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We used US population-based surveillance data to characterize clinical risk factors for Legionnaires' disease (LD). The LD incidence increased by age and the risk was elevated for 12 clinical conditions, when compared to healthy adults. This information can be used to guide testing, treatment, and public health prevention efforts., (Published by Oxford University Press for the Infectious Diseases Society of America 2019.)

Background: Legionnaires' disease is an important cause of hospital-acquired pneumonia and is caused by infection with the bacterium Legionella. Because current typing methods often fail to resolve the infection source in possible nosocomial cases, we aimed to determine whether whole-genome sequencing (WGS) could be used to support or refute suspected links between cases and hospitals. We focused on cases involving a major nosocomial-associated strain, L. pneumophila sequence type (ST) 1., Methods: WGS data from 229 L. pneumophila ST1 isolates were analyzed, including 99 isolates from the water systems of 17 hospitals and 42 clinical isolates from patients with confirmed or suspected hospital-acquired infections, as well as isolates obtained from or associated with community-acquired sources of Legionnaires' disease., Results: Phylogenetic analysis demonstrated that all hospitals from which multiple isolates were obtained have been colonized by 1 or more distinct ST1 populations. However, deep sampling of 1 hospital also revealed the existence of substantial diversity and ward-specific microevolution within the population. Across all hospitals, suspected links with cases were supported with WGS, although the degree of support was dependent on the depth of environmental sampling and available contextual information. Finally, phylogeographic analysis revealed that hospitals have been seeded with L. pneumophila via both local and international spread of ST1., Conclusions: WGS can be used to support or refute suspected links between hospitals and Legionnaires' disease cases. However, deep hospital sampling is frequently required due to the potential coexistence of multiple populations, existence of substantial diversity, and similarity of hospital isolates to local populations., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.)

Background: Two proven nosocomial cases of Legionella pneumonia occurred at the Wesley Hospital (Brisbane, Australia) in May 2013. To trace the epidemiology of these cases, whole genome sequence analysis was performed on Legionella pneumophila isolates from the infected patients, prospective isolates collected from the hospital water distribution system (WDS), and retrospective patient isolates available from the Wesley Hospital and other local hospitals., Methods: Legionella pneumophila serogroup 1 isolates were cultured from patient sputum (n = 3), endobronchial washings (n = 3), pleural fluid (n = 1), and the Wesley Hospital WDS (n = 39). Whole genome sequencing and de novo assembly allowed comparison with the L. pneumophila Paris reference strain to infer phylogenetic and epidemiological relationships. Rapid disinfection of the hospital WDS with a chlorinated, alkaline detergent and subsequent superchlorination followed by maintenance of residual free chlorine, combined with removal of redundant plumbing, was instituted., Results: The 2011 and 2013 L. pneumophila patient isolates were serogroup 1 and closely related to all 2013 hospital water isolates based on single nucleotide polymorphisms and mobile genetic element profiles, suggesting a single L. pneumophila population as the source of nosocomial infection. The L. pneumophila population has evolved to comprise 3 clonal variants, each associated with different parts of the hospital WDS., Conclusions: This study provides an exemplar for the use of clinical and genomic epidemiological methods together with a program of rapid, effective remedial biofilm, plumbing and water treatment to characterize and eliminate a L. pneumophila population responsible for nosocomial infections., (© The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)

