The thing that bothers me is that everything suggests that a great number of Europeans 'discovered' America before Columbus. Were Spaniards peculiarly infected with disease? I don't doubt that meeting them killed of millions and millions, but I wonder what happened before!
Yes, actually compared to natives of 'discoverd lands' the Spaniards and every other European explorer were disease vectors, because of livestock-born diseases that were rampant all across Europe, Asia and into northern Africa.
In the Americas, there were no animals suitable for penned-in intensive animal agriculture, so the closest equivalent were the controlled buffalo hunts on the plains....which prior to the introduction of horses and guns required the carefully planned out stampeding of a small herd over a sudden, shallow cliff known as a buffalo drop...where word would be sent out to every tribal group within range to come in and take free meat and hides available.
In the forest regions of the Northeast, 'buffalo runs' were created by burning out narrow tracts of forest that bison, deer and elk...and predators would follow deeper into vulnerable enclosed spaces because their desire for fresh vegetation overruled their better judgement. The usual pattern according to oral histories of Erie, Chippewa, Iroquioan and other tribal nations were that treaties had to be made to allow multinational management of animals...but often, when times were harder, tribes closer to the plains would cull too many bison, leaving little or nothing for those at the end of the buffalo run....the Erie indians who lived along the south shore of Lake Erie at present day - Buffalo, New York, and that would obviously lead to conflict, which would lead to wars and breakdowns in treaties and turn everything into chaos.
Back to the subject though, this kind of hunting..as well as open field and open forest hunting did not put prey species in close, symbiotic relationship with their human predators, and that prevented the influenzas and bacterial diseases from jumping species to humans....therefore, people of the New World weren't weak, they were actually stronger and mostly infectious disease free because of the lack of contagious diseases. But that put them all right in direct risk of death from infectious diseases that outsiders had adapted through by a long process of epidemics and survival of the fittest that were able to fend off diseases.