteeism occurred at the plant during the preceding month. Wider case ascertainment including alerts to hospitals and medical practitioners yielded no further cases. The environmental investigation (and sampling of water systems for Legionella) identified a Legionella pneumophila serogroup1 (Mab 2b) count of >3.0x10(4)cfu/l in water samples from an aqueous metal pre-treatment tunnel, which generates profuse water aerosol. Drainage, cleaning and biocide treatment using thiazalone eliminated Legionella from the system.

Legionella spp. are pathogens that can cause Legionnaires' disease in humans through inhalation of contaminated aerosols. The principal reservoir for these microorganisms is water, but Legionella spp. have been isolated from composted vegetable and plant material, and from many potting mixes as well. In Australia, there have been several cases of Legionnaires' disease in which Legionella longbeachae has been isolated from potting soils. In Switzerland, the source of infection cannot always be identified as water or cooling towers: therefore, we have investigated 46 commercially available potting soils in Switzerland to determine the presence of Legionella spp. We were able to detect Legionella spp. in 45.7% (21/46) of the potting soil samples analysed by culture. Legionella pneumophila was present in 19.6% (9/46) of the samples and L. pneumophila serogroup 1 in 6.5% (3/46). Quantification by both culture and quantitative real-time PCR revealed high concentrations of legionellae in potting soils, ranging between 10(3) CFU/g and 10(5) CFU/g and 10(4) genomic units (GU)/g and 10(6) GU/g, respectively. Thus, potting soils may represent an alternative reservoir for Legionella spp. in Switzerland.

Legionella species are increasingly recognized as a cause of both healthcare- and community-acquired pneumonia (so-called "Legionnaire's disease"). These pathogens are ubiquitous in the environment, but environmental factors in the occurrence of sporadic legionellosis remain poorly understood. We analyzed all legionellosis cases identified in the Greater Toronto Area of Ontario from 1978 to 2006, and evaluated seasonal and environmental patterns in legionellosis case occurrence by using both negative binomial models and case-crossover analysis. A total of 837 cases were reported during the study period. After adjusting for seasonal effects, changes in the local watershed, rather than weather, were the strongest contributors to legionellosis risk. A 3.6-fold increase (95% confidence interval (CI), 2.4-5.3) in odds of disease was identified with decreasing watershed levels approximately 4 weeks before case-occurrence. We also found a 33% increase (95% CI, 8-64%) in odds of disease with decreasing lake temperature during the same period and a 34% increase (95% CI, 14-57%) with increasing humidity 5 weeks before case-occurrence. We conclude that local watershed ecology influences the risk of legionellosis, notwithstanding the availability of advanced water treatment capacity in Toronto. Enhancement of risk might occur through direct contamination of water sources or via introduction of micronutrients or commensal organisms into residential and hospital water supplies. These observations suggest testable hypotheses for future empiric studies.

A fatal nosocomial infection with Legionella pneumophila serogroup 5 occurred in a patient with leukemia. Isolates recovered from both the potable water supply and the patient showed an identical genomic profile. With no other exposure identified, the water from the washbasin was evidently the source of infection.

