(Photo: Janice Haney Carr/CDC)

Information for Participants

Legionnaires' disease (LD) is a severe form of pneumonia that is caused by Legionella bacteria. Infections with this bacterium are notifiable and must be reported by the physician to the Federal Office of Public Health (FOPH). The number of these notifications has more than doubled between 2014 and 2021. Unfortunately, it is unknown why more and more people are contracting LD and where they get infected. Our study team aims to better understand possible risk factors and sources of infection for Legionnaires' disease. We would also like to learn more about the individual disease experience and recovery of Legionnaires' disease patients.

What can you expect if you participate in the study?

The study team will contact you by phone in the next few days. If you decide to participate in the study, we will arrange an interview lasting approximately 45-60 minutes. During the interview, we will ask you questions about your health, your living situation, your activities and your habits (e.g. have you been on holiday, do you garden a lot, do you have pets?). In addition, we will ask your physician whether Legionella bacteria have been isolated from your lung secretion and (if found) will analyze them. We would also like to ask you again later about the course of your recovery.

For some, but not all patients, we ask for permission to collect and test water samples e.g. from their kitchen and bathroom. This will allow us to compare Legionella strains from the environment with the Legionella strain found in your lung secretion.

You can also contact the study team directly at any time with questions or to make an appointment.

Legionella bacteria may be found anywhere in the water or the soil. Although Legionella bacteria can be found ubiquitously and thus many people are in contact with them, only some people get sick. We do not know why this is the case. Therefore, it is important that we can compare healthy study participants with Legionnaires’ disease patients.

The study team will contact you by phone in the next few days. If you decide to participate in the study, we will arrange an interview lasting approximately 45-60 minutes. During the interview, we ask you questions about your health, your living situation, your activities and your habits (e.g. have you been on holiday, do you garden a lot, do you have pets?).

For some participants we ask for permission to collect and test water samples from their kitchen and bathroom. This helps us to better understand where Legionella bacteria are found in the environment and compare them to Legionella bacteria that can cause pneumonia.

You can also contact the study team directly at any time with questions or to make an appointment.

What are your benefits if you participate?

By participating in the study, you will have the opportunity to learn more about Legionnaires' disease and also help us to understand it better. In doing so, you will help the Federal Offices to take measures to prevent the risk of Legionnaires' disease in the future. You also help us to better understand the course of recovery and the potential long-term health impacts of Legionnaires' disease.

Do you have any questions?

Please do not hesitate to contact us by phone or email or consult our frequently asked question section on our webpage. We look forward to hearing from you.

Tel No.: +41 61 284 88 50
Email: info.swisslegioswisstph.ch

Frequently Asked Questions

You will first speak to a SwissLEGIO staff member by telephone. This will allow us to discuss the eligibility requirements again and explain the study process to you. Next, we will set a date for the first interview together with you. This can take place at a location of your choice. On the day of the interview, we will be happy to go through the aims of the study, the procedure and your rights and obligations with you again in detail and answer any questions you may have. We will then ask you to sign a written consent form.

If you agree, we may contact you again after this initial interview to (i) collect water samples from your home and (ii) enquire about your well-being again at a later date.

You do not have to visit Swiss TPH at any point in the study.

If you were asked to participate by Swiss TPH or your physician, the answer is usually yes! If you are over 18 years old, are living in Switzerland, did not stay overnight in a hospital and were not on holiday for more than seven days in the last two to three weeks, you are usually eligible. A SwissLEGIO employee will be happy to discuss the inclusion and exclusion criteria with you again individually either by telephone or by e-mail.

Although the cantonal authorities know about our study, their investigations are independent of our study. We would therefore be very pleased if you still participate in our study despite having already answered an initial survey by the cantonal authorities.

If you have any questions about the differences between the survey of the cantonal authorities and our study, please do not hesitate to contact our study team.

We know that it takes time to recover from Legionnaires' disease. Our SwissLEGIO team is therefore aware that you may not have fully recovered.  Therefore it is in principle possible to participate at a later date. However, the earlier you participate, the better.

In the case of Legionella infections, it is important to be able to find out as quickly as possible where you have potentially been infected and then collect water samples there if necessary. In addition, we will ask you what you did in the two weeks prior to the disease. The sooner we can do this, the easier it will be for you to remember. Therefore, we would appreciate your timely participation.

Our SwissLEGIO team will of course be considerate during the interview. You can take a break at any time during the interview or cancel the interview and continue on another day. You are also welcome to have a family member with you during the interview. Furthermore, we will only contact you if your health condition has been assessed by a specialist and an interview is justifiable from a medical point of view.

Your data is strictly protected under Swiss and European law and we ensure that we follow all these regulations accurately. During data collection your data is encoded. Encoding means that all data that could identify you (name, date of birth, etc.) is deleted and replaced by a code. Persons who do not have access to this key list can therefore not draw any conclusions about your person. All SwissLEGIO staff members are bound by professional secrecy.

A case-control study starts with the identification of persons with the disease interest (“cases”) and a suitable control group of persons without the disease (“controls” ). In this study Legionnaires’ disease patients are our cases, healthy participants from the general population are our control. By comparing cases and controls we aim to identify risk factors that may be associated with Legionnaires’ disease.

We are happy to receive your questions about the SwissLEGIO study! If you have any questions about our study, please contact our study team by e-mail (info.swisslegioswisstph.ch) or by phone (+41 61 284 88 50). We look forward to hearing from you.

We would be happy to inform you about the results of our study. Please write us an email (info.swisslegioswisstph.ch) or call us (+41 61 284 88 50) to give us your contact details and we will inform you about results.

Please consult the information leaflet that was sent to you jointly with the results. There you find some hints on how you can further proceed. You may always contact the SwissLEGIO study team if you need help to understand the results or if you would like us to connect you to a specialist for further investigations (e-mail: info.swisslegioswisstph.ch or Tel. +41 61 284 88 50)

Please note that the study team is not authorized to do any further assessments beyond the scope of the research project. We thank you for your understanding.

The SwissLEGIO study team (from left to right: Julia Fanderl, Manuel Wiederkehr, Natascha Roser, Daniel Mäusezahl, Melina Bigler, Lucie Prêtre and Fabienne Fischer)