Works Cited

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Yersinia pestis scientific history

The plague bacillus was first isolated in 1894 by Andre Yersin, a French bacteriologist. Although he originally named it Pasteurella pestis after his teacher, the name giving its discoverer credit, Yersinia pestis, is the one that stuck. It was originally placed in the Protista kingdom under the classification of that time, but later moved to the Monera kingdom, which was renamed the Prokaryotae kingdom.

Yersinia pestis scientific classification

The Prokaryotae kingdom contains all bacteria, and its name is derived from the fact that all bacteria are Prokaryotes, that is, single-celled organisms without a nucleus in their cell. The Eubacteria subkingdom contains all bacteria that are not archaebacteria. The Gracilicutes division contains gram-negative bacteria, bacteria that respond negatively to the gram strain test. Proteobacteria are so-called "purple bacteria," and Enterics is a class of disease-causing bacteria. Yersinia is the genus of disease-causing bacteria that are motile only outside of a mammalian host. And Yersinia pestis is the species of bacteria that casues plague.

* A debate sparked in 1990 by American molecular biologist Carl Woese has produced many different ways of classifying organisms. The classification system used was the one found in both of my book sources, which were both published after 1990.

The Black Death and yersinia pestis

No other bacteria, perhaps organism, had so much of an effect on human history as Yersinia pestis, the bacteria that causes plague. Many outbreaks of plague have caused death and population reduction throughout history. The most famous, however, was the notorious Black Death of medeival times that killed one third of the population of 14th century Europe. People watched their family and friends die with sickly buboes (swollen lymph nodes) on their necks and a color near black all over their bodies, caused by respiratory failure. People who contracted the disease and were unable to fight it off died within three to five days.

However it originated (some think from China on the Silk Road), this horrible epidemic caused riots, the displacement and persecution of people, and an increase of wealth throughout Europe. In Germany and Switzerland especially, Jews were falsely accused of and persecuted for having deliberately poisoned the waters with the disease. They were, after all, the only ones who drank well water, not stream water, and were not affected by the plague. People were displaced all over Europe trying to flee the plague. Wealth was also displaced, as the disease killed people, but not their possesions.

The pestilence, or great mortality, as it was also called, influenced art during the period. As expected, most artwork of the time dealt with death and the plague. The painting shown here is on the city of Marseilles, devasted by an outbreak of plague. It was not only the subject of art that was being influenced, but the amount of art being sold. Newly wealthy people erected statues and sculptures in cathedrals as a sign of gratitude of being spared from the plague, or to prevent future infection. Religious practices were also influenced, as Christians of the time believed that disease was a call to repentance. As a result, many joined a once relatively unknown group of flagellants, people who beat and whipped themselves to atone for their and others' sins. Eventually, the practice was banned in most cities, and the flagellants eventually disbanded.

Ironically, ideas about medicine and the treatment of disease were little influenced. An Italian, Girolamo Fracastoro, first explained the theory of contagious disease. However, his theory was that it was only the poor who spread it. Although this theory was eventually discarded, the same medicinal practices used during the Black Death were utilized, at first, during the European Cholera outbreak of the 1830s.