Differential Seasonality of Legionnaires' Disease by Exposure Category

Seasonal Dynamics and Legionellosis-Associated Hospitalization in Spain: A Retrospective Study

Legionellosis is a serious respiratory disease with a high mortality rate, particularly if it is untreated or occurs in the immunocompromised. Legionellosis must be reported in the Spanish Epidemiological Surveillance System. To optimize the epidemiologic knowledge of legionellosis and improve prevention, we have investigated whether the disease is associated with seasonality. This study has described legionellosis cases, the temporal trend by seasonality, hospitalization rate, case fatality rate, and costs by autonomous community and season. We retrospectively reviewed cases of legionellosis, documented patient and clinical characteristics, diagnostics, and seasonality of infection. This study combined national legionellosis notification and hospital discharge data that were linked via the Spanish National Health Service to provide a dataset of hospitalized cases occurring between 2002 and 2021 in Spain. There was a significant increase in the number of legionellosis cases due to the season of the year in Spain. An association between legionellosis and factors related to seasonality is suggested. An increasing trend in case fatality rate, seasonality, and regionality and a decrease in legionellosis hospitalization in Spain were identified. The characterization of changes in legionellosis trend and seasonality and timely synchronization and harmonization of hospitalization records are essential to strengthen disease monitoring and inform potential interventions in an epidemiological way.

Uncovering Gaps in Knowledge: A Survey of Belgian General Practitioners' Awareness of Legionnaires' Disease Diagnostic Testing

Background: The incidence of Legionnaires' disease (LD) is increasing steadily in Europe. Its early diagnosis by general practitioners (GPs) is crucial for better patient outcomes. Study objectives: This study assessed Belgian GPs' knowledge about LD and the accessibility of diagnostic tests in their practices. Methods: A specifically designed questionnaire was distributed to actively practicing GPs, including primary care trainees, between 31 January 2022 and 13 March 2022. This survey targeted approximately 4200 GPs with an estimated population catchment of 30% of the actively working Belgian GPs. Results: The response rate was estimated at 3%. Over 70% of the GPs correctly identified the LD occurrence peak, major risk factors, and clinical manifestations. While 62% of participants preferred the Legionella pneumophila urinary antigen test (UAT) as a primary diagnostic method, 75% were unsure about its availability within their laboratories and 82% had not prescribed it in the last year. Finally, 76% expressed a desire for additional information on this topic. Conclusions: Belgian GPs should evaluate the possibility of conducting UAT testing in their laboratories to enhance LD case management and improve their preparedness. Furthermore, initiatives should be implemented to improve communication between specialists and GPs and develop educational programs directed at Belgian GPs.

Legionnaires' Disease in Occupational Settings: A Cross-Sectional Study from Northeastern Italy (2019)

In Italy, Legionnaires' Disease (LD) causes >1000 hospital admissions per year, with a lethality rate of 5 to 10%. Occupational exposures could reasonably explain a substantial share of total cases, but the role of Occupational Physicians (OPs) in management and prevention of LD has been scarcely investigated. The present survey therefore evaluates the knowledge, attitudes and practices (KAP) regarding LD from a convenience sample of Italian OPs, focusing on their participation in preventive interventions. A total of 165 OPs were recruited through a training event (Parma, Northeastern Italy, 2019), and completed a specifically designed structured questionnaire. The association between reported participation in preventive interventions and individual factors was analyzed using a binary logistic regression model, calculating corresponding multivariable Odds Ratio (aOR). Overall, participants exhibited satisfactory knowledge of the clinical and diagnostic aspects of LD, while substantial uncertainties were associated epidemiological factors (i.e., notification rate and lethality). Although the majority of participating OPs reportedly assisted at least one hospital (26.7%) and/or a nursing home (42.4%) and/or a wastewater treatment plant, only 41.8% reportedly contributed to the risk assessment for LD and 18.8% promoted specifically designed preventive measures. Working as OPs in nursing homes (aOR 8.732; 95% Confidence Intervals [95%CI] 2.991 to 25.487) and wastewater treatment plants (aOR 8.710; 95%CI 2.844 to 26.668) was associated with participation in the risk assessment for LD, while the promotion of preventive practice was associated with working as an OP in hospitals (aOR 6.792; 95%CI 2.026 to 22.764) and wastewater treatment plants (aOR 4.464, 95%CI 1.363 to 14.619). In other words, the effective participation of the OP in the implementation of preventive measures appears uncommon and is limited to certain occupational settings. Collectively, these results highlight the importance of tailoring specifically designed information campaigns aimed to raise the involvement of OPs in the prevention of LD in occupational settings other than healthcare.

