Discovering Chagas’ Disease

In 1909 Carlos Chagas discovered American trypanosomiasis by intuition, induction, scientific method, hard work, genius, and a pinch of luck.[4]Carlos Chagas represents a rare example of a medical scientist who described a disease after having found its causative agent, T. cruzi, in the intestines of triatomine insects. He observed its pathogenicity to mammals, located its domestic and wild reservoirs, and then went on to find infected humans. He finally documented its acute and chronic phases. Chagas ranks with the greatest scientists of the twentieth century; Chagas’ disease remains a scourge of this century and a battle of the next.

Chagas’ discovery coincided with conquests of the Amazon. It was a time when symbiotic microorganisms, living in animal reservoirs within the Amazon, became pathogenic for invading settlers. Such is now the case for Bolivians with Chagas’ disease.

As a budding parasitologist in that discipline’s age of discovery, Carlos Chagas realized that microbiology could reveal the causes of tropical diseases. The microscope was to biology what the telescope was to astronomy. Within a generation, scientists had discovered the world of microbiology and shattered many age‑old aetiologies: Robert Koch discovered the tuberculin bacterium in 1882 and liberated tuberculosis from its association with consumption, vapors, and “bad air.” Louis Pasteur isolated the rabies virus and produced an attenuated strain or vaccine in 1884. Pasteur disproved the notion that the disease resulted from nervous trauma allegedly suffered by sexually frustrated dogs (rabid men were said to be priapic and sexually insatiable) (Geison 1995:179; Kete 1988). D.D. Cunningham described leishmania organisms found in skin lesions in India in 1885; F. Schaudinn depicted trophozoites and cysts of Entamoeba histolytica (amoebic dysentery) in 1903 (dying at thirty‑five as a result of his self‑experimentation). R.M. Forde showed that Trypanosoma bruceigambiense caused sleeping sickness in 1902, providing a pathogenic agent rather than African laziness as its cause. The microscope did for the minuscule world what the telescope did for the universe: it changed beliefs in origins of disease and cosmic phenomena. The sequel to these discoveries, however, is that tropical diseases remain as prevalent as ever. The impoverished tropics aren’t considered profitable enough for the investment of wide‑scale remedies. The spectacular research mentioned above was primarily for the health of colonialists and workers in industrial expansion.

^{Figure 2.}

^{Carlos Chagas examining parasites under the microscope at the Oswaldo Cruz Institute in Rio de Janeiro, where he studied in 1902. (Photo from Renato Clark Bacellar, Brazil’s Contribution to Tropical Medicine and Malaria, Rio de Janeiro, 1963)}

Carlos Justiniano Ribeiro Chagas was born on July 9, 1879, in the small town of Oliveira, Minas Gerais, Brazil, of Portuguese farmers who were descendants of immigrants who had come to Brazil in the late seventeenth century (Lewinsohn 1981). His upper‑class parents owned a small coffee plantation with a modest income. When he was four, his father died, and his mother, a strong‑willed farmer, raised him and three younger children. She tried to persuade him to become a mining engineer, but he refused and instead chose medical school, being swayed by a physician uncle who convinced him that for Brazil to develop industrially it was necessary to rid the country of endemic diseases. (Many European ships refused to dock in Brazilian ports because of fear of contracting yellow fever, smallpox, bubonic plague, and syphilis).

Carlos Chagas studied at the Oswaldo Cruz Institute in 1902, where he wrote his M.D. thesis on the “Hematological Aspects of Malaria” (1903) under the leading Brazilian parasitologist, Oswaldo Cruz. Cruz tackled the task of ridding Rio de Janeiro of yellow fever by the systematic combat of the mosquito vector and the isolation of victims in special hospitals. He also provided vaccinations against the plague and smallpox. Eradication of vectors and mass vaccinations were revolutionary measures at this time. Many diseases were thought to be caused by vapors emanating from the hot and humid earth, such as mal de aire (“evil from the air”) or malaria. Cruz was successful fighting yellow fever in Rio, and similar methods also decreased the disease in Panama for the building of the canal. However, Cruz’s fight against mosquitos in Brazil continued for years.

When Cruz invited Chagas to work on malaria research, Chagas refused, saying that he was not cut out to do research and preferred to practice family medicine. Chagas worked in a hospital at Jurujuba from 1903 until 1905, where he introduced antipest serotherapy, which Cruz had modified from that introduced by Louis Pasteur in France around 1890. Pasteur led the way in germ therapy in opposition to theories of spontaneous generation as principles of life and causes of diseases (see Geison 1995). Following Pasteur’s and Cruz’s assumptions that negative organic elements fermented positive organic elements, Chagas first prepared an antipestic serum, then cut into a patient’s swollen glands and inserted this serum to destroy the “peste” (see Chagas Filho 1993). Chagas was a very innovative and experimental doctor who looked for answers in practice rather than in the laboratory.