This article discusses the relationship between the production of scientific knowledge on filariasis in Brazil and health policy-making and implementation related to control of the disease. The study presents a review of scientific output on filariasis from the creation of the Program to Combat Filariasis in the mid-20th century until the creation of the Unified National Health System (SUS) within the framework of decentralized control of endemic diseases in the country. The focus on empirical observations in Recife, a city where filariasis is present, highlights the relevant institutional processes and the role of various players. The hypothesis is that in the first half of the 20th century there was a lack of scientific knowledge and technological development to control the problem, but that after these advances were obtained, new requirements of a political nature came into play and acted as determinants for persistence of the endemic in the city.