The Columbian Exchange refers to a historical period of exchange of animals, plants, diseases and technologies between the Old World (Europe, Asia and Africa) and the New World (Americas). . It is considered one of the most important events in cultural history because it affected almost every society by bringing deadly diseases and expanding the variety of new crops and livestock. Today, rats can be found all over the world, but they originated in Asia (usually found in large numbers in China, Japan, and India) and eventually reached Europe via established trade routes , passing through Turkestan and a region around the Black Sea. . Initially, Europeans resented the presence of rats because they helped spread the bubonic plague, which killed a third of the population of Western Europe. Although fleas were the main cause of the spread of bubonic plague, they fed on the blood of infected rats. Other than that, rats don't seem to cause much damage in Europe. While some people view rats as affectionate and intelligent rodents, others may view them as dirty and unattractive. During the period 1450-1750, rats were pests by spreading and eating all the colonists' food, thus competing with the small native animals of the New World. Today, Americans have developed methods to prevent the presence of rats using methods such as poison or traps. However, although rats had a negative impact on the New World by bringing diseases, diseases had always been widespread even before rats became widespread across the world. Rats were transported from the Old World to the New World during the Columbian Exchange across the Atlantic. waters. Although Europe is in the middle of the paper, with unpleasant things, like diseases and dirt. The black rat and brown rat are the most common rat variants found today, but they are now native, through trade, to almost every part of the world. indians/essays/columbian-exchange http://public.gettysburg.edu/~tshannon/hist106web/site19/ http://www.crf-usa.org/bill-of-rights-in-action/bria-25- 1-the Colombian-exchange http://www.jstor.org/discover/10.2307/3868189?uid=3739832&uid=2&uid=4&uid=3739256&sid=21102935431757 http://books.google.com/books?id=7yClMF7IQt8C&pg= PA97&lpg=PA97&dq=how+rats+involved+in+the+Colombian+exchange&source=bl&ots=WYP-eGyHWv&sig=bPGAqL7e-F8cOrV8zX81G2yJ1U0&hl=en&sa=X&ei=HFuIUpbmNanPsASl74DgAQ&ved=0CDQQ6AEw AQ#v=onepage&q=comment%20were%20rats%20involved % 20in%20le%20columbian%20exchange&f=false