The New World of the Western Hemisphere was devastated by the 1775–1782 North American smallpox epidemic. Estimates based on remnant settlements say at least 130,000 people were estimated to have died in the epidemic that started in 1775.
Background
Smallpox was a dangerous disease caused by the variola major virus. The most common type of smallpox, ordinary, historically has devastated populations with a 30% death rate. The smallpox virus is transmittable through bodily fluids and materials contaminated with infected materials. Generally, face-to-face contact is required for an individual to contract smallpox as a result of an interaction with another human. Unlike some viruses, humans are the only carriers of variola major. This limits the chances of the virus being unknowingly spread through contact with insect or other animal populations. Persons infected with smallpox are infectious to others for about 24 days after their infection time. However, there is a period of time in which individuals are contagious but have only begun to experience minor symptoms such as fever, headaches, body aches, and sometimes vomiting.
This epidemic occurred during the years of the American Revolutionary War. During this time, there was no medical technology widely available to protect soldiers from outbreaks in crowded and unhygienic troop camps. Thus, this virus posed a major threat to the success of the Continental Army, led by George Washington.
It is not known where the outbreak began, but the epidemic was not limited to the colonies on the Eastern seaboard, nor to the areas ravaged by hostilities. The outbreak spread throughout the North American continent. In 1775 it was already raging through British-occupied Boston and among the Continental Army's invasion of Canada. During Washington's siege of Boston the disease broke out among both Continental and British camps. Many escaped slaves who had fled to the British lines in the South likewise contracted smallpox and died. In the South, it reached Texas, and from 1778 to 1779, New Orleans was especially hard hit due to its densely populated urban area. By 1779 the disease had spread to Mexico and would cause the deaths of tens of thousands. At its end the epidemic had crossed the Great Plains, reaching as far west as the Pacific coast, as far north as Alaska and as far south as Mexico, infecting virtually every part of the continent.
The pandemic also took a massive toll on the indigenous population of the Americas. The disease was likely spread via the travels of the Shoshone Indian tribes. Beginning in 1780 it reached the Pueblos of the territory comprising present day New Mexico. It also showed up in the interior trading posts of the Hudson's Bay Company in 1782. It affected nearly every tribe on the continent, including the northwestern coast. It is estimated to have killed nearly 11,000 Native Americans in the Western area of present-day Washington, reducing the population from 37,000 to 26,000 in just seven years.
Quarantine methods
Though there was not too much known about viruses and their transitions, English colonists in North America recognized the effectiveness of isolating individuals infected with smallpox. The English colonies were more aware of the features of smallpox than of almost any other infectious disease. It was widely recognized that there were only two options for protecting oneself against this disease, quarantine or inoculation against the disease. Many feared inoculation, and instead chose isolation via quarantine. Individuals with recognized infections were sent to remote locations where they could let the disease run its course without the fear of infecting others. If needed, the scale of the quarantine could be increased. This meant cutting off entire towns from the rest of the colonies for the duration of the disease.