Oswaldo Cruz’s Scientific Correspondence covers much of his professional life, from 1899 to 1916, and portrays the network of relations he formed with Brazilian and foreign scientists, especially the mentors with whom he studied in Paris. The earliest records from this collection refer to the period when he was in the port of Santos, São Paulo, helping combat a bubonic plague outbreak that had erupted there and was threatening to reach Rio. It was there that Cruz struck up a friendship with Vital Brazil; their ensuing exchange of letters depicts the challenging process of establishing Brazil’s two serum therapy institutes, the Butantan, in São Paulo, and the federal, in Rio de Janeiro. Their correspondence also attests to the era’s scientific controversies over the production of plague serum, including the question of how best to modify the Haffkine vaccine in order to arrive at a safe dose.
Early on in his days as head of the General Directorate of Public Health, Cruz found himself in the middle of another controversy, this one about the transmission of yellow fever and how to prevent and combat the malady. He exchanged much correspondence with the three French scientists from the Pasteur Mission to Brazil: Alexandre Salimbeni, Paul-Louis Simond, and Émile Marchoux. At the close of their three-year stay in Brazil (1901-1904), the French researchers wrote an in-depth report in which they confirmed the theory of transmission by the mosquito Stegomyia fasciata and recommended that yellow fever be fought by combating the insect’s breeding grounds and larvae.