Bubonic Plague Essay Research Paper Bubonic Plague

Bubonic Plague Essay, Research Paper

Bubonic Plague is an infectious disease of animals and humans caused by a bacterium named Yersinia pestis. People usually get plague from the bite of a rodent flea that is carrying the plague bacterium or by handling an infected animal. Millions of people in Europe died from plague in the Middle Ages, when flea-infested rats inhabited human homes and places of work. Today, modern antibiotics are effective against the plague, but if an infected person does not seek treatment promptly, the disease is likely to cause illness or death. Despite its epidemic history and the deaths of millions of people, the public still knows little about the disease.

Due to its bacterial nature, Yersinia pestis has proven difficult to classify; however, new technologies have allowed researchers to classify it more accurately in the past several years. Y. pestis is a prokaryotic bacterium and, therefore, is of the kingdom Monera. Taxonomists formerly classified its genus, Yersinia, in the family Pasteurellaceae, but based on DNA similarities to Escherichia coli, the Yersinia group became members of the Enterobacteriaceae family. Numerous biochemical differences among its members are the basis of differentiation among the members of the family Enterobacteriaceae. More recently, biologists have applied nucleic acid techniques to assist in the definition of genera and species within this family; hence, as more techniques are applied, newly defined genetic relationships have lead to changes in classification. Though there are 11 named species in the genus Yersinia, doctors consider only three significant human pathogens: Y. pestis, the agent of plague, Y. pseudotuberculosis, and Y. enterocolitica. Y. pseudotuberculosis is the closest genetic relative to Y. pestis but can be distinguished from the plague bacteria by its clinical manifestations and by laboratory test results. Both Y. pestis and Y. pseudotuberculosis do not frequently infect humans in contrast to Y. enterocolitica, which scientists find more frequently in clinical specimens.

The history of bubonic plague is remarkable. For centuries, plague represented certain death for many people living in Asia, Africa and Europe, where, it has been said, populations were so affected that sometimes there were not enough people left alive to bury the dead. Because the cause of plague was unknown, plague outbreaks contributed to massive panic in cities and countries where it appeared. The people believed that the displeasure of the gods or a heavenly disturbance was the cause of the disease. In response, some Christians, known as flagellants, began to beat themselves ritually as penance for their own and for others sins. The public blamed innocent groups of people for spreading the plague and persecuted them for doing so. Numerous references in art, literature, and monuments attest to the horrors and devastation of past plague epidemics. So imprinted in our minds is the fear of plague that, even now, in the 21st century, a suspected plague outbreak can incite mass panic and bring much of the world’s economy to a temporary standstill. The number of human plague infections is low when compared to diseases caused by other agents, yet plague invokes an intense, irrational fear, disproportionate to its transmission potential in the antibiotic/vaccination era.

Several research scientists have proven key in identifying the plague agent and in determining how it is spread. In 1894, the individual research of Yersin and Kitasato in Hong Kong on the discovery of the infectious agent of plague opened the way for others research on the disease and on how it spreads. Kitasato and Yersin described, within days of each other s findings, the presence of bipolar staining organisms in the swollen lymph node (bubo), blood, lungs, liver, and spleen of dead patients. Though both investigators reported their findings, there were a series of confusing and contradictory statements by Kitasato that eventually led to the acceptance of Yersin as the primary discoverer of the organism now named after him, Yersinia pestis. Yersin recorded that the plague affected rats not only during plague epidemics but also preceding such epidemics in humans. In fact, plague was designated, in local languages, as a disease of the rats: villagers in China, India, and Formosa (currently Taiwan) claimed that when hundreds and thousands of rats lie dead in and out of houses, plague outbreaks in people soon followed. Simond described the transmission of plague was in 1898. He noted that persons who became ill did not have to be in close contact with each other to acquire the disease. Numerous observations led Simond to suspect that the flea might be an intermediary factor in the transmission of plague since people acquired plague only if they were in contact with recently dead rats and were not affected if they touched rats that were dead for more than 24 hours. He demonstrated that the rat flea (Xenopsylla cheopis) transmitted the disease from one rat to another and hypothesized that it could do likewise between rats and humans.

The plague is an ancient disease that is not likely to disappear; its continued outbreaks throughout the world attest to its persistent presence. Plague cycles naturally, circulating between small mammals and fleas without human involvement. These periods, during which people report few or no human cases, may l