It is well known that the European colonists brought many infectious diseases to the Americas, and that these had a deadly effect on the native populations, because they had no immunity to them. Were there any local infectious diseases to which the colonists were not immune? I’ve never heard of such. I’m not aware that the colonists suffered any epidemics, or that they brought any new and unusual diseases back to Europe.
Why not? Is this merely an accident of history, that there were no infectious diseases in the Americas which did not already exist in Eurasia? Or is there some explanation?