The
arrival and settlement of Europeans in the Americas resulted in what is known
as the Columbian exchange. During this period European settlers brought many
different technologies, animals, plants, and lifestyles with them and also took
plants and goods back to the Old World.
But
Europeans also unintentionally brought new infectious diseases including,
smallpox, bubonic plague, chickenpox, cholera, the common cold, diphtheria, influenza,
malaria, measles, scarlet fever, typhoid, typhus, tuberculosis, and whooping
cough. The Europeans infected with such diseases typically carried them in either
a dormant state, were actively infected but asymptomatic, or had only mild
symptoms. As a result, the explorers and colonists often unknowingly passed the
diseases to the Indigenous peoples.
Europe
was a crossroads between many distant, different peoples from Asia, Africa and
the Middle East. In spite of the vast distances, repeated warfare by invading
populations had, over the years, spread infectious disease throughout the
continent, as did trade. 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, over time many infections became endemic within Eurasian
societies and, surviving Europeans gradually developed some acquired immunity,
although they were still subject to pandemics and epidemics. Europeans carried
these endemic diseases with them when they migrated to the New World.
Native
Americans contracted infectious disease through trading and exploration
contacts with Europeans, and these in turn were transmitted far from the original
sources and colonial settlements. Warfare and enslavement also contributed to
disease transmission. Because their populations had not been previously exposed
to these infectious diseases, the Indigenous people rarely had any acquired
immunity and consequently suffered a very high mortality rate when they got
infected.
Smallpox
was the disease brought by Europeans that was most destructive to the Native
Americans. The first well-documented smallpox epidemic in the Americas began in
Hispaniola in late 1518 and soon spread to Mexico. Estimates of mortality
range from 25% - 50% of the population of central Mexico. After
its introduction to Mexico in 1519, the disease spread across South America,
devastating Indigenous populations during the sixteenth century.
It was first reported in New France in
1616 near Tadoussac, the
colony’s first fur-trading post.
The budding fur trade repeatedly exposed nearby Montagnais and Algonquin communities
to the disease. Many fell ill and died due to their lack of immunity. The
disease then spread into the Maritimes, James Bay, and Great Lakes regions.
Between 1634 and 1640, Jesuit priests
inadvertently introduced smallpox into the Huron community west of Lake Simcoe and
south of Georgian Bay. Due to
smallpox and other infectious diseases the Huron population had declined in
1640 by roughly 60%.
It was
introduced to eastern North America by colonists arriving in 1633 to Plymouth,
Massachusetts, and local Native American communities were soon struck by the
virus. It reached the Mohawk nation in 1634, the Lake Ontario area in
1636, and the lands of other Iroquois tribes by 1679. By 1698 the
virus had crossed the Mississippi, causing an epidemic that nearly obliterated
the Quapaw Indians of Arkansas.
As European fur-trading posts moved west, so did
the virus. From 1779 to 1783, smallpox spread to areas that now form parts of
Manitoba, Saskatchewan and Alberta. Some communities of Plains Indigenous people lost 75 % or more of their members. It is estimated that more than half of First Nations people living along the Saskatchewan River (territory of the Cree (Nehiyawak), Saluteaux,
Assiniboine, and Blackfoot (Niitsitapi) died of smallpox or epidemic-related starvation. The smallpox epidemic of 1780-1782 brought devastation and over
130,000 dead among the Plains Indians.
In 1838, a second
smallpox epidemic struck the Prairies. The
epidemic began with an infected person aboard an American Fur Company steamship
on the Missouri River. The captain refused to halt or quarantine the ship. The
virus eventually reached Forts Union and McKenzie, in what is now North Dakota
and Montana. In the mid to late nineteenth century,
at a time of increasing European-American travel and settlement in the West, at
least four different epidemics broke out among the Plains tribes between
1837 and 1870.
When
the Plains tribes began to learn of the "white man’s diseases" many
intentionally avoided contact with them and their trade goods. But the lure of
trade goods such sometimes proved too strong. The Indians traded with the white
newcomers anyway and inadvertently spread disease to their villages.
Smallpox
first reached the Pacific Northwest in the late 18th century. In the
late 1770s, the disease killed many members of Tlingit, Haida, Kwakwaka'wakw, Nuu-chah-nulth, Salish
and Ktunaxa communities.
In 1782, roughly two-thirds of the Stó:lō population died after contracting
smallpox. During the
1770s, smallpox killed at least 30% of the West Coast Native Americans.
In 1862, a
person infected with smallpox arrived in Victoria aboard a steamship travelling from San Francisco. The disease
spread to an encampment north of the city, where traders from many First Nations stayed. When the residents of the encampment
left for their homelands, the disease spread across the colonies of Vancouver Island and British Columbia.
The 1862 Pacific Northwest smallpox epidemic, as it was called, devastated the
Indigenous peoples of the Pacific Northwest Coast, with a death rate of over
50% for the entire coast from Puget Sound to Southeast Alaska. In some
areas the native population fell by as much as 90%. The disease had devastating impacts on many peoples, including the
nations of Kwakwa̱ka̱’wakw, Tlingit, Heiltsuk, Haida, Tsimshian, and Tsilhqot'in, as well as some Coast Salish and Interior Salish nations.
Although a variety of infectious diseases existed in the Americas in pre-Columbian times, the limited size of the populations, smaller number of domesticated animals with zoonotic diseases, and limited interactions between those populations, hampered the transmission of communicable diseases. One notable infectious disease of American origin is syphilis. 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, and the consequent Columbian exchange of microorganisms that cause human diseases.