This project aims at investigating transnational medical collaborations at the beginning of the 20th century, and their repercussions on the constellations of social demarcation in the prevailing countries. These medical practices were framed by interconnected nationalistic and eugenic concepts, originating from the interdependence of the conceptions of “race”, gender and class. By relating Brazilian, Portuguese and German discourses about human Trypanosomiases, the underlying conceptions of national and “racial” identity and especially their mutual influence shall be analyzed; considering the fact that Portuguese and German colonialisms and Brazilian discourses were based on opposing eugenic ideas: ideas of segregation in Germany, ideas of assimilation in Portugal, and ideas of “degeneration” and “whitening” in Brazil. Being a sickness of the lower social classes in Brazil, and a colonial disease in Africa, both types of Trypanosomiases were considered diseases of the “racial other”, thus offering an interesting analysis of contemporaneous concepts of “otherness” and of the alterations they underwent in the transnational context. Concerning Brazil, the impact of its participation in European “white” discourses on inner-social constellations of in- and exclusion shall be analyzed.