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Although a variety of infectious diseases existed in the Americas in pre-Columbian times,[1] the limited size of the populations, smaller number of domesticated animals with zoonotic diseases, and limited interactions between those populations (as compared to areas of Eurasia and Africa) hampered the transmission of communicable diseases. One notable infectious disease that may be of American origin is syphilis.[1] Aside from that, most of the major infectious diseases known today originated in the Old World (Africa, Asia, and Europe). The American era of limited infectious disease ended with the arrival of Europeans in the Americas and the Columbian exchange of microorganisms, including those that cause human diseases. European infections and epidemics had major effects on Native American life in the colonial period and nineteenth century, especially.
Afro-Eurasia was a crossroad among many distant, different peoples separated by hundreds, if not thousands, of miles. But repeated warfare by invading populations spread infectious disease throughout the continent, as did trade, including the Silk Road. For more than 1,000 years travelers brought goods and infectious diseases from the East, where some of the latter had jumped from animals to humans. As a result of chronic exposure, many infections became endemic within their societies over time, so that surviving Europeans gradually developed some acquired immunity, although they were still vulnerable to pandemics and epidemics. Europeans carried such endemic diseases when they migrated and explored the New World.
Europeans often spread infectious diseases to Native Americans through trading and settlement efforts, and these could even be transmitted far from the sources and colonial settlements, including through exclusively Native American trading transactions. Warfare and enslavement also contributed to disease transmission. Because their populations were historically hygienic and had not been previously exposed to most of these infectious diseases, the Native American people rarely had individual or population acquired immunity and consequently suffered very high mortality. The numerous deaths disrupted Native American societies. This phenomenon is known as the virgin soil effect.[2]
- ^ a b Martin, Debra L; Goodman, Alan H (January 2002). "Health conditions before Columbus: paleopathology of native North Americans". Western Journal of Medicine. 176 (1): 65–68. doi:10.1136/ewjm.176.1.65. ISSN 0093-0415. PMC 1071659. PMID 11788545.
- ^ Crosby, Alfred W. (1976), "Virgin Soil Epidemics as a Factor in the Aboriginal Depopulation in America", The William and Mary Quarterly, 33 (2), Omohundro Institute of Early American History and Culture: 289–299, doi:10.2307/1922166, JSTOR 1922166, PMID 11633588