Populations and introduced diseases?

It is often taught in school and other places that the Europeans (Spaniards as the main example) brought diseases to the new world, and that these diseases (smallpox as the most common example, but also others including various STDs) did far more damage than these Europeans ever could have to the native populations.

I find it odd though, that it was such a one sided relationship, that there is never any mention of the reverse effect. One would think that two population groups in relatively perfect isolation for thousands of years would develop immunities/resistances to much different types of pathogens. Therefore once coming in contact with one another, they would have a relatively equal effect in terms of devastation on each other. But at least from what I've learned from history classes this is not the case, and it seems from what is taught in schools that only the native populations were effected by introduced diseases, and that the European settlers never experienced any ill-effects.

I've heard of Montezuma's Revenge, but that seems more of like a symptom than a disease (maybe I'm wrong). But even If Montezuma's Revenge is a disease, it's still fairly localized, and doesn't come close to the devastation that the native populations felt during the initial couple hundred years of European colonization.

So, theoretically, I assume that when two isolated populations come in contact with one another they will equally share the burden of the other's diseases. Thus, my questions are: Are there example of diseases that affected Europeans, but not so much (if at all) the Natives? If so, why would such diseases or epidemics be so little known? Is it a case of the victors writing History?