Problem/condition: Since 1971, CDC, the U.S. Environmental Protection Agency (EPA), and the Council of State and Territorial Epidemiologists have maintained a collaborative Waterborne Disease and Outbreak Surveillance System (WBDOSS) for collecting and reporting data related to occurrences and causes of waterborne-disease outbreaks (WBDOs) and cases of waterborne disease. This surveillance system is the primary source of data concerning the scope and effects of waterborne disease in the United States., Reporting Period: Data presented summarize 28 WBDOs that occurred during January 2005--December 2006 and four previously unreported WBDOs that occurred during 1979--2002., Description of System: The surveillance system includes data on WBDOs associated with recreational water, drinking water, water not intended for drinking (WNID) (excluding recreational water), and water use of unknown intent. Public health departments in the states, territories, localities, and Freely Associated States (FAS) (i.e., the Republic of the Marshall Islands, the Federated States of Micronesia, and the Republic of Palau, formerly parts of the U.S.-administered Trust Territory of the Pacific Islands) are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC by a standard form. Only cases and outbreaks associated with drinking water, WNID (excluding recreational water), and water of unknown intent (WUI) are summarized in this report. Cases and outbreaks associated with recreational water are reported in a separate Surveillance Summary., Results: Fourteen states reported 28 WBDOs that occurred during 2005--2006: a total of 20 were associated with drinking water, six were associated with WNID, and two were associated with WUI. The 20 drinking water-associated WBDOs caused illness among an estimated 612 persons and were linked to four deaths. Etiologic agents were identified in 18 (90.0%) of the drinking water-associated WBDOs. Among the 18 WBDOs with identified pathogens, 12 (66.7%) were associated with bacteria, three (16.7%) with viruses, two (11.1%) with parasites, and one (5.6%) mixed WBDO with both bacteria and viruses. In both WBDOs where the etiology was not determined, norovirus was the suspected etiology. Of the 20 drinking water WBDOs, 10 (50) were outbreaks of acute respiratory illness (ARI), nine (45%) were outbreaks of acute gastrointestinal illness (AGI), and one (5.0%) was an outbreak of hepatitis. All WBDOs of ARI were caused by Legionella, and this is the first reporting period in which the proportion of ARI WBDOs has surpassed that of AGI WBDOs since the reporting of Legionella WBDOs was initiated in 2001. A total of 23 deficiencies were cited in the 20 WBDOs associated with drinking water: 12 (52.2%) deficiencies fell under the classification NWU/POU (deficiencies occurred at points not under the jurisdiction of a water utility or at the point-of-use), 10 (43.5%) deficiencies fell under the classification SWTDs (contamination at or in the source water, treatment facility, or distribution system), and for one (4.3%) deficiency, classification was unknown. Among the 12 NWU/POU deficiencies, 10 (83.3%) involved Legionella spp. in the drinking water system. The most frequently cited SWTD deficiencies were associated with a treatment deficiency (n = four [40.0%]) and untreated ground water (n = four [40.0%]). Three of the four WBDOs with treatment deficiencies used ground water sources., Interpretation: Approximately half (52.2%) of the drinking water deficiencies occurred outside the jurisdiction of a water utility. The majority of these WBDOs were associated with Legionella spp, which suggests that increased attention should be targeted towards reducing illness risks associated with Legionella spp. Nearly all of WBDOs associated with SWTD deficiencies occurred in systems using ground water. EPA's new Ground Water Rule might prevent similar outbreaks in the future in public water systems., Public Health Actions: CDC and EPA use surveillance data to identify the types of water systems, deficiencies, and etiologic agents associated with WBDOs and to evaluate the adequacy of current technologies and practices for providing safe drinking water. Surveillance data also are used to establish research priorities, which can lead to improved water-quality regulation development. The majority of drinking water deficiencies are now associated with contamination at points outside the jurisdiction of public water systems (e.g., regrowth of Legionella spp. in hot water systems) and water contamination that might not be regulated by EPA (e.g., contamination of tap water at the POU). Improved education of consumers and plumbers might help address these risk factors.

To estimate incidence and completeness of notification of Legionnaires' disease (LD) in The Netherlands in 2000 and 2001, we performed a capture-recapture analysis using three registers: Notifications, Laboratory results and Hospital admissions. After record-linkage, 373 of the 780 LD patients identified were notified. Ascertained under-notification was 52.2%. Because of expected and observed regional differences in the incidence rate of LD, alternatively to conventional log-linear capture-recapture models, a covariate (region) capture-recapture model, not previously used for estimating infectious disease incidence, was specified and estimated 886 LD patients (95% confidence interval 827-1022). Estimated under-notification was 57.9%. Notified, ascertained and estimated average annual incidence rates of LD were 1.15, 2.42 and 2.77/100 000 inhabitants respectively, with the highest incidence in the southern region of The Netherlands. Covariate capture-recapture analysis acknowledging regional differences of LD incidence appears to reduce bias in the estimated national incidence rate.

