In 1887, after passing his entrance exam, Oswaldo Cruz enrolled at the Rio de Janeiro School of Medicine. He was 14. Unlike his father, Bento Gonçalves Cruz, he showed no special interest in clinical medicine. From the very beginning, his true passion was microbiology—the science of microorganisms.
Born with the development of microscopy, this new field of knowledge had substantially broadened science’s understanding of the role played by microbes in infectious disease and had thus paved the way for developing new methods of preventing and curing a number of these illnesses. In Europe’s largest cities, microbiology was winning over increasing numbers of proponents thanks to the pioneer work of France’s Louis Pasteur (1822-1895), who, alongside other scientists—like the German Robert Koch (1843-1910)—was radically changing the panorama of medicine and science.
In Brazil, the spread of new ideas had spurred the adoption of a new teaching model in medical schools. Drawing inspiration from the German experience in free, practical instruction, the initiative became known as the Sabóia Reform (1884) in honor of its originator, Vicente Cândido Figueira de Sabóia (1881-1889), then director of the Rio de Janeiro School of Medicine.
One of the reform measures introduced practical instruction to all medical classes. A number of laboratories were then set up for this purpose, while scientific debate was simultaneously encouraged as a complement to the essentially theoretical teaching that had previously predominated at most medical schools. One of the laboratories established at the Rio de Janeiro School of Medicine was part of the chair in hygiene, headed by Prof. Benjamin Antônio da Rocha Faria. It was there that Cruz had his first practical experience in the field of microbiology.
On the recommendation of João Martins Teixeira, professor of the chair in medical physics, Cruz joined the laboratory in 1888. He first served as an assistant specimen technician. Two years later, when the laboratory was transformed into the National Institute of Hygiene, he became an assistant to Rocha Faria.
Cruz received his medical degree on the morning of November 8, 1892. He wrote his graduation thesis on water as a vehicle for the propagation of microbes. He dedicated it to his father, who was to pass away a few hours after Cruz defended it.