Then what kept neanderthal diseases from wiping US out??
See my post in message #1. :’)
But, again, looking at the effect of European diseases on the New World, while they decimated populations to the point that native cultures were unsustainable, they did not exterminate them. A small number of people possessed natural immunity, just a a small number of Europeans had some type of immunity to the Black Death. I do not see an historical precedent to a disease wiping out an entire race; always some few survive, and later flourish.