Legionnaires' disease in the EU/EEA*: increasing trend from 2017 to 2019

BackgroundThe burden of Legionnaires' disease (LD) in the European Union/European Economic Area (EU/EEA) has increased during the last decade, with notification rates increasing from 1.2 to 1.4/100,000 population in 2012-16, to 1.8-2.2 within 2017-19.AimTo measure weekly excess cases during 2017-19 based on previous trends and determine whether a significant change in trend occurred, and to examine any differences in age, sex or level of imported infections.MethodsWe collated 2012-19 annual surveillance data from The European Surveillance System (TESSy) reported by EU/EEA countries. A retrospective prediction by a dynamic regression model was created from 2012-16 data to assess excess cases in 2017-19. Interrupted time series (ITS) analysis was performed to determine if a significant change in trend occurred in 2017-19 compared with the previous 5 years.ResultsWe found a 33.9% increase in cases in 2017-19 compared with the number predicted. The ITS also found a significant trend increase in 2017-19 compared with 2012-16. A significant trend increase was observed from 2017 most strongly among older age groups (> 60 years) and non-imported cases.ConclusionOur study showed a significant increasing trend in LD cases in the EU/EEA during 2017-19 compared with the previous 5 years. The distribution of cases per week suggests an overall amplification of the seasonal trends. These findings underscore that LD continues to be an infectious disease of public health concern in the EU/EEA, warranting further research into determinants of the increase.

Epidemiology of Legionnaires' Disease in Italy, 2004-2019: A Summary of Available Evidence

Legionnaires’ disease (LD) incidence has been increasing in several European countries since 2011. Currently, Italy is experiencing high notification rates for LD, whose cause still remains scarcely understood. We sought to summarize the available evidence on the epidemiology of LD in Italy (2004–2019), characterizing the risk of LD by region, sex, age group, and settings of the case (i.e., community, healthcare, or travel-associated cases). Environmental factors (e.g., average air temperatures and relative humidity) were also included in a Poisson regression model in order to assess their potential role on the annual incidence of new LD cases. National surveillance data included a total of 23,554 LD cases occurring between 2004 and 2019 (70.4% of them were of male gender, 94.1% were aged 40 years and older), with age-adjusted incidence rates increasing from 1.053 cases per 100,000 in 2004 to 4.559 per 100,000 in 2019. The majority of incident cases came from northern Italy (43.2% from northwestern Italy, 25.6% from northeastern Italy). Of these, 5.9% were healthcare-related, and 21.1% were travel-associated. A case-fatality ratio of 5.2% was calculated for the whole of the assessed timeframe, with a pooled estimate for mortality of 0.122 events per 100,000 population per year. Poisson regression analysis was associated with conflicting results, as any increase in average air temperature resulted in reduced risk for LD cases (Incidence Rate Ratio [IRR] 0.807, 95% Confidence Interval [95% CI] 0.744–0.874), while higher annual income in older individuals was associated with an increased IRR (1.238, 95% CI 1.134–1.351). The relative differences in incidence between Italian regions could not be explained by demographic factors (i.e., age and sex distribution of the population), and also a critical reappraisal of environmental factors failed to substantiate both the varying incidence across the country and the decennial trend we were able to identify.