Room
1er étage - E130
Theme
Effective measures against infectious diseases
Chair
Daniel Mäusezahl
Title
SwissLEGIO – Time to act on Legionellosis: Update on a national case-control and molecular source attribution study
Name
Daniel Mäusezahl
Affiliation
Swiss Tropical & Public Health Institute
Abstract
Legionnaires’ disease (LD) is notifiable and a severe form of pneumonia. In the past decade, LD cases more than doubled in Switzerland, reaching an annual notification rate of 7.3 cases per 100,000 population in 2023. In response to this development, the Swiss Federal Offices mandated a national case-control and molecular source attribution study (SwissLEGIO).
SwissLEGIO investigates risk factors and infection sources of community-acquired LD. The study innovates by combining case-control and molecular typing approaches for source attribution on a national level. This work was developed in a fully transdisciplinary manner and is conducted in an interdisciplinary, co-production approach with various governmental and research stakeholders. It further collaborates with 20 university- and cantonal hospitals.
SwissLEGIO achieves a high geographical coverage and the collaboration with the hospitals allows minimising the time from diagnosis to infection source investigations, and improves the availability of clinical Legionella isolates from patients’ lung samples.
We present an update on this national study on LD 1.5 years after first patient recruitment in July 2022. Totally 425 LD cases were notified to the SwissLEGIO study from all greater regions of Switzerland. This corresponds to 45% of all LD patients notified to the FOPH. The overall enrolment rate was 46% (n=193). 23% of the enrolled LD patients were admitted to the ICU. The median time from diagnosis to notification of the study team was 1 day (IQR: 0 - 3 days). The median time between diagnosis and enrolment was 8 days (IQR: 3 - 14 days). For 21% of patients a Legionella isolate could be obtained. This is markedly higher than the Legionella recovery rate prior to the SwissLEGIO study (~5%). For 39% of enrolled LD patients (n=76), an environmental investigation was initiated incl. their homes sampled. Additionally, and in close collaboration with cantonal authorities, seven large public buildings (elderly homes and schools) were sampled. The median time between notification of an LD patient to sampling was 13 days (IQR: 8 - 18 days).
Overall, recruitment of LD patients through the hospital network was highly successful. The study design proved to provide timely and reliable access to LD patients and clinical Legionella isolates facilitating timely source investigation. We present the patients collective and experiences from working with authorities and research partners for the source investigation.
Title
Die Schweiz impft im Blindflug - Lösungsansätze aus Public Health-Sicht
Name
Sang-Il Kim
Affiliation
Berner Fachhochschule
Abstract
Vaccinations are among the most important and cost-effective medical preventive measures. They can prevent diseases and deaths that cause great suffering and high costs. Vaccinations can also help to save indirect costs, such as those arising from disabilities, premature deaths, loss of productivity and antibiotic resistance. In order to realize these savings, the aim should be to achieve the highest possible vaccination coverage for the entire population.
Suitable monitoring systems are needed to measure this goal and to monitor the success of vaccination campaigns. The cantonal vaccination monitoring system currently operated by the FOPH is no longer adequate, as it only covers children and adolescents and no longer provides sufficiently representative data. There is therefore an urgent need for new ways of measuring vaccination coverage in the population as a whole.
During a workshop at the Swiss Public Health Conference 2023, possible solutions were discussed, which are summarized and highlighted in this paper. All stakeholders in the healthcare system, and parliament in particular, are called upon to work together to find ways and implement them as soon as possible so that one of the most effective and cost-effective preventive measures - vaccination - can take effect.
Title
Abundance and characterization of malaria vectors in Sakassou, Central Côte d’Ivoire
Name
Golou Louise Bellai
Affiliation
Swiss Tropical and Public Health Institute
Abstract
Background Prior to the implementation of malaria vector control strategies, assessing mosquito species composition with focus a on malaria vectors including their biting and resting behaviour is a prerequisite. In this study, we provide an updated and descriptive malaria transmission patterns in Sakassou area, central Côte d’Ivoire and build a baseline entomological data for further control interventions. Methods A 19-month longitudinal survey was carried out each month from November 2018 to July 2020 in two houses in urban and rural of Sakassou area using indoors and outdoors human landing catches, pyrethrum spray catches and Centre for Disease Control and Prevention light traps. All collected mosquito were identified morphologically and Anopheles gambiae s.l. species were determined using molecular PCR diagnostics. Plasmodium sporozoite rates were estimated using enzyme-linked Immunosorbent assays. Results In total, 98,727 mosquitoes including 92,158 Anopheline. Mosquito densities increased with the rainfall with high number of mosquitoes collected in the wet season. Anopheles coluzzii was the most prevalent species represented 90% of the catches. High biting rates were recorded and peaking around 1.00 am. Although, this species bite similarly indoors and outdoors. The mean Plasmodium infection rate in An. coluzzii was 0.017 (95% confidence interval: 0.01-0.03). Based on the four houses of HLC, population of Sakassou was exposed to an overall 100, 5 infective bites of An. gambiae s.l. per year). Conclusion An. coluzzii from Sakassou are infected and bite when people are asleep favouring LLINs and IRS in preventing malaria. However, outdoor intervention might also be beneficial. High EIR justified the epidemiological profile of Sakassou as one of the high malaria prevalence district.
