All throughout the Americas, natives suffered from debilitating diseases brought from the old world. I recently read an estimate (who knows how accurate) that up to 80% of the population of the Americas died after being exposed to Europeans. Since the Europeans also would not have an immunity to diseases that existed in the Americas, why didn't they suffer? Are there environmental or socio-political reasons for this?
Well, the short answer is that they did. A ton of colonists died from tropical diseases that they were not used to. They even had a term for the first year or so when a colonist would almost certainly get sick and probably die; "Seasoning." Furthermore, there's pretty good evidence that syphilis, which devastated the European population for centuries, originated in the New World. There's a really good book by Vincent Brown called The Reapers' Garden which is an excellent look at the impact of frequent death on colonial Jamaica.