Reading about Chagas’ disease in Bolivia gives a perspective for understanding this disease throughout Latin America and for predicting what might happen in the United States and Europe, where it is spreading. Chagas’ disease is the space in which are encapsulated minutely infinite forces and from which we might get a broader perspective of the universe.
CHAPTER ONE
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.
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.
Malaria Closes Brazilian Ports
On March 30, 1905, the Santos Dock Company of Santos, near Sao Paulo, Brazil, hired Carlos Chagas to combat malaria. Its workers were so weakened by fever that they could not complete the port of Santos, the most important in Brazil. Carlos Chagas accepted the challenge to do fieldwork (“trabalhar no campo”) and to observe firsthand malaria within its natural and social environment. Chagas used his first paycheck to buy a microscope; he then had the only tool needed to examine the microcosm.
Carlos Chagas’ earlier studies of malaria and later studies of Chagas’ disease stimulated new concepts of these diseases that incorporated parasitology, entomology, and human physiology while studying relationships of parasites, vectors, and hosts. Vectors are carriers, usually arthropods or insects, that transmit causative organisms of disease, parasites, from infected to noninfected individuals. A parasite usually goes through one or more stages in its life cycle within the vector. The host is the organism in which parasites obtain nourishment and reproduce. Knowledge of the parasitic cycles enhances our understanding of tropical diseases and their relationship to the environment.
Carlos Chagas disagreed with the then-current practices of pouring toxic substances on lakes, reservoirs, and stagnant water to eliminate malaria. Doctors had used this method in Panama and Cuba under the assumptions of marasmus theory that attributed malaria to vapors. Chagas recognized that the use of smoke, toxic substances, and the drainage of swamps were ineffective remedies because they destroyed only the larvae of the mosquito. He also objected that such methods destroyed fish and reptiles and could never be applied to all the ponds, lakes, and waterholes in the tropics.
Because mosquito larvae are not infected with parasites, Carlos Chagas’ strategy against malaria in 1905 was to attack the adult vectors by preventing uninfected (also sometimes called sterile) mosquitos from coming into contact with infected humans and infected mosquitos from coming into contact with healthy humans (Chagas 1935). Chagas observed that after mosquito vectors acquire their fill of blood, they lose the ability to take off in flight and can hardly fly over the walls and furniture of a house to begin digestion of the ingested blood (Chagas Filho 1993:78). He advocated closing off houses with doors and screens and disinfecting houses by burning pyrethrum from chrysanthemum flowers, which kills mosquitos in flight.
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1. For the medical history of Chagas’ disease see Chagas 1909, 1911, 1921, 1922, 1988; Chagas Filho 1959, 1968, 1988, 1993; Kean 1977; and Lewinsohn 1979, 1981.