The diseases of the Old World (influenza, diptheria, smallpox, measles, etc) were introduced to the Americas with devastating effects. But were there any diseases brought from the New World to Europe, even if they had lesser impacts?
Not to discourage further discussion, but you may want to check out some of the questions and answers in the FAQ.
To summarize some of the responses linked there, yes, Europeans did get diseases from the Americas. It appears that syphilis spread to Europe from the Americas.