BY Grace Gregg The Black Death was the devastating global epidemic of the bubonic plague—named after the swollen lymph nodes, called buboes, where the bacteria Yersinia Pestis begins to multiply. Buboes typically begin to form at the site bacteria first entered the human body (via an infected flea). Yersinia pestis originated in or near China and was transmitted by routes such as the Silk Road which allowed for the spread of pandemics. This bacteria has three existing biovars (variants that differ physiologically in a prokaryotic strain): Antigua, a strain isolated to Africa, Medievalis, a strain isolated in Central Asia, and Orientalis, an unisolated strain that is very widespread. Yersinia pestis is a zoonotic bacteria, which is a disease that can be commonly transmitted from animals to humans. Zoonotic infections are easily emerged or re-emerged by overuse of antimicrobials in medicine, intensified farm settings, and closer interactions with animals which makes them especially dangerous. This bacterium survives through a continuous cycle involving ticks and fleas. Unlike in humans, Yersinia pestis circulates within rodent populations at low rates without causing immoderate death. Due to this low rate circulation, the infected animals and their accompanied fleas become long term reservoirs for the bacteria. This process is known as the enzootic cycle. In some instances, other animal types can become infected and an outbreak among animals occurs: This is called an epizootic. Epizootic cycles are likely in sectors of high density rat populations and are especially dangerous because humans are more at risk during and after the event. Once a host is infected, plague can be transmitted through contact with infected fluids, direct and close contact with someone infected, fleas moving from a host to a healthy human being, and from popped buboes which spread highly infective bubonic fluid to those who have come into contact. The bubonic plague incubates in the human body for 1-6 days and, if left untreated, the bacteria can invade the bloodstream and multiply, causing a severe and fatal version of the plague, septicemic plague. Initial symptoms of the bubonic plague include fever, trembling, weakness, and profuse sweating. As bubonic plague further develops in the body, buboes begin to form in the lymph nodes through the build up of dead blood and pus. If buboes are not cut open, the buildup of blood will cause it to expand in size. The common dilemma for a bubonic plague patient is that if the buboes are cut open, the patient can die from toxic shock, but if the swelling buboes are not lanced, the buildup of blood can cause death. Bubonic plague has a fatality ratio of 30-60 percent if left untreated by antibiotics. The plague causing Black Death (in Europe and Asia during the mid-1300’s) was brought to Europe during October of 1347 after twelve ships, travelling from the Black Sea, arrived at the Sicilian port of Messina. When people arrived at the docks to meet the sailors, it was found that most of the men were dead and the few that were still alive were covered in bloody and pus filled boils. The Sicilian authorities quickly ordered the ships to leave the harbor but by that point, the bubonic plague was already spreading. Normal diseases follow a pattern of selective mortality that occurs from mortality targeting the individuals at a higher risk of death rather than killing everyone at the exact same rate. However, the Black Death did not follow a pattern of selective mortality, it indiscriminately killed everyone in a population causing an especially high rate of death. As the plague spread, there was a widespread death of serfs in medieval Europe because they were most susceptible due to their living systems putting them through closer contact with others, causing the social system of feudalism to break apart. The most hard hit class were the lower class due to peasantry living in unsanitary conditions and being especially malnourished all while the wealthy fled to nearby countryside to avoid infection. One of the groups with the highest mortality rate were Priests, travelling from home to home to bring solace to the infected made them highly vulnerable. The mortality rate for priests during the Black Death was 42-45 percent while the mortality rate of the general population was around 30 percent. The church’s power declined and the destruction of a unified Christian religion occurred, meaning that the Black Death was a large contributor to the Protestant Reformation. The plague that struck Europe had an estimated twenty-five million deaths, which was almost a third of the continent's population during that time period. The sheer amount of fatalities made the social structure of Europe unidentifiable, many flourishing cities became almost completely empty along with fields of crops covered in rot due to no one being alive to harvest them. A sizable cause for this widespread was not just sanitation and overcrowding, but the scientific understanding of how germs behaved. Doctors and scientists of the time believed in the miasma theory, the theory that diseases were caused by miasmas or “bad air”. Miasmas are poisonous discharges from decaying carcasses, rotting plant life or molds. Doctors believed the smells would go into the body and bring about diseases like cholera or chlamydia. This idea is evident in the infamous plague doctor’s mask, the beak mask would hold dried flowers, herbs, and spices so that bad smells could be removed and not infect the physician. Plague doctors' cloaks and hats covered their entire body and were made of oiled Moroccan leather in order to prevent the miasma from entering their bodies through the pores. Many plague doctors of the time had no certified medical training or had limited experience as a physician. The medical practices of these doctors were even more questionable, for they would cover buboes in human feces believing that it would cure their patients when in reality it likely made infection even worse. Many doctors also practiced bloodletting, the practice of drawing blood from a patient through leeches or cuts with the belief that it would cure an ailment. Onions or herbs were rubbed onto boils, some would cut up a pigeon and rub it onto the infected body. Not just doctors , but the European public wholeheartedly believed that drinking vinegar, arsenic, or mercury could also cure them from the plague along with grinding up an emerald and drinking it in wine. Overall, the threat of bubonic plague is very diminished with the introduction of antibiotics, sanitary living conditions, and a better understanding of the human body. Modern scientists believe in the reliable germ theory, the theory that certain diseases are caused by microorganisms invading the body. Today, there are an average of seven cases of bubonic plague in the U.S each year. There is currently a licensed vaccine that is made from Yersinia pestis organisms grown in an artificial medium that is then inactivated with formaldehyde and preserved in .5% phenol. Today, if you get treated for bubonic plague in a timely manner your mortality rate drops by 30-55 percent. References:
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