Columbian Exchange Diseases

The Variola Annihilation: Smallpox in the New World

The greatest killer was smallpox, which was spread by direct human contact.

• Smallpox is a deadly sickness that lasts only briefly in each patient
• After an incubation period of about two weeks, the patient suffers from high fever and vomiting, followed three or four days later by skin eruptions
• If the patient does not die, these pustules dry up in a week and form scabs that fall off, leaving the pocks that give the disease its name
• The process takes a month or less; after that time, the patient is either dead or immune
• There is also no nonhuman carrier of smallpox; it must pass from person to person.

Except for children, most Europeans and their enslaved people had had smallpox and were at least partially immune. Few adults sailed from Europe to America in the first decades after discovery. The voyage took several weeks, so even if an immigrant or sailor contracted smallpox before they set sail, they would most likely be dead or rid of the virus before landfall in the Americas.

Tomonaliztli: Smallpox in the Mexica Empire

The epidemic that hit the Aztec capital of Tenochtitlan in 1520 had begun on the island of Hispaniola two years earlier and had spread through Mexico, Central America, and South America. One of the reasons the Spanish conqueror Pizarro took over the Incan Empire so quickly was that disease had annihilated their society just before his arrival. Smallpox was not the only disease to kill off thousands of native peoples; influenza, measles, and other illnesses added to the destruction of native society.

Columbian Exchange Diseases: Chart

The table below lists the diseases exchanged between the Old World and the New World after the first contact between Europeans and the indigenous peoples of the Americas.

New World Diseases in the Columbian Exchange

The exchange of diseases was not one-sided. The Americans gave Europeans syphilis. The first recorded case of syphilis in Europe occurred in Spain in 1493, shortly after Columbus’s return. Although less deadly than the diseases exchanged in the Americas, syphilis was more virulent in the 1500s than today, and adequate treatment was unknown.

Fig. 2 - This graph shows the rapid collapse and destruction of the indigenous population of Central America after contact with the Spanish.

Columbian Exchange Diseases Diffusion Map

The map below shows the Old World and New World origins of the diseases exchanged between Europe, Asia, Africa, and the Americas.

Fig. 3 - Disease exchange between the New and the Old World. Source: Image created by Author.

The Columbian Exchange Diseases and their Significance

The statistics of the Old-World diseases and their impact on the Americas, even the conservative estimates, are staggering.

Diseases and Their Significance for the Conquest of the New World

The significance of this exchange is difficult to understate. From the first contact with the voyages of Christopher Columbus to the mid-1600s, eighty-five to ninety-five percent of the indigenous populations of the Americas are gone. Though European nations wage military campaigns to take land and resources from these peoples, the diseases and sicknesses Europeans introduced do most of the damage. Entire civilizations will collapse, and cultures will disappear under the burden of epidemics due to population loss. It is the closest thing to what human extinction may look like for historians and anthropologists to study.

Fig. 4 - A depiction from 1598 of the Spanish executing indigenous Americans during their conquest of Central America.

If indigenous civilizations and societies did survive, what is left is usually a remnant of what the culture used to be. The diseases made these societies relatively easy to conquer militarily, as the needed manpower for defense or warfare was nonexistent or depleted. It made communities more susceptible to cultural influence and change as oral and written histories were lost to the surviving generations, opening them to the pressures of conversion and assimilation into the dominant European culture.

Diseases and Their Significance for the Atlantic Slave Trade

One significant unintended consequence of the spread of disease is its influence on the early Atlantic slave trade. As indigenous populations were not immune to disease, European nations did not have a local source of enslaved labor. This lack of labor allowed colonial powers to enter the African slave markets to meet the labor demands in their American territories, as Africans were immune to Old World diseases.