African slaves were used on the sugar plantation of the West Indies, and with them came smallpox. The first of these slaves were brought by Columbus. In 1495, fifty-seven to eighty percent of the native population of Santa Domingo and in 1515, two-thirds of the Indians of Puerto Rico were wiped out by smallpox. Ten years after Cortez arrived in Mexico, the native population had been reduced from twenty-five million to six million five hundred thousand a reduction of seventy-four percent. Even the most conservative estimates place the deaths from smallpox above sixty-five percent (Bray).
Prior to the arrival of Europeans, various sources estimate native population in North and South America at ninety to one hundred million. In the fifteen hundreds, the American Indian population in North America has been estimated at approximately twelve million, but by the early nineteen hundreds, the population had been reduced to roughly four hundred and seventy-four thousand. It is impossible to arrive at a number for the millions of American Indians killed during this period by European diseases with smallpox the deadliest by far.
Smallpox reached what was to become the United States either from Canada or the West Indies. The first major outbreak of an infectious disease recorded on the northeastern Atlantic coast was 1616-19. The Massachusetts and other Algonquin tribes in the area were reduced from an estimated thirty thousand to three hundred (Bray). When the Pilgrims landed a year later in 1620, there was few Indians left to greet them. Many observers believe this infectious disease was smallpox.
By the end of the sixteen hundreds, smallpox had spread up and down the eastern seaboard and as far west as the Great Lakes. Stearn and Stearn estimated there were approximately one million one hundred and fifty thousand Indians living north of the Rio Grande in the early sixteenth-century, but by 1907, there were less than four hundred thousand (Bray). This decline was not due to smallpox alone. Other diseases played a role, as did intertribal warfare and conflicts with the United States.
It was inevitable that when Europeans came to America that European diseases were going to run rampant through the indigenous populations of the Americas. The native populations of North and South America had no immunities, or genetic tolerance, to any of the European diseases, and not all white Americans had immunities to them either. It is commonly believed that syphilis spread from Native Americans to Europeans. There is developing DNA evidence that suggests syphilis (Yaws) was in Europe prior to Columbus's time. Like every other disease there is growing evidence that Europeans brought syphilis to America.
(this link is not meant to debilitate in any way the historic tragedy that decimated the indigenous population of the New World, but to further note--as some have suggested--that diseased blankets were circulated intentionally by Europeans because Indians were "in the way".)--lwc