I think the great Cecile may have already addressed this,if so please feel free to mock me for my sloth since I’m not bothering to look for it. It is often stated that Native Americans were devistated by diseases brought over by Europeans. Did any “New World” diseases effect the Europeans, and if so, did any end up in Europe?
Great pox, AKA syphillus, came from the new world and cut quite a swath through europe when the explorers broughtit home with them.
Diseases did spread east, as mentioned, but they weren’t nearly as devastating as the ones Europeans brought here. For a very thorough explanation why, read “Guns, Germs, and Steel”, by an author whose name I’ve forgotten at the moment. Long story short, Europeans had a lot more domesticated animals than Native Americans, so were exposed to many germs for generations, resulting in immunity to many diseases. The Native Americans, lacking these animals, were never exposed to the germs and so were devastated. So when they met, the Europeans were carrying more germs the Americans hadn’t seen than the Americans were carrying that the Europeans hadn’t seen. And the Europeans probably had better immune systems in general.
Cecil did cover this, and please do check in the archives if you suspect he did.
A previous thread on the same subject: http://boards.straightdope.com/sdmb/showthread.php?threadid=26984
Some speculate that Yellow Fever also originated in the New World and spread to Africa and Southern Europe. Others believe it started in Africa and spread to the New World. The Encyclopedia Britannica says the first recorded outbreak was in South America.