Background: Healthcare-associated Legionnaires' disease (LD) is a preventable pneumonia with a 30% case fatality rate. The Centers for Disease Control and Prevention guidelines recommend a high index of suspicion for the diagnosis of healthcare-associated LD. We characterized an outbreak and evaluated contributing factors in a hospital using copper-silver ionization for prevention of Legionella growth in water., Methods: Through medical records review at a large, urban tertiary care hospital in November 2012, we identified patients diagnosed with LD during 2011-2012. Laboratory-confirmed cases were categorized as definite, probable, and not healthcare associated based on time spent in the hospital during the incubation period. We performed an environmental assessment of the hospital, including collection of samples for Legionella culture. Clinical and environmental isolates were compared by genotyping. Copper and silver ion concentrations were measured in 11 water samples., Results: We identified 5 definite and 17 probable healthcare-associated LD cases; 6 case patients died. Of 25 locations (mostly potable water) where environmental samples were obtained for Legionella-specific culture, all but 2 showed Legionella growth; 11 isolates were identical to 3 clinical isolates by sequence-based typing. Mean copper and silver concentrations were at or above the manufacturer's recommended target for Legionella control. Despite this, all samples where copper and silver concentrations were tested showed Legionella growth., Conclusions: This outbreak was linked to the hospital's potable water system and highlights the importance of maintaining a high index of suspicion for healthcare-associated LD, even in the setting of a long-term disinfection program., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Background: To date, all descriptions of legionellosis in neonates have emerged from a small number of isolated case reports in newborns with unusually severe pneumonia. In December 2008, a large outbreak of Legionella infection occurred in term neonates in Cyprus, providing new information on the epidemiological and clinical features of Legionellosis in this age group., Methods: An environmental investigation was performed at a small private hospital where the infected neonates were delivered. The medical records of the infected neonates were retrospectively reviewed to obtain clinical data on presentation, complications, and course of disease., Results: Nine of the 32 (28%) newborns who were exposed to the contaminated source at the private nursery were infected with Legionella. Six subjects had pulmonary infiltrates, but in 3 cases there were no abnormal radiological findings and clinical presentation was mild. In 4 neonates, pulmonary infiltrates at presentation were bilateral and extensive and 3 died, conferring a mortality rate of 50% in subjects with pulmonary infiltrates and an overall mortality of 33.3%. Legionella pneumophila serogroup 3 was recovered in neonatal biological samples, although in some patients there was implication of a second strain, serogroup 1. It was determined that the neonates were infected while in the nursery at the private hospital by aerosol produced by a recently installed cold-mist humidifier that was filled with contaminated water., Conclusions: Use of humidifiers in nursery units must be avoided as the risk of disseminating Legionella in neonates is very high. In neonates legionellosis should be suspected when signs of infection first appear and take an unusual course, even when no pulmonary infiltrates appear.

Background: In France, Legionnaires disease is mainly caused by Legionella pneumophila. Here, we investigated possible host factors associated with susceptibility to community-acquired Legionnaires disease caused by the endemic Paris and Lorraine strains., Methods: We conducted a double-nested exploratory case-control study with use of data from the French national surveillance network of incident Legionnaires disease cases notified from 1998 through 2007. Patients with community-acquired Legionnaires disease and an L. pneumophila serogroup 1 isolate were eligible. Case patients were patients infected by the Paris or Lorraine strain, and control patients were those infected by sporadic strains. Epidemiological and clinical factors associated with infection with the Paris and Lorraine strains were assessed by calculating adjusted odds ratios (aOR) in multivariate logistic regression models., Results: We studied 1090 patients infected by sporadic strains (n = 920), the Paris strain (n = 80), or the Lorraine strain (n = 90). Infection with the Paris strain was significantly associated with female sex (aOR, 1.98; 95% confidence interval [CI], 1.19-3.28), steroid therapy (aOR, 3.16; 95% CI, 1.76-5.68), and a history of cancer or hematologic malignancies (aOR, 2.08; 95% CI, 1.15-3.76). In addition, the mortality rate was higher among patients infected with the Paris strain than in the control group (38% vs. 25.5%). The Lorraine strain was associated with smoking (aOR, 1.82; 95% CI, 1.14-2.91) and reduced mortality (9.9%). ., Conclusion: Several host characteristics were associated with the risk of infection by endemic strains of L. pneumophila serogroup 1. These findings may help to guide preventive measures. Factors predisposing patients to infection by specific strains need to be explored further.

The Pittsburgh Veterans Affairs hospital administration closed the research laboratory directed by Victor Yu and Janet Stout and destroyed isolates collected as part of a series of clinical studies over 25 years. This article discusses the implications and protests such destruction as an affront to science and scientific study. A petition signed by 243 individuals accompanies this article.

Background: On 21 May 2005, the Norwegian health authorities were alerted by officials from a local hospital that several recent patients had received the diagnosis of legionnaires disease; all patients resided in 2 neighboring municipalities. We investigated the outbreak to identify the source and to implement control measures., Methods: We interviewed all surviving case patients and investigated and harvested samples from 23 businesses with cooling towers and other potential infection sources. The locations of the businesses and the patients' residences and movements were mapped. We calculated attack rates and risk ratios among people living within various radii of each potential source. Isolates of Legionella pneumophila were compared using molecular methods., Results: Among 56 case patients, 10 died. The case patients became ill 12-25 May, resided up to 20 km apart, and had not visited places in common. Those living up to 1 km from a particular air scrubber had the highest risk ratio, and only for this source did the risk ratio decrease as the radius widened. Genetically identical L. pneumophila serogroup 1 isolates were recovered from patients and the air scrubber. The air scrubber is an industrial pollution-control device that cleans air for dust particles by spraying with water. The circulating water had a high organic content, pH of 8-9, and temperature of 40 degrees C. The air was expelled at 20 m/s and contained a high amount of aerosolized water., Conclusions: The high velocity, large drift, and high humidity in the air scrubber may have contributed to the wide spread of Legionella species, probably for >10 km. The risk of Legionella spread from air scrubbers should be assessed.

