Imprimir Republish


On their own skin

106 years ago, Emilio Ribas and Adolpho Lutz proved that yellow fever was transmitted by mosquitoes


History Museum of the University of São Paulo Medical SchoolThe former Isolation Hospital in 1899: setting for experimentsHistory Museum of the University of São Paulo Medical School

At the end of 1901, Rodriguez Alves, the president of the State of São Paulo, authorized the Sanitation Authorities to repeat a controversial medical experiment conducted in Cuba. At that time, the island – under the rule of the United States – was facing a serious yellow fever epidemic resulting in a high mortality rate. The sanitation works had not produced the expected effect and the disease was resistant to eradication. The current medical opinion at that time was that the infection was caused by microorganisms that exist in mildew and air contaminated by other patients. However, since 1881, Cuban physician Carlos Finlay had defended the theory that the disease was transmitted by the Stegomyia fasciata mosquito (renamed Aedes aegypti in 1926), but  he had never been taken seriously by the international scientific community. In 1900, a committee of sanitary specialists from the U.S. Army, headed by bacteriologist Walter Reed, was sent to Cuba and, in view of the inefficiency of the traditional methods, decided to test Finlay’s hypothesis. When evidence proved that Finlay’s hypothesis was correct, measures were taken to eradicate the S. fasciata on the island.  In six months, the epidemic was eradicated.

Brazil had also been hit by yellow fever epidemics. Physician Emílio Marcondes Ribas (1862-1925), director of the Sanitation Department in São Paulo since 1898, was an attentive reader of international news. “Unlike Adolpho Lutz and Oswaldo Cruz, who had studied abroad, Ribas was a clinician whose academic studies had been entirely conducted in Brazil;  however, he always corresponded with sanitation experts from abroad”,  says Marta de Almeida, a researcher on the history of science from the Museu de Astronomia e Ciências Afins/Mast science and astronomy museum. The city of São Paulo had not been affected by the epidemic, but some regions in the state, such as the cities of Santos and Campinas, were. In Rio de Janeiro, the capital city of the nation, the epidemic was a serious health issue, 58.063 deaths were registered from 1850 to 1902 in the city alone.

“Ribas was a firm believer in Finlay’s thesis and had already been battling the S. fasciata in the state”, says Marta. But he was opposed by some physicians, who did not believe in this form of transmission. When Ribas heard about the Cuban case, he believed he could replicate in São Paulo what had been done in Havana as a way of effectively participating in investigations on yellow fever. Authorized by the government, he conducted the first phase of the experiment from December 15, 1902 to January 20, 1903. Together with Lutz, director of the Instituto Bacteriológico institute, he subjected himself to being bitten by mosquitoes that had been infected by a light case of yellow fever. Four other volunteers (Oscar Moreira, Domingos Pereira Vaz, André Ramos and Januário Fiori) did the same. The first three did not develop any symptoms, probably because they were already immune to the disease, as they had traveled to regions where the disease was endemic. Vaz, Ramos and Fiori were infected.

The second phase of the experiment took place in 1903. The control group, with three Italian volunteers, was shut in a room for 20 days; the rooms, which were protected from mosquitoes, were filled with clothes and objects sullied by urine, vomit and feces of patients ill with the disease. None of these volunteers got sick. The experiment was supervised by a medical committee, which supported the result.  Both experiments were conducted at the Hospital de Isolamento de São Paulo hospital, located next to the Instituto de Bacteriologia institute (renamed Instituto Adolpho Lutz). Later on, the former isolation hospital was expanded to become the Instituto de Infectologia Emílio Ribas, Infectious Diseases Institute.

The experiments conducted in Cuba and São Paulo provided support for the highly successful prophylactic campaigns in the country.  In 1936, U.S. scientists Max Theiler and Henry Smith developed an efficient vaccine from a virus strain; no cases of yellow fever have been registered in urban areas since 1942. The news on recent cases all refer to cases in rural areas.