The plague

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The plague

  1. 1. The plague: Yersinia pestis Laura Brennan, Hayley Gibbins, Kirsty Heath, and Sabrina Ul-Hasan http://www.sciencephoto.com/media/11356/enlarge
  2. 2. <ul><li>“ Ring Around The Rosy </li></ul><ul><li>A Pocket Full Of Posies </li></ul><ul><li>Ashes, Ashes </li></ul><ul><li>All Fall Down” </li></ul>It is thought that this nursery rhyme has origins from plague. “Ring” refers to an early clinical sign that appears on the skin (perhaps the ulcer that commonly appears around a flea bite wound infected with Y. pestis ); “a pocket full of posies” refers to the use of flower petals as a means of warding off the stench and infection of a plague victim; “ashes, ashes” refers to dust to dust; and “all fall down” refers to victims who were falling down dead.
  3. 3. Yersinia pestis- The Anatomy <ul><li>Yersinia originally classified in Pasteurellaceae family </li></ul><ul><li>Based on DNA similarities with E.coli, Y.pestis is now part of Enterobacteriaceae family </li></ul><ul><li>11 named species in genus: 3 are human pathogen; </li></ul><ul><li>Y.Pestis, Y.pseudotuberculosis, Y.enterocolitica </li></ul><ul><li>Y.pestis and Y.pseudotuberculosis rarely infect humans </li></ul><ul><li>-Y.enterocolitica is the cause of 1-3% of diarrhea cases caused by bacteria </li></ul>
  4. 4. Yersinia pestis-The Anatomy <ul><li>Gram-negative </li></ul><ul><li>Pleomorphic coccobacillus </li></ul><ul><li>Aerobic, facultatively anaerobic, facultatively intracellular </li></ul><ul><li>3 biovars: Antiqua, Medievalis, and Orientalis </li></ul><ul><li>Yersinia pestis has multiple plasmids (110 and 9.5 kbp plasmids) and virulence factors (F1, Murine exotoxin, LPS endotoxin, coagulase, pesticin, plasminogen activator). </li></ul>
  5. 5. Transmisson <ul><li>In addition to the common Yersinia virulence plasmid pCD~70-kb ,Y.pestis harbours 2 unique plasmids regulting its transmission:the murine toxin (pMT1 ~100-kb) and plasminogen activator/ ‘pesticin’ (pPCP ~9.6kb) plamids </li></ul><ul><li>Plasmids carry ‘molecular fingerprints’ left behind during evolution and account for emergence of Y.Pestis </li></ul><ul><li>The DNA relationship between Y. pestis and Y. </li></ul><ul><li>pseudotuberculosis chromosomes is greater than eighty percent as measured by DNA::DNA hybridization analysis </li></ul>
  6. 6. Plasmids
  7. 7. History-The Arrival <ul><li>Arrived in October 1347 </li></ul><ul><li>Started in Asia then travelled to Europe by rat infested Italian ships trading goods across the Mediterranean sea </li></ul>
  8. 8. Geographical spread
  9. 9. Types of plague <ul><li>Bubonic plague </li></ul><ul><li>Most common </li></ul><ul><li>Infection of lymph system (attacks immune system) </li></ul><ul><li>Bacterium kills by cutting off cells ability to communicate with immune cells that are vital to fight bacterial invasion </li></ul><ul><li>YopJ the protein Yersinia uses to block this signalling process is one of 6 proteins injected into macrophages </li></ul><ul><li>Pneumonic plague </li></ul><ul><li>-Most serious type </li></ul><ul><li>-Infection of lungs leading to pneumonia </li></ul><ul><li>Septicemic plague </li></ul><ul><li>-Bacteria reproduces in the blood </li></ul><ul><li>-Can be contracted like bubonic plague but is most often seen as a complication of untreated bubonic or pneumonic plague </li></ul>
  10. 10. Epidemiology-Environment
  11. 11. Epidemiology-vector dynamics
  12. 12. Epidemiology-Host suseptibility

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