The diseases that brought from Europe by explorers and colonists included smallpox, chickenpox, typhus, malaria, etc, but the only disease I'm aware of that was transferred from the Native Americans to the Europeans was syphilis, and that is debated.
Why was there such an asymmetrical impact of disease on Natives? Shouldn't the Europeans have been similarly impacted by the novel nature of New World diseases?
Hi! While there's always more to say on the subject, you might be interested in some of our previous excellent answers on disease in the Americas, especially the ones from u/anthropology_nerd and /u/400-rabbits on the impact of indigenous American diseases on Europeans.