Surveillance of Legionella spp. in Open Fountains: Does It Pose a Risk?

Clusters of outbreaks or cases of legionellosis have been linked to fountains. The function of fountains, along with their inadequate design and poor sanitation, in combination with the warm Mediterranean climate, can favor the proliferation of Legionella in water systems. Public fountains in Mediterranean cities may pose a significant risk for public health due to the aerosolization of water. Nevertheless, few studies have been conducted on Legionella and the risk of infection in humans through fountains. In our study, the presence and quantity of Legionella spp. in fifteen external public fountains were investigated. Two samplings were performed in two different periods (dry and wet). Sixty samples were collected, quantified and analyzed with a culture ISO method. The operation of all fountains was evaluated twice using a standardized checklist. In accordance with their operation, a ranking factor (R factor) was suggested. Finally, based on these results, a quantitative microbial risk assessment was performed. Thirty water samples taken from the fountains (100%) during the dry sampling period were positive for Legionella (mean log concentration: 3.64 ± 0.45 cfu/L), whereas 24 water samples taken from the fountains during the wet period were Legionella-positive (mean log concentration: 2.36 ± 1.23 cfu/L). All fountains were classified as unsatisfactory according to the checklist for the evaluation of their function. A statistically significant correlation was found between Legionella concentration and the assessment score. The risk of Legionella infection was estimated in both periods, with higher risk in the dry period. The surveillance and risk assessment of Legionella spp. in the fountains of Patras confirmed a high prevalence and a high risk to public health.

Legionellosis risk-an overview of Legionella spp. habitats in Europe

An increase in the number of reports of legionellosis in the European Union and the European Economic Area have been recorded in recent years. The increase in cases is significant: from 6947 reports in 2015 to 11,298 in 2019. This is alarming as genus Legionella, which comprises a large group of bacteria inhabiting various aquatic systems, poses a serious threat to human health and life, since more than 20 species can cause legionellosis, with L. pneumophila being responsible for the majority of cases. The ability to colonize diverse ecosystems makes the eradication of these microorganisms difficult. A detailed understanding of the Legionella habitat may be helpful in the effective control of this pathogen. This paper provides an overview of Legionella environments in Europe: natural (lakes, groundwater, rivers, compost, soil) and anthropogenic (fountains, air humidifiers, water supply systems), and the role of Legionella spp. in nosocomial infections, which are potentially fatal for children, the elderly and immunocompromised patients.

Dispersion of Legionella bacteria in atmosphere: A practical source location estimation method

Legionnaires’ disease, a form of pneumonia which can be fatal, is transmitted via the inhalation of water droplets containing Legionella bacteria. These droplets can be dispersed in the atmosphere several kilometers from their source. The most common such sources are contaminated water within cooling towers and other air-conditioning systems but other sources such as ornamental fountains and spa pools have also caused outbreaks of the disease in the past. There is an obvious need to locate and eliminate any such sources as quickly as possible. Here a maximum likelihood model estimating the source of an outbreak from case location data has been developed and implemented. Unlike previous models, the average dose exposure sub-model is formulated using a atmospheric dispersion model. How the uncertainty in inferred parameters can be estimated is discussed. The model is applied to the 2012 Edinburgh Legionnaires’ disease outbreak.

Trends in Gastric and Esophageal Cancer Incidence in Northern Portugal (1994-2009) by Subsite and Histology, and Predictions for 2015

Introduction

Gastric cancer (GC) and esophageal cancer (EC) share risk factors, and the incidence trends reflect differences in etiology according to their subtypes. We aimed to describe the incidence trends of GC (by topography) and EC (by histological type) in northern Portugal for 1994-2009 and to estimate the incidence for 2015. We further analyzed exposure to the main risk factors for these cancers in the region over the last decades.

Methods

GC and EC data were obtained from the North Region Cancer Registry of Portugal (RORENO). Joinpoint regression was used to compute annual percent changes (APC) in incidence trends. Poisson regression yielded estimates for 2015. A literature review up to 2014 provided data on exposure to risk factors.

Results

GC rates decreased in 1994-2009 (men, APC = −1.3; women, APC = −1.6); GC, unspecified subtype, had the steepest decline since the early 2000s (men, APC = −4.9; women, APC = −6.3). The incidence for 2015 will increase for EC in men (up to ≈190 cases) and stabilize in women (≈30) and for GC (≈730 men, ≈500 women). Increasing prevalence of tobacco smoking among women and overweight/obesity, fairly stable prevalence of alcohol, fruit and vegetable consumption, and no trend for Helicobacter pylori infection were observed.

Conclusions

The declining incidence of GC unspecified subtype indicated an improvement in cancer registration accuracy, but precluded a sound assessment of trends by subtype. Variations in the prevalence of exposure to some risk factors were consistent with observed incidence trends, and future studies should aim to quantify their contribution to the GC and EC burden in the region.

Confirmed and Potential Sources of Legionella Reviewed

Legionella bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires' disease. This review provides an overview of reservoirs of Legionella reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of Legionella. A total of 17 systems and matrices could be classified as confirmed sources of Legionella. Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious Legionella bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of Legionella. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden.

Current and emerging Legionella diagnostics for laboratory and outbreak investigations

Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.

