Category Archives: Legionnaires’ disease

Research – Legionnaires’ disease – Annual Epidemiological Report for 2020 Research –

ECDC

CDC legionella

Executive summary

  • Legionnaires’ disease remains an uncommon and mainly sporadic respiratory infection with an overall notification rate of 1.9 cases per 100 000 population for the EU/EEA in 2020.
  • A small decrease in the annual notification rate was observed, down from the 2.2 cases per 100 000 population reported in 2019.
  • Notification rates remained heterogenous across the EU/EEA, varying from fewer than 0.5 cases per 100 000 population to 5.7 cases per 100 000 population, with the highest rate reported by Slovenia.
  • Four countries (France, Germany, Italy and Spain) accounted for 72% of all notified cases.
  • Males aged 65 years and older were most affected (7.1 cases per 100 000 population).
  • The number of reported cases to the travel-associated surveillance scheme decreased by 67% in 2020 compared with 2019.
  • Only 10% of cases were culture confirmed (10%), likely leading to underestimation of disease caused by Legionella species other than Legionella pneumophila.

Research – Influence of Metal Concentration and Plumbing Materials on Legionella Contamination

MDPI

Legionella colonization of water supply pipes is a significant public health problem. The objective of this work was to evaluate Legionella colonization in hotel hot water systems and to investigate the relationship between metal concentrations, piping materials (galvanized iron pipes and plastic pipes), and Legionella proliferation. Concentrations of calcium and magnesium ions and the presence of Legionella pneumophila were determined in a total of 108 water samples from the hot water systems of four hotels in Split-Dalmatia County over a 12-month period, and additional data on piping materials were collected. L. pneumophila was isolated in 23.1% of all samples—in 28.8% (15/52) of water samples from galvanized iron pipes and in 17.8% (10/56) of samples from plastic pipes. L. pneumophila serogroups 2–14 were isolated from all samples. This study found higher prevalence of L. pneumophila at higher concentrations of Ca and Mg ions (except for Mg and plastic pipes). The metal parts of the water supply may be important factors in Legionella contamination due to the possibility of lime scale or roughness of the pipes. Higher Ca and Mg ion concentrations increased the risk of Legionella colonization. View Full-Text

ECDC – Legionnaires’ disease – Annual Epidemiological Report for 2020

ECDC

ECDC’s annual surveillance reports provide a wealth of epidemiological data to support decision-making at the national level. They are mainly intended for public health professionals and policymakers involved in disease prevention and control programmes.

Executive summary

  • Legionnaires’ disease remains an uncommon and mainly sporadic respiratory infection with an overall notification rate of 1.9 cases per 100 000 population for the EU/EEA in 2020.
  • A small decrease in the annual notification rate was observed, down from the 2.2 cases per 100 000 population reported in 2019.
  • Notification rates remained heterogenous across the EU/EEA, varying from fewer than 0.5 cases per 100 000 population to 5.7 cases per 100 000 population, with the highest rate reported by Slovenia.
  • Four countries (France, Germany, Italy and Spain) accounted for 72% of all notified cases.
  • Males aged 65 years and older were most affected (7.1 cases per 100 000 population).
  • The number of reported cases to the travel-associated surveillance scheme decreased by 67% in 2020 compared with 2019.
  • Only 10% of cases were culture confirmed (10%), likely leading to underestimation of disease caused by Legionella species other than Legionella pneumophila.

