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Yersinia species. Yersinia pestis Yersinia enterocolytica Yersinia pseudotuberculosis. Plague mortality. Plague has claimed millions of lives: 6th century - killed 100 million 14th century - killed 25 million (1/4 of Europe) 1890s - killed 10 million (Asia). Yersinia pestis : history.

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yersinia species
Yersinia species
  • Yersinia pestis
  • Yersinia enterocolytica
  • Yersinia pseudotuberculosis
plague mortality
Plague mortality
  • Plague has claimed millions of lives:
    • 6th century - killed 100 million
    • 14th century - killed 25 million (1/4 of Europe)
    • 1890s - killed 10 million (Asia)
yersinia pestis history
Yersinia pestis: history
  • Dr. Yersina identified the causative agent of plague in 1894
  • Only sylvatic cases (~400) of plague have been reported in the south-western US
morphology physiology
Morphology/Physiology
  • Facultative intracellular parasites

Gram-negative, pleomorphic bacillus

Facultative anaerobe

Optimal growth at 28o C

cell cycle
Cell Cycle
  • Mass of plaque bacteria forms in gut of infected flea
  • Flea regurgitates uncapsulated organisms into bite on animal or human
  • Most organisms destroyed by PMN, but some entering histiocytes survive
  • Bacteria re-encapsulate and grow.
  • Progeny is resistant to intracellular killing byPMN
symptoms
Symptoms
  • Draining lymph nodes to become hot, swollen, hemorrhagic and painful (buboes)
  • continued release of organisms causes septicemia and invasion of lungs (pneumonia)
  • Circulating organisms cause subcutaneous hemorrhage (Black Death)
  • Exhaled organisms infect others and cause (pneumonic plague)
the different forms of plague
The different forms of plague
  • Sylvatic
    • In animals (rodents, rabbits, carnivores) only
  • Bubonic
    • Flea (bite) to humans
  • Pneumonic
    • Human (aerosol) to human
bubonic vs pneumonic plague

Bubonic

Pneumonic

Bubonic vs pneumonic plague

entry

flea-bite

inhalation

disease

buboes, hemorrhage, pneumonia

rapid pneumonia

flea & exhalation

exhaled droplets

exit

virulence determinants
Virulence Determinants
  • Calcium dependence at 37o C (lcr)
  • Proteins V & W
  • Yops
  • Envelope (F-1) antigen
  • Coagulase and Fibrinogen Activator (fibrinolysin)
v and w antigens
V and W antigens
  • Plasmid encoded proteins
  • Part of the low calcium (lcr) regulated response
  • Rapid proliferation leading to overwhelming septicemia
yersinia outer proteins yops
Yersinia Outer Proteins (Yops)
  • Plasmid encoded lcr controlled proteins (11)
  • Cytotoxic
  • Inhibit phagocyte migration, engulfment and intracellular killing
  • Inhibit platelet aggregation
f 1 antigen
F-1 Antigen
  • Protein-polysaccharide complex
  • Highly expressed in the mammalian host
  • Not expressed in flea host
  • Antiphagocytic
  • Antibodies to F-1 are protective
coagulase and fibrinolysin
Coagulase and Fibrinolysin
  • Plasmid encoded proteins
  • Coagulase causes clotting and microthrombi formation
  • Fibrinolysin promotes dissemination
diagnosis
Diagnosis
  • Examination of Buboes aspirate stained smears for bipolar staining
  • Fluorescent-antibody
  • Culture/identify organisms (hazardous)
treatment and prevention
Treatment and Prevention
  • Streptomycin or tetracycline
  • Hospitalization and strict isolation
  • Minimize domestic rat population
  • Control flea population