Another really good book is William McNeill's "Plagues and Peoples". It discusses worldwide effects of diseases on populations, not just the Americas, and is v

Another really good book is William McNeill's "Plagues and Peoples". It discusses worldwide effects of diseases on populations, not just the Americas, and is very readable. He also points out that in populations with heavy disease loads, most are exposed as children often developing immunity thereafter, while newly exposed populations lose adults to the disease, which causes greater economic and military debility to the society.