We evaluated the impact of the copper-silver ionization system in a hospital where hyperendemic nosocomial legionellosis and was present and all previous disinfection measures had failed. After implementation of the copper-silver ionization system, environmental colonization with Legionella species decreased significantly, and the incidence of nosocomial legionellosis decreased dramatically, from 2.45 to 0.18 cases per 1000 patient discharges.

Background: During March 2004, a large outbreak of legionnaires disease and Pontiac fever occurred among hotel guests in Oklahoma. An investigation was conducted to identify the source and evaluate the utility of the Legionella urine antigen assay and serologic testing for the identification of Pontiac fever., Methods: A retrospective cohort investigation of hotel guests and employees and an environmental evaluation were performed. Participants were interviewed, and clinical specimens were collected from consenting individuals., Results: Six cases of legionnaires disease and 101 cases of Pontiac fever were identified. Exposure to the indoor pool and hot tub area was associated with legionellosis (relative risk, 4.4; 95% confidence interval, 2.8-6.9). Specimens from the pool and hot tub tested positive for Legionella pneumophila serogroup 1 by polymerase chain reaction. For Pontiac fever, the sensitivity and positive predictive value were 35.7% and 100%, respectively, for the urine antigen assay, and 46.4% and 90%, respectively, for serologic testing. The specificity and negative predictive value were 100% and 47.8%, respectively, for the urine antigen assay, and 89.3% and 45.5%, respectively, for serologic testing., Conclusions: Urine antigen testing, with or without serologic testing, can be used to confirm outbreak-associated cases of Pontiac fever caused by L. pneumophila serogroup 1.

We investigated 3 cases of legionnaires disease (LD) that developed in travelers who stayed at a hotel in the United States Virgin Islands where cases of LD occurred in 1981-1982 and in 1998. The temperature of the potable water at the hotel was in a range that could optimally support the growth of Legionella species, and the potable water was colonized with Legionella pneumophila in 1981-1982 and in 2002-2003.

This case-control study investigated a cluster of respiratory illness among patrons of a restaurant. Of 173 patrons interviewed, 117 (68%) were ill. Symptoms included myalgias (93%), headache (87%), and fatigue (79%). The mean incubation period was 49 h and the mean duration of illness was 71 h. Patrons aged >15 years were more likely to have been ill than younger patrons (odds ratio [OR], 2.96; P=.002); 58% of persons who were ill sat near a large fountain, compared with 18% of respondents who were not ill (OR, 7.5; P=.005). Legionella anisa was cultured from water samples obtained from the fountain pool. Of 22 individuals who were ill, 11 (50%) had a > or =4-fold increase in the titer of antibody to that strain of L. anisa from acute-phase to convalescent-phase serum samples; 3 others (14%) had persistently elevated titers of > or =512; of a group of 20 individuals who had not been exposed to the restaurant, none had titers of >128. Pontiac fever should be considered as a diagnosis during acute outbreaks of influenza-like illness with a high attack rate and no other identified etiology.

Legionella pneumophila serogroup 6 was recovered from a bronchoalveolar lavage specimen from a 1-week-old, full-term newborn with pneumonia, as well as from water samples from the maternity hospital and the newborn's home (an apartment). Amplified fragment-length polymorphism typing revealed that the strains isolated from the newborn and her home were indistinguishable from each other but were clearly different from the hospital and control strains. To our knowledge, this is the first report of domestic acquisition of legionnaires disease in a newborn to have been confirmed by molecular typing.

A follow-up study of 122 survivors of an outbreak of legionnaires disease (LD) in The Netherlands was conducted to determine persistence of symptoms, health-related quality of life (HRQL), and presence of posttraumatic stress disorder (PTSD). Seventeen months after diagnosis of LD, survivors completed a questionnaire assessing symptoms and HRQL and a questionnaire assessing PTSD. The most prevalent new symptoms were fatigue (in 75% of patients), neurologic symptoms (in 66%), and neuromuscular symptoms (in 63%). HRQL was impaired in 7 of the 8 dimensions assessed by the HRQL questionnaire, and 15% of patients experienced PTSD. Symptoms and impaired HRQL persisted for >1.5 years. As a result of the design of this study, it could not be inferred whether Legionella pneumophila infection, severe pneumonia in general, or the outbreak situation was responsible for impaired well-being. However, awareness of this problem by health care providers may improve the aftercare of patients.

