The range of illnesses observed upon return from the tropics remains poorly understood despite their prevalence: approximately 50 million people travel to developing countries each year, 25 to 64% experience a health problem during their stay, and 8 to 19% seek medical care upon their return. The respective proportions of tropical (so-called imported) and cosmopolitan diseases are unclear: data sets devoted to specific disease groups (fever, skin diseases, respiratory diseases, etc.) show a predominance of cosmopolitan diseases; studies focused on specific imported diseases (malaria, schistosomiasis, leishmaniasis, etc.) do not provide a clearer picture of the spectrum of infectious and tropical diseases observed, a topic that has been the subject of very few studies. (Introduction)