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The Impact of European Diseases on Native Americans

The Impact of European Diseases on Native Americans


Contact between Europeans and Native Americans led to a demographic disaster of unprecedented proportions. Many of the epidemic diseases that were well established in the Old World were absent from the Americas before the arrival of Christopher Columbus in 1492. The catastrophic epidemics that accompanied the European conquest of the New World decimated the indigenous population of the Americas. Influenza, smallpox, measles, and typhus fever were among the first European diseases imported to the Americas. During the first hundred years of contact with Europeans, Native Americans were trapped in a virtual web of new diseases. European diseases, seeds, weeds, and animals irreversibly transformed the original biological and social landscape of the Americas. By 1518, the Native American demographic catastrophe and the demands of Spanish settlers for labor led to the importation of slaves from Africa. Thus, the Americas quickly became the site of the mixing of the peoples and infectious agents of previously separate continents.


Despite considerable progress in analyzing traces of the early migrations to the Americas, there is still doubt about the time of the arrival of the first humans. Some scholars believe that wandering bands of hunter-gatherers first crossed a land bridge from Asia to the New World about 10,000 years ago. Other evidence suggests that human beings might have arrived much earlier, but the earliest sites are very poorly preserved. In any case, migration from Siberia to Alaska might have served as a "cold filter" that screened out many Old World pathogens and insects. In addition, except for the late development of a few urban centers, primarily in Mesoamerica, population density in the New World rarely reached the levels needed to sustain epidemic diseases.

Centuries before Europeans arrived in the Western Hemisphere, advanced cultures and great cities had developed in Guatemala, Mexico, and the Andean Highlands. These areas were not free from disease, but accounts of pre-Conquest epidemics were generally associated with famines. Archeological evidence suggests that there were several periods of significant spurts of population growth and sudden declines in the Americas long before European contact. However, the impact of European diseases and military conquest was so profound and sudden that other patterns of possible development were abruptly transformed. Contact events involving the Aztecs, Mayans, and Inca civilizations were especially dramatic, primarily because Mexico and Peru had the highest population densities and the most extensive trade and transport networks in the Americas. Such factors provide ideal conditions for the spread of epidemic diseases.

Initial European reports about the New World speak of a veritable Eden, populated by healthy, long-lived people, who could cure illness with indigenous medicinal plants, and did not know the diseases common in other parts of the world. Of course, the New World was not really a disease-free utopia. Diseases that were probably present in pre-Columbian America included American leishmaniasis, American trypanosomiasis (Chaga's disease), roundworms, pinworms, tapeworm, treponematosis, tuberculosis, arthritis, cancer, endocrine disorders, dysentery, pneumonia, rickettsial and viral fevers, goiter, and pinta.

Smallpox, measles, chicken pox, whooping cough, diphtheria, scarlet fever, trachoma, malaria, typhus fever, typhoid fever, influenza, cholera, bubonic plague, and probably gonorrhea and leprosy were unknown in the precontact period. The pre-Columbian distribution of certain diseases, especially syphilis and yellow fever, is still controversial, although some physicians believed that Europeans imported syphilis from the New World. Because yellow fever can be confused with malaria, dengue fever, or influenza, early accounts of such epidemics are unreliable. Modern immunological and entomological studies seem to have eliminated earlier claims that Mayan civilization was virtually destroyed by yellow fever, or that epidemics of this disease occurred in Vera Cruz and San Domingo between 1493 and 1496. Some epidemiologists contend that yellow fever was brought to the New World from Africa and that the first known epidemic occurred in Cuba in the seventeenth century.


Although a precise determination of the population of the Americas in 1492 is probably impossible, there is no doubt that contact with Europeans resulted in a massive demographic collapse of the Native American population. The magnitude of the collapse and its causes remain controversial. Assessing the impact of European contact is a not simple matter because changes in population are the result of complex forces. Some scholars have argued that the devastating population decline in the New World was due primarily to imported diseases, while others have argued that the demographic catastrophe was the result of the chaos and exploitation that followed the Conquest. The rapid decline in the numbers of Native American peoples and the demands of Spanish settlers for labor, led to the establishment of the transatlantic slave trade by 1518. The Americas became the site of an unprecedented mixing of peoples and infectious agents from previously separate continents.

Although it is impossible to quantify with any certainty the impact of European contact on New World populations, estimates of the pre-contact population of the Americas have ranged from 8 to 30 million. Between 1492 and 1650 the Native American population may have declined by as much as 90% as the result of virgin-soil epidemics (outbreaks among populations that have not previously encountered the disease), compound epidemics, crop failures and food shortages.

The first Spaniards to reach the Caribbean islands found at least four distinct Indian cultures. Some recent estimates suggest that the pre-Columbian population of Hispaniola (modern Dominican Republic and Haiti) was close to 4 million. By 1508, fewer than 100,000 Indians remained. By 1570, almost all of the Caribbean Indians had disappeared, except for the Caribs in a fairly isolated area of the eastern Caribbean. A similar pattern occurred in Cuba, which was conquered in 1511.