Health risk assessment for splash parks that use rainwater as source water

In the Netherlands, rainwater becomes more and more popular as an economic and environmentally sustainable water source for splash parks, however, the associated public health risk and underlying risk factors are unknown. Since splash parks have been associated with outbreaks of infectious diseases, a quantitative microbial risk assessment was performed using Legionella pneumophila as a target pathogen to quantify the risk of infection for exposure due to inhalation and Campylobacter jejuni for ingestion. Data for L. pneumophila and C. jejuni concentrations in rainfall generated surface runoff from streets were extracted from literature. Data for exposure were obtained by observing 604 people at splash parks, of whom 259 were children. Exposure volumes were estimated using data from literature to determine the volume of exposure through inhalation at 0.394 μL/min (95% CI-range 0.0446-1.27 μL/min), hand-to-mouth contact at 22.6 μL/min, (95% CI-range 2.02-81.0 μL/min), ingestion of water droplets at 94.4 μL/min (95% CI-range 5.1-279 μL/min) and ingestion of mouthfuls of water at 21.5·10(3) μL/min (95% CI-range 1.17 ·10(3)-67.0·10(3) μL/min). The corresponding risk of infection for the mean exposure duration of 3.5 min was 9.3·10(-5) (95% CI-range 0-2.4·10(-4)) for inhalation of L. pneumophila and 3.6·10(-2) (95% CI-range 0-5.3·10(-1)) for ingestion of C. jejuni. This study provided a methodology to quantify exposure volumes using observations on site. We estimated that using rainwater as source water for splash parks may pose a health risk, however, further detailed quantitative microbial analysis is required to confirm this finding. Furthermore we give insight into the effect of water quality standards, which may limit infection risks from exposure at splash parks.

A cluster of cases of nosocomial legionnaires disease linked to a contaminated hospital decorative water fountain

BACKGROUND

Nosocomial outbreaks of Legionnaires disease have been linked to contaminated water in hospitals. Immunocompromised patients are particularly vulnerable and, when infected, have a high mortality rate. We report the investigation of a cluster of cases of nosocomial pneumonia attributable to Legionella pneumophila serogroup 1 that occurred among patients on our stem cell transplantation unit.

METHODS

We conducted a record review to identify common points of potential exposure, followed by environmental and water sampling for Legionella species from those sources. We used an air sampler to in an attempt to detect aerosolized Legionella and pulsed-field gel electrophoresis to compare clinical and environmental isolates.

RESULTS

The most likely sources identified were the water supply in the patients' rooms and a decorative fountain in the radiation oncology suite. Samples from the patients' rooms did not grow Legionella species. Cultures of the fountain, which had been restarted 4 months earlier after being shut off for 5 months, yielded L. pneumophila serogroup 1. The isolates from both patients and the fountain were identical by pulsed-field gel electrophoresis. Both patients developed pneumonia within 10 days of completing radiation therapy, and each reported having observed the fountain at close range. Both patients' infections were identified early and treated promptly, and both recovered.

CONCLUSIONS

This cluster was caused by contamination of a decorative fountain despite its being equipped with a filter and ozone generator. Fountains are a potential source of nosocomial Legionnaires disease despite standard maintenance and sanitizing measures. In our opinion, fountains present unacceptable risk in hospitals serving immunocompromised patients.

Restaurant outbreak of Legionnaires' disease associated with a decorative fountain: an environmental and case-control study

Background

From June to November 2005, 18 cases of community-acquired Legionnaires' disease (LD) were reported in Rapid City South Dakota. We conducted epidemiologic and environmental investigations to identify the source of the outbreak.

Methods

We conducted a case-control study that included the first 13 cases and 52 controls randomly selected from emergency department records and matched on underlying illness. We collected information about activities of case-patients and controls during the 14 days before symptom onset. Environmental samples (n = 291) were cultured for Legionella. Clinical and environmental isolates were compared using monoclonal antibody subtyping and sequence based typing (SBT).

Results

Case-patients were significantly more likely than controls to have passed through several city areas that contained or were adjacent to areas with cooling towers positive for Legionella. Six of 11 case-patients (matched odds ratio (mOR) 32.7, 95% CI 4.7-∞) reported eating in Restaurant A versus 0 controls. Legionella pneumophila serogroup 1 was isolated from four clinical specimens: 3 were Benidorm type strains and 1 was a Denver type strain. Legionella were identified from several environmental sites including 24 (56%) of 43 cooling towers tested, but only one site, a small decorative fountain in Restaurant A, contained Benidorm, the outbreak strain. Clinical and environmental Benidorm isolates had identical SBT patterns.

Conclusion

This is the first time that small fountain without obvious aerosol-generating capability has been implicated as the source of a LD outbreak. Removal of the fountain halted transmission.

Genetic diversity of Legionella pneumophila inferred from rpoB and dotA sequences

This study characterised the population structure of Legionella pneumophila by comparing the rpoB (300-bp) and dotA (360-bp) sequences of 267 isolates (18 reference strains, 149 Korean isolates and 100 Japanese isolates). In addition to the six clonal subgroups established previously, four subgroups, P-V to P-VIII, were identified. Subgroupings based on rpoB and dotA sequences were found to correlate with the source of the isolates, and this data may be useful for future epidemiological studies. Fourteen (five Korean and nine Japanese) isolates showed incongruent subgroupings in the rpoB and dotA trees, suggesting that genetic exchange among subgroups, and even among subspecies, may occur frequently in nature.