American Trypanosomiasis, known as Chagas disease, was discovered in 1909 under peculiar circumstances: its discoverer, Carlos Chagas, was sent to a small village of Central Brazil to carry out an anti-malaria campaign when he came across a blood sucking insect--the vector for the parasite infection. He had been alerted to the coincidence of peculiar symptoms and the presence of this insect in the wood and earth dwellings of the region. He was deeply involved in theoretical controversies in international protozoology; he was engaged in the consolidation of a scientific role and corresponding institutional conditions in Brazil, and equally immersed in the nationalist sanitary struggles of his days. In these contexts, Chagas assembled a remarkable discovery discourse, regarding the biology of the parasite, its life cycle and mode of transmission. Furthermore, he provided the clinical description of a new disease. Despite immediate international recognition, however, the unstable institutional arrangements surrounding his work damaged its local legitimacy for decades. His authority was widely recognized abroad, but rejected at home.