Evolution of Plague Bacteria

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Sarah Burns
Evolution of Plague Bacteria
The Bubonic Plague otherwise known as the Black Death, has gotten most of its attention from medieval paintings, poetry, and journals of revulsion. The real horror, was the disturbing biological evidence of the bacteria that caused all the pandemics, known as Yersinia pestis. The pathogen got its name from the two investigators Yersin and Kitasato. In 1894, Yersin was known as the main investigator (ergo. Named after him), he claimed that the mice/rats were affected by the plague even before man was affected. Myths and sayings that originated in China, India, and Formosa said that it was the “disease of the rats”. It was Simond who observed that coming into contact with the dead rodents after 24 hours did not transmit the plague to the handler. He hypothesized that it must be in the fleas. He experimented with a plagued rat and a healthy rat, but made sure they never made contact but were relatively in the same vicinity. Not long after the plagued rat was killed, did the healthy rat get infected by the plague and die also(Schoenstadt,2). The bacteria originated from a more previous strain of Yersinia known as, Yersinia pseudotuberculosis. Pseudotuberculosis originated from Yersinia enterocolitica (Wren). How plague was introduced to man had been lacking evidence for many years, and debates submerged that Yersinia pestis was not the bacteria that caused plague but through sequences and varying tests on fossils from medieval graves in London showed that it was indeed Yersinia pestis and not its ancestor Yersinia pseudotuberculosis. The adaptations that this pathogen have acquired were different from that of it’s ancestor’s because it is transmitted through infected flea or rodent bites. Since Y. pestis is a strain of bacillus bacteria, it attaches to a host to thrive and sustain nutrition. Specifically Iron is needed to keep alive the pathogen which is why homo sapiens were the most reliable source to inhabit. Humans need...
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