Research – Innovative Antibiofilm Smart Surface against Legionella for Water Systems

MDPI

Legionella pneumophila contamination of water systems is a crucial issue for public health. The pathogen is able to persist in water as free-living planktonic bacteria or to grow within biofilms that adhere to and clog filters and pipes in a water system, reducing its lifespan and, in the case of hospital buildings, increasing the risk of nosocomial infections. The implementation of water management is considered to be the main prevention measure and can be achieved from the optimization of water system architecture, notably introducing new materials and strategies to contrast Legionella biofilm proliferation and so prolong the water system functionality. In this research, we propose a new smart surface against L. pneumophila biofilm formation. This is based on an innovative type of coating consisting of a sulfonated pentablock copolymer (s-PBC, commercially named Nexar™) deposited on top of a polypropylene (PP) coupon in a sandwich filter model. The covering of PP with s-PBC results in a more hydrophilic, acid, and negatively charged surface that induces microbial physiological inhibition thereby preventing adhesion and/or proliferation attempts of L. pneumophila prior to the biofilm formation. The antibiofilm property has been investigated by a Zone of Inhibition test and an in vitro biofilm formation analysis. Filtration tests have been performed as representative of possible applications for s-PBC coating. Results are reported and discussed.

Research – Vehicle Windshield Wiper Fluid as Potential Source of Sporadic Legionnaires’ Disease in Commercial Truck Drivers

CDC

Abstract

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.

Legionnaires’ disease is a severe form of acute pneumonia caused by inhalation of aerosols containing Legionella bacteria. Most Legionella infections are related to contaminated artificial water systems. Systems with warm water (35°C), stagnation, and lack of disinfection and maintenance can lead to proliferation of Legionella spp. . Cooling towers, warm water systems, and whirlpool spas are well-established sources of infection . However, in most sporadic cases, the source of infection remains unknown.

Commercial truck drivers are at increased risk for Legionnaires’ disease. Exposures related to the vehicle are usually considered secondary to outside sources in industrial areas, such as cooling towers, and are seldomley investigated, despite some studies suggesting them as potential sources. Using windshield wiper fluid without added screen wash has been identified as a risk factor for Legionnaires’ disease in commercial drivers in a previous case‒control study. In addition, Legionella spp. can grow in windshield wiper fluid that does not contain screen wash. However, no studies have epidemiologically confirmed the fluid as the source of infection. We report 2 cases of Legionnaires’ disease cases diagnosed by urine antigen testing (UAT) linked to detection of the bacteria in the windshield wiper fluid.

Research – Rising Incidence of Legionnaires’ Disease and Associated Epidemiologic Patterns, United States, 1992–2018

CDC

Abstract

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.

Research – Legionellosis: A novel mechanism by which the bacterium Legionella pneumophila regulates the immune response of its host cells

Science Daily

Legionellosis or Legionnaires’ disease affected more than 1 800 people in France in 2019 and caused 160 deaths. This emerging disease is caused by Legionella pneumophila, an environmental bacterium that thrives in hot water systems. Researchers have discovered a mechanism that allows Legionella pneumophila to target the immune response of the cells it infects by secreting a small regulatory RNA. This mechanism, not described before, facilitates the survival and proliferation of Legionella pneumophila during infection. The work provides precious information on the strategies used by bacteria to manipulate their host cells.

Research – Emerging Legionella species data

HPS

Legionella_Plate_01

08 February 2022

Article: 56/502

In July 2021, the Legionella Control Association (LCA), in conjunction with the Health and Safety Executive (HSE), Public Health England (PHE) and local authorities, held a webinar aimed at raising awareness of increasing Legionella positivity rates post lockdown.  The data demonstrated that the average positive rate in the UK had increased by around 2% following the lockdowns in response to COVID-19.

To investigate if there were particular species that could have led to this increase, LCA approached the three commercial laboratories in the UK that use MALDI-ToF to confirm down to species level, and asked if they would share their data. This information has now been returned by some laboratories, with findings from over 70,000 positive result samples in a two-year period revealing:

  • over 53% of the results were L.anisa
  • over 32% of the positives were L. pneumophilia, both SeroGroup 1 and SeroGroup 2-15
  • nearly 1% of positives were for L. rubilucens
  • over 6.5% of the results did not confirm a species type
  • there were over a dozen other species identified in results that accounted for less than 1% of the data set

The first line clinical diagnostic tool used to confirm Legionnaire’s disease in the UK is commonly a urinary antigen test (UAT), and this method looks predominantly for L. pneumophilia SeroGroup 1. Given the data LCA has provided so far, this could potentially mean missing over 70% of Legionella infections in patients. It should be highlighted that this data is in its infancy, and LCA state that further research needs to take place before any significant changes are considered or undertaken.