Background: Cases of legionellosis sometimes arise in the form of aggregations which are difficult to interpret. This study provides an analysis of these groupings having arisen one summer in Castellon., Methods: Microbiological, clinical and epidemiological field methods were employed., Results: Within a few days, there were five (5) cases of legionella pneumonia in workers related to various ceramic industries within an area where a large number of these plants are located. Two constituted a minor outbreak. By means of molecular biology techniques performed on the strains, the common origins of three of the cases were ruled out., Conclusions: It is debated whether this episode of an outbreak having arisen within the context of a broader-ranging cluster of cases of a multi-focal origin was a chance event or whether it was the manifestation of a risk related to this industrial activity which might repeat itself.

A prospective surveillance study of legionnaires disease and an environmental survey of Legionella species were performed simultaneously in a general hospital. During a period of 3 years, 705 patients with pneumonia were screened with a Legionella urinary antigen test, and pneumonia was confirmed by culture and serological tests. Twelve cases of legionnaires disease were identified, none of which were hospital acquired, despite the fact that 60% of hospital water samples were contaminated with Legionella pneumophila at a concentration of more than 10(3) colony-forming units/L. The probable source of infection was identified for only 2 community-acquired cases. The results show that environmental contamination alone is not able to predict the risk of legionnaires disease. If no cases are present, monitoring of hospital water systems is of little significance; clinical surveillance is much more important.

Legionella pneumophila causes community- and hospital-acquired pneumonia. Lung airway and alveolar epithelial cells comprise an important barrier against airborne pathogens. Cyclooxygenase (COX) and microsomal PGE(2) synthase-1 (mPGES-1)-derived prostaglandins like prostaglandin E(2) (PGE(2)) are considered as important regulators of lung function. Herein we tested the hypothesis that L. pneumophila induced COX-2 and mPGES-1-dependent PGE(2) production in pulmonary epithelial cells. Legionella induced the release of PGE(2) in primary human small airway epithelial cells and A549 cells. This was accompanied by an increased expression of COX-2 and mPGES-1 as well as an increased PLA(2) activity in infected cells. Deletion of the type IV secretion system Dot/Icm did not impair Legionella-related COX-2 expression or PGE(2) release in A549 cells. L. pneumophila induced the degradation of IkappaBalpha and activated NF-kappaB. Inhibition of IKK blocked L. pneumophila-induced PGE(2) release and COX-2 expression. We noted activation of p38 and p42/44 MAP kinase in Legionella-infected A549 cells. Moreover, membrane translocation and activation of PKCalpha was observed in infected cells. PKCalpha and p38 and p42/44 MAP kinase inhibitors reduced PGE(2) release and COX-2 expression. In summary, PKCalpha and p38 and p42/44 MAP kinase controlled COX-2 expression and subsequent PGE(2) release by Legionella-infected lung epithelial cells. These pathways may significantly contribute to the host response in Legionnaires' disease.

In January 2003, two cases of Legionnaires' disease associated with a ship's cruise were registered in the database of National Epidemiological Surveillance of Infectious Diseases. A 70-year-old male heavy smoker with mild emphysema contracted the disease during a cruise. Legionella pneumophila serogroup (sg) 5 was isolated from the patient's sputum and the ship's indoor spa. The isolate from the spa matched the patient's isolate by genotyping performed by pulsed-field gel electrophoresis (PFGE). The second case was in a 73-year-old female. During epidemiological investigation, a third case of Legionnaire's disease in a 71-year-old male was subsequently diagnosed among passengers on the same ship on the following cruise. Environmental investigation revealed that porous natural stones (Maifanshi) in the filters of the spas had harboured L. pneumophila, a phenomenon which has not been reported except in Japan. This is the first documented evidence of L. pneumophila sg 5 infection on a ship and of porous stones as a source of Legionella infection.

