Manifest Contagion: Native Americans as Plague Victims & Keystone Species

Hi Omni,A very sad, interesting story. But there's something I can't figure out.If America and Europe were so isolated in their immune defenses, why was the transfer of disease one way--from Europeans to Native Americans, and not in the opposite direction as well?I mean, I'm sure we can come up with plausible explanations. I'm wondering if there's a plausible explanation that has evidence backing it up.It's curious. America should have been filled with new diseases. The Europeans simply brought a small subset of their culture and habitat; America was ENTIRE cultures and habitats.Ben