Title
SwissLEGIO – Studying infection sources for Legionnaires’ disease using whole genome sequencing
Name
Melina Bigler
Affiliation
Swiss TPH
Abstract
Legionnaires’ disease (LD) is a severe form of pneumonia caused by the ubiquitous but mostly waterborne bacterium Legionella spp. LD is notifiable in all EU and EEA countries. Surveillance data shows that Switzerland has one of the highest notification rates in Europe. The main sources of infection and the cause for this high rate remain largely unknown. This hampers the implementation of targeted Legionella spp. control efforts.
The SwissLEGIO national case-control and molecular source attribution study investigates infection sources for LD in Switzerland. Over the past 1.5 years, we enrolled 200 newly diagnosed LD patients through a nationwide network of 20 secondary- and tertiary hospitals. Healthy controls were recruited from the general population. Risk factors for LD were assessed in questionnaire-based interviews and Legionella spp. was isolated from LD patients’ BAL and sputum samples. We also collected 580 water samples from participants’ homes and other potential infection sources and recovered 439 Legionella spp. isolates that were further characterised. Finally, clinical and environmental Legionella spp. isolates were compared using whole genome sequencing (WGS). Direct comparison of sero- and sequence types (ST), core genome multilocus sequencing types (cgMLST), and single nucleotide polymorphisms (SNPs) between clinical and environmental isolates were used to assess similarities between the isolates and to attribute LD cases to infection sources. This direct comparison revealed two LD clusters in the Ticino.
In the SwissLEGIO study, WGS proved useful for the detection of LD clusters. Nonetheless, using WGS for infection source investigations for a ubiquitous bacterium such as Legionella spp. is challenging. Such challenges relate to the use of appropriate sampling and recovery strategies of Legionella spp. from clinical and environmental samples, but also to biobanking efforts, and to interpreting WGS results. Based on our experiences of applying WGS in the SwissLEGIO study, we discuss the applicability and challenges of WGS as a tool for LD surveillance in Switzerland. By presenting our results from the Ticino, we show how good collaboration among various national authorities and research stakeholders was key for conducting our infection source investigations and how a rich set of epidemiological metadata was particularly powerful in informing our sampling strategies and for the interpretation of our WGS results.
Title
Adherence to antimicrobial treatment guidelines for Legionnaires’ disease – the SwissLEGIO multicentre study
Name
Melina Bigler
Affiliation
Swiss TPH
Abstract
Legionnaires’ disease (LD) is a severe form of primarily community-acquired pneumonia (CAP). The infection-causing Legionella spp. bacteria are intracellular pathogens that require treatment with specific antibiotics exhibiting intracellular penetration. Accordingly, upon confirmation of a Legionella infection, antimicrobial treatment guidelines suggest a discontinuation of beta-lactams and a switch to a targeted monotherapy with quinolones or macrolides. The timely initiation of such appropriate, targeted antibiotics for LD can reduce mortality, antibiotic-related side effects, and contributes to ongoing antimicrobial stewardship efforts. In this study, we assess the appropriateness and timely switch to targeted antimicrobial therapy for LD patients from 20 Swiss secondary and tertiary hospitals of the SwissLEGIO study.
Data on antimicrobial prescriptions are collected for 200 LD patients from electronic health records (median age 68 years, 68% male patients). Appropriateness of antimicrobial use is evaluated according to the Swiss national guidelines for CAP. Currently, 94% of patients received macrolides or quinolones as part of their treatment regimen within one day after a confirmed LD diagnosis. The alignment of antibiotic choices with treatment guidelines improved from 55% for the empirical CAP treatment prior to the availability of LD diagnostic results to 80% within 24 hours after results were available for the targeted LD treatment. Nonetheless, for 14.5% of patients, treatment with beta-lactams was continued for more than 24 hours after the LD was confirmed. Additionally, for 41% of patients, the treatment duration with quinolones or macrolides was longer than the recommended 7-10 days (14-21 days for immunocompromised patients).
Overall, effective antibiotic treatment is initiated with minimal delays after LD is confirmed. A positive LD test also improves adherence to treatments recommended in the national guidelines. Nonetheless, beta-lactams are not always discontinued, and the treatment duration is often longer than recommended.