When the Europeans travelled to the New World and brought the diseases that wiped out so many Native Americans, why didn’t the local diseases have the same impact on them?

Question

Were the endemic diseases just less severe?

In: Other

Answer 1

The Americas didn’t have that many endemic infectious diseases. There just wasn’t the factors that led to their development, the Old World was full of dense cities, connected by long trade routes, the domestication of animals took a hold of the Old World and many infectious originally came from this relationship (zoonotic diseases), and there just were more people for diseases to thrive and adapt. Meanwhile the New World was fairly disconnected, animal husbandry was a lot less common than in the Old World and the population was much smaller. 

Syphilis is thought to have existed in pre-contact America. And there’s some studies that show tuberculosis was also present due to seal hunting. But overall, the conditions to develop infectious diseases capable of causing epidemics weren’t there.