Explain the impact of new diseases on the Americans

Contact between Europeans and Native Americans led to a demographic disaster of unprecedented proportions. Many of the epidemic diseases that were well established in the Old World were absent from the Americas before the arrival of Christopher Columbus in 1492. The catastrophic epidemics that accompanied the European conquest of the New World decimated the indigenous population of the Americas. Influenza, smallpox, measles, and typhus fever were among the first European diseases imported to the Americas. During the first hundred years of contact with Europeans, Native Americans were trapped in a virtual web of new diseases. European diseases, seeds, weeds, and animals irreversibly transformed the original biological and social landscape of the Americas. By 1518, the Native American demographic catastrophe and the demands of Spanish settlers for labor led to the importation of slaves from Africa. Thus, the Americas quickly became the site of the mixing of the peoples and infectious agents of previously separate continents