[Paul-Louis Simond and the Marchoux mission in Brazil]. / Paul-Louis Simond et la mission Marchoux au Brésil.

In 1900 the role of a particular mosquito called Stegomyia fasciata in the transmission of yellow fever was proved by a board of American medical officers. This discovery was the beginning of several scientific missions in South America, mostly in Brazil. As yellow fever was increasing in its West African colonies, the French government decided to send a scientific mission to Rio de Janeiro, to find new ways of prevention against the disease. Under the authority of the Institut Pasteur, Paul-Louis Simond, who had just discovered the role of the flea in the transmission of plague, was designated to carry through this mission together with Emile Marchoux and Alexandre Salimbeni, eminent Pasteurians like him. From November 1901 to May 1905, the three men studied the epidemiological and clinical aspects of the disease in Rio. They worked on the intermediate host's entomology, the Stegomyia female mosquito, improving the knowledge of yellow fever and its means of transmission. They also realized experiments on 25 healthy volunteers, submitting them to the bite of infected mosquitoes. They were among the first to proceed to yellow féver vaccinations by means of virulent serum heated to 55 degrees C or filtered. Their work led to the establishment of new sanitary rules to prevent the spread of the disease. This contributed to the success of the "yellow fever campaign" initiated by Oswaldo Cruz in the town of Rio. One of the most original contribution of their studies was to show that the yellow fever agent (which was still unknown) could be transmitted from an infected female Stegomyia to its eggs and larvaes. After this mission, the French authorities were able to fight yellow fever efficiently in their African colonies as well as in the West Indies and French Guyana.