Cruz found that the seaport of Santos was ravaged by an epidemic of bubonic plague that threatened to reach Rio de Janeiro, and engaged himself immediately in the combat of this disease. The mayor of Rio de Janeiro authorized the construction of a plant for manufacturing the serum against the disease which had been developed at the Pasteur Institute by Alexandre Yersin and coworkers. He asked the institution for a scientist who could bring this know-how to Brazil. The Pasteur Institute responded that such a person was already available in Brazil: Oswaldo Cruz.