Internet resources that focus on Legionella and legionnaires disease are presented. Web sites were selected on the basis of their content and adherence to suggested standards of medical Internet publishing. Free, accessible, English-language Web sites were categorized according to users' needs as follows: (1) those with comprehensive information on Legionella infection (including pathophysiologic characteristics, symptoms, and treatment of legionnaires disease), (2) those with information on outbreaks and epidemiology (including information for travelers), (3) those with information for researchers, (4) those about prevention, and (5) those with information for laypersons.

The occurrence of legionnaires' disease has been described previously in passengers of cruise ships, but determination of the source has been rare. A 67-year-old, male cigarette smoker with heart disease contracted legionnaires' disease during a cruise in September 1995 and died 9 days after disembarking. Legionella pneumophila serogroup 1 was isolated from the patient's sputum and the ship's water supply. Samples from the air-conditioning system were negative. L. pneumophila serogroup 1 isolates from the water supply matched the patient's isolate, by both monoclonal antibody subtyping and genomic fingerprinting. None of 116 crew members had significant antibody titers to L. pneumophila serogroup 1. One clinically suspected case of legionnaires' disease and one confirmed case were subsequently diagnosed among passengers cruising on the same ship in November 1995 and October 1996, respectively. This is the first documented evidence of the involvement of a water supply system in the transmission of legionella infection on ships. These cases were identified because of the presence of a unique international system of surveillance and collaboration between public health authorities.

Legionella pneumophila is an important pathogen that may cause nosocomial and community-acquired pneumonia in patients with normal or altered immunity. The epidemiology of 40 cases of legionella pneumonia in patients hospitalized between 1986 and 1994 was studied. Fourteen patients (35%) were solid organ transplant recipients. The calculated annual incidence of L. pneumophila infection was highest among lung transplant recipients (2.07 cases per 1,000 transplant-years). There was a trend toward reduced mortality rates and less severe disease among transplant patients vs. nontransplant patients: mortality rate, 36% vs. 54%; incidence of intubation, 50% vs. 69%; rate of concurrent infections, 29% vs. 38%; and overall rate of complications, 86% vs. 96%; respectively. In a multivariate analysis, factors independently associated with an increased mortality rate were nosocomial acquisition, need for intubation, formation of lung abscess or cavitation, and presence of pleural effusion. Thus, despite differing host immune responses, the most important prognostic factors affecting the outcome of legionellosis are nosocomial acquisition and the development of pulmonary complications.

In July 1995 we investigated a pneumonia outbreak in a Pennsylvania town. We conducted epidemiological and molecular microbiological studies to determine the outbreak source and interrupt transmission of disease. Legionnaires' disease (LD) was quickly identified by urine antigen testing, and a newly developed immunohistochemical stain confirmed nosocomial transmission to a hospital inpatient. LD was confirmed in 22 patients. Case-patients were more likely than controls to have been within 1,000 feet of the hospital (matched odds ratio, 21.0; 95% confidence interval, 2.9-368) during the 2 weeks prior to illness. Legionella pneumophila serogroup 1 (Lp-1) was isolated from hospital cooling towers (CTs) and rooftop air samples but not from hospital potable water or community CTs. Hospital CT and air Lp-1 isolates matched all five patient isolates by monoclonal antibody, arbitrarily primed polymerase chain reaction, and pulsed-field gel electrophoresis subtyping. Strategies to prevent LD must include minimizing transmission from CTs.

In August and September 1993, we investigated an outbreak of legionnaires' disease in Fall River, Massachusetts, that involved 11 persons; the attack rate was highest in Flint, a community of Fall River. All cases were infected with Legionella pneumophila serogroup 1 (Lp-1). A case-control study revealed that cases were more likely than matched controls to have visited sites in neighborhood A of Flint. Environmental sampling in Flint found that four of nine aerosol-producing devices sampled contained legionellae; only two, conjoined cooling towers on building A, contained Lp-1. Three independent methods of subtyping--monoclonal antibody subtyping, arbitrary primer polymerase chain reaction, and pulsed-field gel electrophoresis--revealed that Lp-1 isolates from three cases with culture-positive legionnaires' disease matched those from the cooling towers on building A. Water samples from the homes of cases with culture-positive legionnaires' disease contained no legionellae. The results of this epidemiologic and laboratory investigation indicate that the cooling towers on building A were the source of the outbreak of legionnaires' disease and confirm the importance of cooling towers in the transmission of legionnaires' disease.