The bubonic plague is not a virus but rather a bacteria called Yersinia pestis (discovered in 1894 by a bacteriologist named Alexandre Yersin) which lives in the blood of rats as an infection without consequence. It is transmitted from rat to rat by fleas, which we now know were the first carriers of the plague. When a flea bites an infected rat and picks up the bacteria, it quickly reproduces in the flea's digestive tract, causing a mass that does not allow the flea to swallow. The flea begins to starve due to this blockage and bites new rats in hopes of finding food, unable to swallow the flea which vomits what it has bitten into the bloodstream, along with the bacteria which were in the flea's stomach, thus infecting a new rat. rat. The plague began when fleas frantically searching for food began biting humans as well as rats, giving humans Yersinia pestis, which, unbeknownst to the human immune system, manifested itself as the plague (Damen 2014 ). However, humans can not only contract the disease from flea bites, but also by inhaling the bacteria. In humans, the disease can manifest in three ways: bubonic, septicemic or pneumonic. In bubonic plague (which was most common during the Black Death), lymph nodes in the neck, armpits, and groin swell and turn black into "buboes" which then infect the rest of the body. The common practice was to burst these boils, and so usually the infection killed the patient if the disease failed to do so. In septicemic plague, the bacteria inhibits the body's ability to clot, causing internal bleeding that kills the patient. In the case of pneumonic plague, the bacteria takes up residence in the victim's lungs and, within four to five days, the lungs liquefy, killing the patient. With pneumonia... middle of paper ... Jews went viral. " Jspace.com. Np, March 28, 2013. Web. February 10, 2014. "The Black Death: The Horseman of the Apocalypse in the Fourteenth Century." The Black Death. Np, nd Web. February 8, 2014. "The Black Death ." Wordpress.com. Np, December 11, 2008. Web. February 8, 2014. Trueman, Chris. "The Black Death 1348-1350." HistoryLearningSite.co.uk. History Learning Site, nd Web. February 9, 2014. VanPutte, Cinnamon L., Jennifer L. Regan and Andrew F. Russo "Chapter 11: Blood." Seeley's Essentials of Anatomy and Physiology. New York: McGraw-Hill, 2013. N. pag. .Wein, Berel. “The Black Death.” Np, and Web. “What is Hemophilia?” National Heart and Lung Institute. and Blood, July 31, 2013. Web February 10, 2014. Wilensky, Gabriel. “Blame the Jews for the Black Death.”. 2014.