Black Death

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Black Death

• A Study of the Plague

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The Darkest Ages

• Justinians Plague
• A.D. 541, Egypt
• 70,000 dead within 2 years
• Great Pestilence/Black Death
• 1346, Europe
• 30 million dead
• Most recent pandemic
• 1890, China
• 12.5 million dead

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The Cause of The Plague

• The bacterium which causes plague was first
  isolated
• Time 1894
• Place Hong Kong
• By Andre Yersin, a French bacteriologist
• The bacteria was later named after him, Yersinia
  pestis

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The Cause of The Plague (cont)
Wayson Stain of Yersinia Pestis
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The Cause of The Plague (cont)
Fluorescence antibody positively is seen as
bright, intense green staining around the
bacterial cell
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How is Plague Transmitted?

• Plague is transmitted from animal to animal by
  the bites of infective flea.
• Both male and female fleas can transmite the
  infection
• Plague is also transmitted from animal to human
  in the same way.

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How is Plague Transmitted? (cont)

• Plague is also transmitted by inhaling infected
  droplets expelled by coughing, by a person or
  animal, especially domestic cat
• The organism may enter through a break in the
  skin by direct contact with tissue or body fluids
  of a plague-infected animal.

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How is Plague Transmitted? (cont)
Male Xenopsylla cheopis (oriental rat flea)
engorged with blood. This flea is the primary
vectore of plague epidemics in Asia, Africa, and
South America.
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Yersinia pestis

• Bacteria multiplies, attaches to host cell and
  injects the following proteins
• Invasin A protein that helps it in attachment
  and gain entry to the human cells.
• Plasminogen activator protease prevents the
  fibrin clot to form which would trap the bacteria
  at the site of the flea bite
• YOPS (Yersinia outer-membrane proteins) it is
  injected into human cells, it interferes with
  signaling and prevents phagocytosis by immune
  system cells.

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Types of plague

• Bubonic
• Pneumonic
• Septicemic
• The initial symptoms are headache, nausea,
  aching joints, and a general feeling of ill
  health.

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Bubonic Plague

• Appearance of buboes, painful inflammations about
  the size of chicken eggs at lymph nodes in the
  neck, armpits, and groin.
• Hemorrhaging under the skin, causing black
  splotches
• Late stage symptoms very high fever and
  delirium.
• About 50-60 of the infected die after 4 days
  when left untreated.

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Pneumonic Plague

• When the bacterium enters the lung
• It usually spreads by sneezing
• Symptoms
• Coughing, expulsion of slimy sputum with traces
  of blood
• Free-flowing and bright red sputum appears in
  advance stages.
• Untreated, 95-100 of cases lead to coma and
  death in about 2-3 days.

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Septicemic Plague

• Is when a large amount of the bacterium is found
  in the bloodstream
• Symptoms
• Rashes, gangrene, sudden high fever.
• During the last hours, victims body turns deep
  purple due to respiratory failure
• Victim usually dies the same day. Fatality is
  100. The color that all plague victim have
  before dying is what gave it the name
• Black Death

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Plague Treatment
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Streptomycin

• Drug of choice for treatment of plague
• Bacteriocidal
• Inhibits protein synthesis
• Damages cell membranes
• Aminoglycoside
• contains amino sugars attached to an
  aminocyclitol ring (hexose nucleus) by glycosidic
  bonds

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Plague Treatment

• Gentamycin
• Aminoglycoside
• Preferred drug in certain cases
• Can be used in pregnancy
• Safe for infants

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Plague Treatment

• Chloramphenicol
• Useful only in cases of bubonic/septicaemic
  plague
• Tetracyclines
• Sulfonamides
• Sulfmethoxazole/trimethoprim safe in infants

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Mortality

• Without treatment, plague kills 50-90 of
  infected people
• With treatment, 5-15 will die
• A strain of Yersinia pestis demonstrating
  streptomycin resistance was found in Madagascar,
  1995

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Modern Day Plague