Although we can only speculate about the number of Indians living in the highlands of Ecuador before 1534, we can be certain of the ferocious destruction that accompanied the arrival of smallpox and measles. In order to comprehend the effects of these previously unknown infections and how they influenced the colonial experience of Ecuador's native inhabitants, we must first delineate the disease environment that existed before Europeans arrived. But it is equally important to understand pre-Columbian concepts regarding health, illness, and healing, because they too helped to determine the responses of Indian communities not only to invasion by Old World pathogens but also to the Spanish colonial system as it developed in the northern Andes.

The pathological setting

The most significant difference between patterns of disease in the Old and New Worlds was the absence of many “crowd-type” illnesses in pre-Columbian America. Native Americans had never experienced epidemics of smallpox, measles, influenza, bubonic plague, or cholera – all diseases that require dense human populations in which to proliferate. When the ancestors of American Indians crossed the Bering Strait they brought many diseases with them, but the cold of the far north and the rigors of the journey ensured that some of these organisms or their insect vectors died out.Even after permanent agricultural communities developed, population levels remained too low to sustain acute infections that relied on direct human transmission for their propagation.

Another factor contributing to the paucity of crowd-type diseases was the absence of domesticated mammals living in close proximity to human settlements.