Disease

Diseases took an incredible toll on human life in early North America in part because people from three continents came together carrying and introducing diseases indigenous to their own societies. Native Americans suffered the worst, and their mortality tragically was higher than perhaps any in human history. When they initially encountered such common European diseases as smallpox, measles, and dysentery, millions died. In extreme cases 90 percent of some Indian groups perished as entire villages were destroyed. In their sexual interaction with Indians, Europeans sometimes contracted a new disease, syphilis (or at least a strain previously unknown to them), and spread it throughout Europe. Most immigrants to the New World experienced a dangerous “seasoning” period during which they likely would catch various new diseases. Africans also endured a seasoning process that cost many lives. In addition, they introduced various tropical diseases like yellow EEver and malaria to the New World.

The best estimates are that more than 400,000 Native Americans lived in the territory east of the Appalachian Mountains by 1600, including about 105,000 Indians in New England, 150,000 in the Mid-Atlantic region, and 150,000 in the Southeast. The arrival of English and Dutch colonists caused a very sudden and dramatic rise in the death rate among Natives due to “virgin-soil” epidemics (outbreaks of disease to which a population has had no previous exposure) of plague, smallpox, chicken pox, mumps, measles, and influenza. The initial exposure of indigenous peoples to these deadly viral diseases often afflicted nearly all of the population. From 1616 to 1619 a mysterious plague, probably either bubonic or pneumonic, contracted from Europeans sailing along the coast of Maine killed perhaps 90 percent of the seacoast Algonquins. The Great Lakes Native inhabitants, including the Huron, Iroquois, and Mohawk, experienced an epidemic of smallpox that killed at least 50 percent of the inhabitants during the 1630s and 1640s. In 1759 an epidemic of smallpox killed half the Cherokee and Catawba. The Native populations were often so destabilized by these virgin-soil epidemics that their losses occasionally reached 90 percent or higher.

The virulence of European epidemics in combination with the physical aggressiveness of the settlers eventually depopulated most of the eastern seaboard region of its Native inhabitants as they either died or moved westward. Virginia’s Indian people declined so rapidly in the nine decades after the colony was established that only about 1,800 survived in 1700. The Native population of New England fell to about 10,000 by 1675 and only a few hundred by 1750. This depopulation proceeded so rapidly that Natives likely were a minority east of the Appalachians during the late 1680s, and by the 1760s only 150,000 Indians lived east of the Mississippi River.

Virginia was deadly for early colonists as well. During the initial two decades of English settlement, mortality was incredibly high. Conditions on board European ships included the absence of sanitary equipment, overcrowding, insufficient food and medicine, and passengers with contagious diseases, all of which caused colonists to arrive in such a poor state of health that they fell easy victims to typhoid, typhus, and chronic dysentery. Because of their long voyage and poor living conditions in the early settlements, colonists sometimes suffered from scurvy, caused by severe prolonged dietary deprivation of vitamin C. With the advent of long sea voyages, scurvy ranked first among the causes of disability and mortality among sailors. Even on land, scurvy sometimes occurred in early America.

Jamestown and the surrounding communities were ideal sites to maximize the transmission of human pathogens. These early settlements were along a section of the James River where tides carried and mixed saltwater with the freshwater flowing down the river. In the summer, when the river current slowed, the salt tide reached its maximum extent inland and created water levels containing six times the salinity present in normal freshwater. Additionally, the opposing forces of the current from the stream and the tide produced a large stretch of river that was virtually stagnant and polluted with human waste that entered the water by runoff from the shore. The result was that every summer an environment was produced in which typhus and dysentery flourished. The vulnerability of the settlers was particularly high because of their weakened state from insufficient food, the location of their settlements on the riverbank, and their use of the James River rather than wells as their main source of drinking water. Between 1618 and 1624 as many as two-thirds of the deaths of colonists resulted from disease. The diseases declined only as the English moved inland, where wells provided drinking water and they could obtain healthier freshwater from the James River.

