Inca Expansion and the Spread of Chagas’ Disease

Medical anthropologists can interpret how sociocultural factors contribute to the parasitic cycle of Chagas’ disease. Inca civilization illustrates this. Often compared to the Romans, Incas are famous for their conquests, empire building, architecture, and treatment of diseases (see Lumbreras 1974, Rowe 1946, and Zuidema 1964). These achievements influenced the transmission of T. cruzi and the treatment of its syndromes. The Inca empire extended from Chile to Ecuador, and from the Pacific Ocean into the Amazon. An extensive road network was established between colonies. During the empire’s height in the fifteenth century several hundred ethnic groups and thousands of communities exchanged resources, ranging from parrots of the Amazon in Ecuador, Peru, and Bolivia to salt from the high Atacama desert in Argentina and Chile.

When Incas expanded their empire from Cuzco to Bolivia, Chile, and Ecuador, T. infestans rapidly spread to communities across the Andes, providing an example of biotic exchange following “civilizing” forces. T. infestans became a commensal species (such as mice), living in close proximity to humans. Houses provided proximity to animals and humans and a protected habitat from the cold. Unknowingly, Incas transported vinchucas in llama caravans throughout the empire.

During the expansionist fifteenth century in Incaic America, Pacha Kuteq Inca Yupanki, the ninth king, conquered the Chanka, a powerful neighboring kingdom, and his son, Tupac Inca Yupanki, extended the empire from the Mapuche line in central Chile to Quito, Ecuador, as well as westward to the coast and eastward to the Amazon. The Inca empire was named Tawantinsuyo for four triangulated sections that were formed with the bases of the triangle at Cuzco, the apexes extending to the four directions: two long‑sided isosceles triangles pointing north and south, and short‑sided triangles pointing east and west.

The Inca present a unique example of how a mountain civilization was able to incorporate many ecological zones and cultures within a continent. During the Incario there was a massive exchange of people, cultures, resources, animals, plants, insects, and parasites. Only within the last twenty years has there been a comparable ethnic and biotic exchange within the Andes.

The Andes are characterized by their verticalityas one travels up a mountain, the width of the ecological band decreases. Climbing an Andean mountain, one finds tropical leafy plants, monkeys, and parrots in the lower valleys; corn, vegetables, and fruits on the lower slopes, potatoes, oca, and barley on the central slopes; alpacas, llamas, and bunch grass on the higher slopes; and mossy and furry plants on the tundra near the summit. Andean communities live, farm, and herd in these zones. They then exchange resources with others, often relatives, from communities at another level. For example, highland Aymara herders raise alpacas and llamas at 15,000 feet whose meat they exchange to Quechua farmers at lower levels who raise potatoes, and to other farmers at still lower levels who grow corn.

The Incas moved mitmakuna, colonists, from each of the several hundred ethnic groups to different regions of the Andes as well as to different elevations. These colonists expanded the groups’ access to products throughout the Andes. The Incas profited politically by being able to better control each group, now weakened at home by the exportation of members and by the settlement within the ethnic group of Inca administrators. The ethnic groups were not entirely unhappy, however, because mitmakuna opened up the possibility of exchanging resources with many different regions. The Incas demanded portions of all produce for the state, to be stored in warehouses and used in times of famine and war. An elaborate system of roads, runners (chasquis ), quipus (knotted cords used to keep records), warehouses, and military posts linked the communities with the capital, Cuzco, and each other.

Chagas’ disease increased with this exchange of people and resources that had previously been restricted to smaller levels of the region. The Incas brought herbalists and ritualists to Cuzco from the Lake Titicaca region for medicinal purposes. Especially recognized, the Kallawayas, now located in Province Bautista Saavedra, Charazani, Bolivia, carried the chair of the Inca king and practiced herbal medicine in Cuzco and other parts of the Incario (Bastien 1987a, Oblitas Poblete 1968, 1969, 1978). (Kallawaya treatments for Chagas’ disease are discussed in the next chapter.)