Pre-Columbian civilizations lived in a sort “genetic isolation,” unlike the Old World Civilizations. Europeans, Asians and Africans contacted often spreading diseases around and therefore growing a resistance to certain illnesses. Although evidence from skeletal remains of Native American show illnesses, the rate of infection was not alarming as in the Old Word. Even at the peak of population for the Native Americans it was not enough to develop endemic infections, even when nomadic lifestyle could easily encourage spreading of an infection. It is also important to note that the population density for urban population was lower compared to that of the Old World Civilization. In addition, the contact between domesticated animals and Native Americans was different compared to the same contact in the Old World. Limited contact for the Native Americans kept diseases at bay and many of the animals who spread infection to humans came with or after Columbus. Dorothy Porter explains that Llamas as a herd animals pose little risk to Native Americans as oppose to the herd animals -cattle that the Old World used for planting.
Furthermore, Native Americans made great strides in healing/curing which aided in curtailing the spread of infection and the rate at which it passed from person to person. According to Albert S. Lyons, Montezuma kept a well stocked nursery of medicinal plants for the use of the entire Aztecs kingdom. There were medicines for diarrhoea, for skin diseases, narcotics and drugs which cast off evil spirit by sweating, purging and vomiting. The Incas also invested in plant remedies. They used quinine, effectual for malaria fever and coca leaf used to stimulate and calm. It is interesting to note that many pharmaceutical products borrow from the Incas plant remedies.
The diet of the Native Americans also aided in maintaining a healthy frame from many illnesses. For example, the mixture of agricultural products with beans and maize kept many Native Americans from suffering from a deficiency of vitamins, avoiding illnesses such as scurvy or pellagra.
In addition, to diet the cleanliness of urban areas kept Native Americans fecal infection at a minimum. Before Cortes invasion of Tenochtitlan, the city is known as a clean sanctuary which differ from many European cities at that time. The conquistador Bernal Diaz describes the city’s sewerage system from collection to disposal. There were public latrines in each street and the collected waste went outside city boundaries for burial. Each district cleaned their streets. With a system for cleanliness, it kept parasite illnesses at bay.