Malaria, introduced after 1650, became the Chesapeake’s most virulent pathogen. Slaves carrying the most lethal variants of malaria came from Africa to the New World, and mosquitoes spread it to the European and Native American population. Once established, malaria was impossible to eradicate without draining the mosquito-infested swamps, although colonists were unaware of the mode of transmission of the disease in any case. Malaria profoundly affected public health in the southern tidewater region, and it was a primary reason colonists in the Chesapeake Bay region lived shorter lives than did New Englanders. Malaria also encouraged wealthy white people to live in Charleston during the unhealthy summers, leaving their rice plantations to be run by overseers. The disease rarely killed its victims directly because American settlers used cinchona bark, which contained quinine to limit the ravages of the disease. Still, it weakened the immunity of its victims, who faced recurring bouts of fever, and minor infections sometimes proved fatal in chronic malaria sufferers. Indeed, for every direct malaria fatality, five died of its indirect effects. Pregnant women and new mothers were particularly vulnerable to the disease. The movement inland of southern populations decreased the impact of malaria because the disease is limited to swampy or marshy areas where mosquitoes breed. Therefore, the disease existed almost entirely in the southern tidewater (although it also afflicted a few northern locations). As colonists moved into the Piedmont, the population at risk for acquiring malaria declined.

The rapid increase in slaves in the region in the early 18th century also limited malaria-induced deaths. People of African descent, although not immune to the disease, tolerated attacks better and enjoyed a higher survival rate than did whites. This is partly because many of them carry a single mutation in their hemoglobin gene that results in the production of hemoglobin S instead of hemoglobin A. Individuals who carry the S mutation from one parent and the hemoglobin A gene from the other parent are carriers of the sickle-cell trait. When an individual has hemoglobin S genes from both parents, they have sickle-cell disease. In areas where malaria is endemic, individuals with the sickle-cell trait have a significant advantage because it confers significant resistance to malarial infection, which is less able to attack the red blood cells that contain the altered form of hemoglobin. However, this advantage comes with a high price. If both parents carry the sickle-cell trait, 25 percent of their children will have sickle-cell disease, which is devastating.

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Most Euro-American colonists outside the tidewater South enjoyed longer, healthier lives than their European contemporaries because of the generally benign disease environment. Euro-Americans suffered from fewer diseases because the low population density reduced the transmission of fatal illnesses among individuals. The winter season, when people were weakest because of the lack of fresh food, was safer because a poor transportation system limited transmission of diseases. Other months generally gave the typical family a better source of nutrients to help ward off sickness and to recover from infectious disease.

Most public health crises occurred in cities, where only a fraction of the population lived. Between 1638 and 1763 more than half the major smallpox outbreaks happened in urban communities; 38 percent occurred in the four largest colonial cities of Charleston, Boston, New York City, and Philadelphia. Yellow fever was almost exclusively limited to port cities. The most serious epidemics in the countryside were outbreaks of diphtheria. However, by 1730 in the more densely populated regions of New England and the Delaware Valley, the spread of infectious disease through agricultural regions increased significantly. These regions were struck especially hard during wars, when soldiers were exposed to various diseases while on a campaign, and, returning home, they sometimes spread them to their families and neighbors.

Smallpox (or variola) was the most dangerous disease in North America and eventually became endemic in the major cities. It is a highly communicable febrile viral disease characterized by three or four days of high fevers and rapid pulse followed by the development of widely disseminated vascular, then pustular, skin eruptions. Smallpox is usually transmitted from person to person, but the virus may contaminate clothing, bedding, dust, or inanimate objects and remain infectious for months. Exposure to the disease resulted in almost universal contagion among people who had never been previously exposed to the disease. The occurrence of a large-scale epidemic usually resulted from the absence of the disease from a population for a significant time; when smallpox returned, most inhabitants had no natural defense against the virus. European migrants carried smallpox to the colonies. Indeed, outbreaks of smallpox onboard ships were so common that seaports sometimes mandated that passengers be quarantined before being allowed to land in the city.