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The plague

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  • 1. The plague: Yersinia pestis Laura Brennan, Hayley Gibbins, Kirsty Heath, and Sabrina Ul-Hasan http://www.sciencephoto.com/media/11356/enlarge
  • 2.
    • “ Ring Around The Rosy
    • A Pocket Full Of Posies
    • Ashes, Ashes
    • All Fall Down”
    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. Yersinia pestis- The Anatomy
    • Yersinia originally classified in Pasteurellaceae family
    • Based on DNA similarities with E.coli, Y.pestis is now part of Enterobacteriaceae family
    • 11 named species in genus: 3 are human pathogen;
    • Y.Pestis, Y.pseudotuberculosis, Y.enterocolitica
    • Y.pestis and Y.pseudotuberculosis rarely infect humans
    • -Y.enterocolitica is the cause of 1-3% of diarrhea cases caused by bacteria
  • 4. Yersinia pestis-The Anatomy
    • Gram-negative
    • Pleomorphic coccobacillus
    • Aerobic, facultatively anaerobic, facultatively intracellular
    • 3 biovars: Antiqua, Medievalis, and Orientalis
    • Yersinia pestis has multiple plasmids (110 and 9.5 kbp plasmids) and virulence factors (F1, Murine exotoxin, LPS endotoxin, coagulase, pesticin, plasminogen activator).
  • 5. Transmisson
    • 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
    • Plasmids carry ‘molecular fingerprints’ left behind during evolution and account for emergence of Y.Pestis
    • The DNA relationship between Y. pestis and Y.
    • pseudotuberculosis chromosomes is greater than eighty percent as measured by DNA::DNA hybridization analysis
  • 6. Plasmids
  • 7. History-The Arrival
    • Arrived in October 1347
    • Started in Asia then travelled to Europe by rat infested Italian ships trading goods across the Mediterranean sea
  • 8. Geographical spread
  • 9. Types of plague
    • Bubonic plague
    • Most common
    • Infection of lymph system (attacks immune system)
    • Bacterium kills by cutting off cells ability to communicate with immune cells that are vital to fight bacterial invasion
    • YopJ the protein Yersinia uses to block this signalling process is one of 6 proteins injected into macrophages
    • Pneumonic plague
    • -Most serious type
    • -Infection of lungs leading to pneumonia
    • Septicemic plague
    • -Bacteria reproduces in the blood
    • -Can be contracted like bubonic plague but is most often seen as a complication of untreated bubonic or pneumonic plague
  • 10. Epidemiology-Environment
  • 11. Epidemiology-vector dynamics
  • 12. Epidemiology-Host suseptibility