Objective: To investigate the potential source of a case of Legionnaires' disease caused by an unusual serotype of Legionella pneumophila serogroup 1 (Lp1) in regional Victoria in May 2001., Method: Epidemiological and environmental investigation of the source of infection of a case of Legionnaires' disease in regional Victoria in May 2001., Results: Extensive environmental investigations did not reveal any cooling water tower systems close to the residence or the shopping centre that the case visited prior to illness. The sputum culture and a soil sample from the field at the plant nursery where the case worked prior to illness were both positive for Legionella pneumophilia serogroup 1, MDU pulsovar 97:103., Conclusion: Legionella pneumophila has been found in soil and was further found to be associated with a case of Legionella pneumophila., Implications: Public health authorities should consider exposures to soil and potting mixes when investigating cases of Legionella pneumophila where the case has no apparent association with cooling towers. Safe gardening practices should be promoted among the community.

Legionella pneumophila is an important cause of community-acquired pneumonia. Domestic sources of infection have been increasingly recognised among community-acquired cases. This report summarises the public health investigations and management of a single community-acquired case of Legionnaires' disease in Queensland, commenced in the context of a suspected outbreak. Legionellae from the case's domestic water supply were indistinguishable from the clinical isolate. The implications for future investigation of sporadic cases are discussed.

During October 2003-February 2004, eight cases (seven confirmed cases and one possible) of Legionnaires disease (LD) were identified among guests at a hotel in Ocean City, Maryland. This report summarizes the subsequent investigation conducted by the Worcester County Health Department (WCHD), Maryland Department of Health and Mental Hygiene (DHMH), and CDC, which implicated the potable hot water system of the hotel as the most likely source of infection. The detection of this outbreak underscores the importance of enhanced, state-based surveillance for timely detection of travel-associated LD and implementation of control measures.

We investigated Legionella and Pseudomonas contamination of hot water in a cross-sectional multicentric survey in Italy. Chemical parameters (hardness, free chlorine, and trace elements) were determined. Legionella spp. were detected in 33 (22.6%) and Pseudomonas spp. in 56 (38.4%) of 146 samples. Some factors associated with Legionella contamination were heater type, tank distance and capacity, water plant age, and mineral content. Pseudomonas presence was influenced by water source, hardness, free chlorine, and temperature. Legionella contamination was associated with a centralized heater, distance from the heater point >10 m, and a water plant >10 years old. Furthermore, zinc levels of <100 microg/L and copper levels of >50 microg/L appeared to be protective against Legionella colonization [corrected]. Legionella species and serogroups were differently distributed according to heater type, water temperature, and free chlorine, suggesting that Legionella strains may have a different sensibility and resistance to environmental factors and different ecologic niches.

Legionella pneumophila has become a paradigm for facultative intracellular pathogens that modulate biogenesis of their phagosomes into replicative niches. The ability to alter host cell biology and tailor it into a hospitable host for intracellular proliferation is at the crux of the mechanism of pathogenesis of Legionnaires' disease.

Objective: To study the epidemiologic manifestations of a large outbreak of Legionnaires' disease due to an inadequate circulating and filtration system for bath water., Patients: In June 2000 at Ishioka City, Ibaraki Prefecture, a large outbreak of Legionnaire's disease occurred, as a result of an inadequate circulating and filtration system for communal bath water. This outbreak was the worst ever experienced in Japan, involving a total of 34 patients (20 confirmed, 14 probable), 3 of whom died., Measurements and Results: Legionella pneumophila serogroup 1 was isolated from sputum culture in two patients. Bacteriological culture of the public bath water subsequently yielded large numbers of Legionella species. Cleavage of genomic DNA showed that restriction fragment patterns coming from clinical and environmental isolates of L. pneumophila serogroup 1 were closely related, focusing the inquiry to a public bathhouse where a circulating filtration system was suspected as the source of infection., Conclusions: It was later concluded that the circulating filtration system adopted for bath water was marred by a serious design flaw that subsequently caused the mass outbreak. Specifically, a line of the bath water was being returned to the bath without undergoing heat exchange or sterilization by chlorine; and the Legionella species that had proliferated in the filter and the bright stone filtration unit were allowed to return to the bath, eventually culminating in a mass infection.

