In the last sixty years, the number of aid organizations sending aid workers abroad has multiplied. Aid workers were mostly experienced people with some kind of special training in their field of work. In the past two decades a new form of humanitarian work, called volunteering, was established and has since then increased tremendously. In 2008, the so called “Weltwärts” program was founded in Germany, sending young volunteers at the age of 18–28 to social projects worldwide for one year (Anonymous (2021b). This type of intercultural exchange which the young volunteers experience, promotes their personal development but also exposes them to new health risks they are not always aware of. As stated in other studies, “their idealism is often bigger than their risk perception” (Martin et al., 2012) and their risky behavior results in a higher number of frequent tropical infections like malaria (Anonymous, 2020b), dengue, typhoid fever or schistosomiasis (Kiehl, 2011). In order to prevent such diseases, volunteers being send to the tropical regions (tropics) must undergo a mandatory pre-travel medical examination and receive pre-travel health advice (Prüfer-Krämer et al., 2020). This preventive measure has been in effect since 2019.

By law, Weltwärts-volunteers with a German work contract being sent abroad are covered under the labour protection act just like any other workers in Germany (Anonymous, 2008). A suspected diagnosis for a tropical illness during the period of the voluntary work in the tropics must therefore be reported as occupational disease by the doctor and the employer if the procedural requirements according to BK-3104 (Anonymous, 2005) to get such a disease at work are fulfilled. If professional work in the tropics has exposed an employee to diseases that do not exist in Germany and it is likely that the disease was acquired at work and not otherwise, then contracting such a disease is considered a consequence of the work contract and fulfills therefore the procedural requirements as an occupational disease. This so-called “double causality” (diagnosis and exposure at work) may be required e.g. for Hepatitis B when a medical person is working with patients. However, if a diagnosis of Hepatitis B cannot be easily linked to risk exposure at work, e.g. in a bureau job, requirements are not fulfilled. The first case would fulfill the requirement of double causality, the latter normally not. In most countries occupational diseases are listed. In Germany, the diagnoses of tropical occupational diseases investigated in this study are coded as BK-3104.

It has been suspected that occupational diseases by infections occur more frequently among young volunteers than among the comparative group of mostly older aid worker (Martin et al., 2012). However, there is limited data and therefore any strategy to improve medical prevention and health care among young volunteers in the tropics is so far limited.