Source: LCA, January 2022

Research – Bacterial Antagonistic Species of the Pathogenic Genus Legionella Isolated from Cooling Tower

MDPI

Legionella pneumophila is the causative agent of Legionnaires’ disease, a severe pneumonia. Cooling towers are a major source of large outbreaks of the disease. The growth of L. pneumophila in these habitats is influenced by the resident microbiota. Consequently, the aim of this study was to isolate and characterize bacterial species from cooling towers capable of inhibiting several strains of L. pneumophila and one strain of L. quinlivanii. Two cooling towers were sampled to isolate inhibiting bacterial species. Seven inhibitory isolates were isolated, through serial dilution plating and streaking on agar plates, belonging to seven distinct species. The genomes of these isolates were sequenced to identify potential genetic elements that could explain the inhibitory effect. The results showed that the bacterial isolates were taxonomically diverse and that one of the isolates may be a novel species. Genome analysis showed a high diversity of antimicrobial gene products identified in the genomes of the bacterial isolates. Finally, testing different strains of Legionella demonstrated varying degrees of susceptibility to the antimicrobial activity of the antagonistic species. This may be due to genetic variability between the Legionella strains. The results demonstrate that though cooling towers are breeding grounds for L. pneumophila, the bacteria must contend with various antagonistic species. Potentially, these species could be used to create an inhospitable environment for L. pneumophila, and thus decrease the probability of outbreaks occurring. View Full-Text

Research – Legionellosis: Diagnosis and Control in the Genomic Era

CDC

CDC legionella

Hundreds of books and textbook chapters, and thousands of journal review articles, have been published on Legionnaires’ disease and Legionella spp. bacteria over the past 45 years, making it important to decide whether this new and quite expensive compilation of reviews is worth acquiring (Figure). The field has become so specialized that even those who know one aspect of it may need a good review of other aspects to easily catch up on recent trends. The book contains chapters on the freshwater ecology of the bacterium; molecular and pathogenic aspects of virulence-associated bacterial secretion systems; very selected aspects of epidemiology; clinical aspects and treatment; laboratory diagnosis; and strain typing methods from serologic to whole-genome sequencing. Some chapters are more current than others. The most recent references for several chapters were published in 2016, and only 1 chapter cites references published in 2020. The book is lightly edited; some of the chapters contain overlapping material, but overall it has few typographical or spelling errors. Not all of the figures are properly labeled; for example, the figure legends in chapter 6 are reversed, and not all of the figure legends in chapter 3 fully explain the meanings of different colors and abbreviations.

I found that several of the chapters contained quite useful information that would be hard to find elsewhere, including a thorough review of L. pneumophila virulence secretory systems, as well as a review of the freshwater ecology of the bacterium, the clinical microbiology and clinical significance of Legionella spp. other than L. pneumophila, and regulatory and risk management strategies for control of the disease. Other readers, depending on their fields of interest and expertise, will find other chapters of particular interest. The chapter on non–whole-genome sequencing methods for strain typing for epidemiologic investigation is well done and could be of interest for those trying to dissect the older literature. Missing from the book, presumably by design, are a chapter reviewing in detail the ecology of the bacterium in the built environment, practical guidance on outbreak investigation, advanced techniques in epidemiologic source investigation, molecular and cellular pathogenesis other than secretion systems, and the molecular evolution of the bacterium, all of which can be found in other sources.

Is this book good value for money? Perhaps not for those who have a narrow interest in a specific field, because there are more up-to-date reviews on many of the topics in journal articles and some textbooks. For those who want to gain an overview of the topics covered in the book, some of which are more comprehensive than those found in textbooks or recent reviews, this may be a useful addition to their libraries.