Even before the first appearance of smallpox in the Caribbean, some epidemic disease seems to have swept through the islands and devastated the Indians of Hispaniola, Cuba, and the Bahamas. The first epidemic disease to attack the Caribbean Indians might have been swine influenza, brought to the West Indies in 1493 with pigs that Columbus had obtained from the Canary islands on his second voyage. Typhus may also have attacked the islands before the first known smallpox outbreaks in Hispaniola in 1518 and Cuba in 1519. Smallpox decimated the Arawaks of the West Indies, before making its way to Mexico with the Spaniards, and preceding them into the Inca Empire. The Spanish estimated that death rates among Native Americans from smallpox reached 25 to 50%. A similar death rate occurred in Europe, but the disease had essentially become one of the common childhood diseases. Therefore, most adults were immune to the disease. Other European diseases seem to have reached the islands before the measles epidemic of 1529. More recent examples of virgin soil outbreaks suggest that the mortality rate for swine influenza is about 25%, smallpox about 40%, measles about 25%, and typhus between 10 and 40% of the affected population.

With the establishment of the transatlantic slave trade by 1518, diseases from Africa were added to the epidemic burden imposed on Native Americans. The vector and virus for yellow fever probably appeared in San Juan, Puerto Rico by 1598. Better-documented outbreaks occurred on Barbados and Guadeloupe, Cuba, and the Gulf coasts of Mexico and Central America in 1647. Soon after the original human inhabitants of the islands were gone, the native plants and animals were forced to compete with Old World invaders. The peoples of the present day Caribbean trace their ancestry principally to Asia, Europe, and Africa. Slaves were imported as early as 1502, but by 1518 the decline in labor supply had become so acute that King Charles I of Spain approved the direct import of slaves from Africa. However, the Africanization of the islands was the result of the "sugar revolution" that began in the seventeenth century, along with the importation of epidemic yellow fever.

The Empire of the Aztecs was the first American civilization to encounter the Spanish and the first to be destroyed. Several factors, including devastating epidemics of smallpox, which killed many Aztec warriors and nobles, facilitated the Spanish capture of the Aztec capital in 1521. Native Americans came to see this smallpox epidemic as a true turning point in their history. The time before the arrival of the Spanish was remembered as a veritable paradise, free of fevers, smallpox, stomach pains, and tuberculosis. When the Spanish came, they brought fear and disease wherever they went. Mayan civilization had already experienced a long period of decline by the time it encountered European explorers and invaders, but the Inca Empire was at its peak when the Spaniards conquered it in 1532.

European diseases probably preceded European contact in the Andean region. A catastrophic epidemic, which might have been smallpox, swept the region in the mid-1520s, killing the Inca leader Huayna Capac and his son. Subsequent epidemics struck the region in the 1540s, 1558, and from the 1580s to 1590s. These waves of epidemic disease might have included smallpox, influenza, measles, mumps, dysentery, typhus, and pneumonia. The precise impact of smallpox and other European diseases throughout the Americas is difficult to document or comprehend. However, studies of more recent and limited virgin soil outbreaks clearly demonstrate how small a spark is needed to create a great conflagration in a native population.


Further Reading

Ashburn, Percey Moreau. The Ranks of Death: A Medical History of the Conquest of America. New York: Coward-McCann, Inc., 1947.

Cook, Nobel David. Born to Die: Disease and New World Conquest, 1492-1650. (New Approaches to the Americas.) New York: Cambridge University Press, 1998.

Crosby, Alfred W. The Columbian Exchange: Biological and Cultural Consequences of 1492. Westport, CT: Greenwood Press, 1972.

Crosby, Alfred W. Germs, Seeds, and Animals: Studies in Ecological History. Armonk, NY: M.E. Sharpe, 1993.

Denevan, William M. The Native Population of the Americas in 1492. Madison, WI: University of Wisconsin Press, 1976.

Dobyns, Henry F., with W.R Swagerty. Their Number Became Thinned: Native American Population Dynamics in Eastern North America. Knoxville, TN: University of Tennessee Press, 1983.

Henige, David. Numbers from Nowhere: The American Indian Contact Population Debate. Norman, OK: University of Oklahoma Press, 1998.

Kunitz, Stephen J. Disease and Social Diversity: The European Impact on the Health of Non-Europeans. New York: Oxford University Press, 1994.

Ramenofsky, Ann F. Vectors of Death: The Archaeology of European Contact. Albuquerque, NM: University of New Mexico Press, 1987.

Reff, Daniel T. Disease, Depopulation, and Culture Changes in Northwestern New Spain, 1518-1764. Salt Lake City, UT: University of Utah Press, 1991.

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