USA HISTORY

Detailed explanation-1: -When the Europeans arrived, carrying germs which thrived in dense, semi-urban populations, the indigenous people of the Americas were effectively doomed. They had never experienced smallpox, measles or flu before, and the viruses tore through the continent, killing an estimated 90% of Native Americans.

Detailed explanation-2: -Smallpox was the disease brought by Europeans that was most destructive to the Native Americans, both in terms of morbidity and mortality. The first well-documented smallpox epidemic in the Americas began in Hispaniola in late 1518 and soon spread to Mexico.

Detailed explanation-3: -Many of the diseases, such as syphilis, smallpox, measles, mumps, and bubonic plague, were of European origin, and Native Americans exhibited little immunity because they had no previous exposure to those diseases. This caused greater mortality than would have occurred if these diseases been endemic to the Americas.

Detailed explanation-4: -Diseases such as treponemiasis and tuberculosis were already present in the New World, along with diseases such as tularemia, giardia, rabies, amebic dysentery, hepatitis, herpes, pertussis, and poliomyelitis, although the prevalence of almost all of these was probably low in any given group.