The virulence factor Mip (macrophage infectivity potentiator) contributes to the intracellular survival of Legionella pneumophila, the causative agent of Legionnaires' disease. The protein consists of two domains that are connected via a very long alpha-helix (A. Riboldi-Tunnicliffe et al., Nat. Struct. Biol. 8:779-783, 2001). The fold of the C-terminal domain (residues 100 to 213) is closely related to human FK506-binding protein (FKBP12), and like FKBP12, Mip exhibits peptidylprolyl cis/trans isomerase (PPIase) activity. The alpha-helical N-terminal domain is responsible for the formation of very stable Mip homodimers. In order to determine the importance of the homodimeric state of Mip for its biochemical activities and for infectivity of Legionella, a truncated, monomeric Mip variant [Mip((77-213))] was overexpressed in Escherichia coli and characterized biochemically. In vitro isomerase activity assays revealed that the altered protein exhibits full isomerase activity towards peptide substrates. However, the deletion resulted in a dramatic loss in the efficiency of refolding of reduced and carboxy-methylated RNase T(1). By cis complementation of the Mip-negative mutant strain L. pneumophila JR32-2, we constructed the strain L. pneumophila JR32-2.4, which expresses an N-terminally truncated variant of Mip. Infection studies with these strains revealed that the N-terminal part and the dimerization of Mip but not its PPIase activity are necessary for full virulence in Acanthamoeba castellanii. Infection of guinea pigs showed that strains with dimerization-deficient Mip (JR32-2.4) or a very low PPIase activity (JR32-2.2) were significantly attenuated in the animal model. These results suggest a different role of the PPIase activity and the N-terminally mediated dimeric state of Mip in monocellular systems and during the infection of guinea pigs.

Background and Objectives: Hospital-acquired legionnaires' disease can be prevented by disinfection of hospital water systems. This study assessed the long-term efficacy of copper-silver ionization as a disinfection method in controlling Legionella in hospital water systems and reducing the incidence of hospital-acquired legionnaires' disease. A standardized, evidence-based approach to assist hospitals with decision making concerning the possible purchase of a disinfection system is presented., Design: The first 16 hospitals to install copper-silver ionization systems for Legionella disinfection were surveyed. Surveys conducted in 1995 and 2000 documented the experiences of the hospitals with maintenance of the system, contamination of water with Legionella, and occurrence of hospital-acquired legionnaires' disease. All were acute care hospitals with a mean of 435 beds., Results: All 16 hospitals reported cases of hospital-acquired legionnaires' disease prior to installing the copper-silver ionization system. Seventy-five percent had previously attempted other disinfection methods including superheat and flush, ultraviolet light, and hyperchlorination. By 2000, the ionization systems had been operational from 5 to 11 years. Prior to installation, 47% of the hospitals reported that more than 30% of distal water sites yielded Legionella. In 1995, after installation, 50% of the hospitals reported 0% positivity, and 43% still reported 0% in 2000. Moreover, no cases of hospital-acquired legionnaires' disease have occurred in any hospital since 1995., Conclusions: This study represents the final step in a proposed 4-step evaluation process of disinfection systems that includes (1) demonstrated efficacy of Legionella eradication in vitro using laboratory assays, (2) anecdotal experiences in preventing legionnaires' disease in individual hospitals, (3) controlled studies in individual hospitals, and (4) validation in confirmatory reports from multiple hospitals during a prolonged time (5 to 11 years in this study). Copper-silver ionization is now the only disinfection modality to have fulfilled all four evaluation criteria.