The Black Death was a devastating pandemic that peaked in Europe from 1346-1353, killing around 30% of Europe's population or 25 million people. It was caused by the bacterium Yersinia pestis, which was usually transmitted via fleas that lived on rodents like black rats. The disease originated in Asia and spread along trade routes. Symptoms included fever, vomiting of blood, and the appearance of swollen and bloody lymph nodes called buboes. While the Black Death resulted in massive mortality, its spread declined in later centuries as the brown rat population increased and was less susceptible to fleas carrying Y. pestis. Nowadays plague can be treated effectively with antibiotics.

1. The Story of Black Death

2. Background
 Peaking from Europe
 From 1346-1353
 Killed 30% of Europe‟s population
 25 million people

3. Why was the disease called
„‟Black Death‟‟?
 one of the symptoms produced a
blackening of the skin around the
swellings. or buboes
 The buboes were Red->Dark
purple->black
 People was dead with black spot on
their skin.

4. Symtoms in human
 the appearance of buboes (or gavocciolos) in the
groin, the neck and armpits
 Buboes oozed pus and bled when opened
 Red and black spots on their skin
 acute fever and vomiting of blood
 aching limbs and terrible pain
 Most victims(70%) died within 4-7 days after
infection

5. Video about the symtoms
 http://video.google.com/videoplay?doc
id=9213528526753799697

6. Did Black Death happen
again?
 Yes!
 The most recent case was reported in
Oregon, United States in 2010
 They confirmed that Y. pestis caused
the Black Death and later epidemics.
 Black Death is bubonic plague(鼠疫).

7. How Black Death spread?
 Black rat, Rattus rattus
 Oriental rat flea, Xenopsylla cheopis
 Human flea, Pulex irritans
 Yersinia pestis

9. Rats
 Rodents
 Maybe direct diseases carrier
 (including Weil's disease, rat bite
fever, cryptosporidiosis and
hantavirus pulmonary syndrome.)
 The original carrier
for the plague-
infected fleas was
the black rat

10. Black rat, Rattus rattus
 Originated in tropical Asia, then to
Near East
 Spread across the world with
European during trading oversea
 Lives in close proximity to humans
 Certain resistant to the plague
 Die-off enhance the transmission

11. Fleas
 Acquire Y. pestis by feeding an
infected animal
 Flea‟s digestive tract contain certain
protein that is important for survival of
Y. pestis
 Y.pestis aggregate and cause
starvation and regurgitation of blood
 Flea also change its host after
infection

12. Yersinia pestis
 Rod- shaped, Gram- negative and
non-motile bacteria
 Resist phagocytosis and even
reproduce inside phagocytes and kill
them.

13.  Bubonic plague: an enlarged, infected
lymph nodes called buboes
 Septicemic plague: occurs when plague
bacteria multiply in bloodstream
(complication of bubonic plague)
 Pneumonic plague:
Secondary: occur when the bacteria
spread to lungs(complication of bubonic
plague)
Primary: inhale infectious droplets
coughed into the air by a person or animal
with pneumonic plague

15. The end of plague
 Brown rat, Rattus norvegicus
 Yersinia pseudotuberculosis
 Other reasons

16. Brown rat, Rattus norvegicus
 Larger
 Aggressive
 Pushed the smaller and more mouse-like Black
Rat out of buildings, alleys, storage sheds and
sewers and almost totally out of existence in
the whole world.
 Is not the host of oriental rat flea

17. Yersinia pseudotuberculosis
 “less virulent parasite will replace a
more virulent parasite over time” --
Pathology
 Some rats had acquired resistance to
bubonic plague bacteria from
exposure to this pathogen
 Bubonic plague failed to sweep the
continent ever again the way it did in
the mid-fourteenth century

18. Other hypothesis
 Weather: the plague drifted away
when winter began
 Fire: Great London fire killed or drove
away the majority of rats and the
plague left with them
 Extensive control measures against
rats & their fleas

19. Treatment
 Antibiotics (nowadays)

20. Can you believe that the Black
Death can bring some
advantage to human?
 the descendents of the victims of
Black Death will not get AIDS even
they are infected by HIV
 ->due to high level of a gene
mutation
called CCR5-delta 32

21. Conclusion
 Black Death was once deadly and
characterized as the horrible crisis in
the middle ages Europe.
 But now, it will never become our
nightmare again because we have
already investigated all its detail.

22. Reference
 http://findmeacure.com/2008/07/17/plague/
 http://hospital.kingnet.com.tw/essay/essay.html?category=%C2%E5%C3%C4%A
Fe%AFf&pid=5137
 http://baike.baidu.com/view/70725.htm
 http://en.wikipedia.org/wiki/Bubonic_plague
 http://en.wikipedia.org/wiki/Acral_
 http://www.goodhealthtipsonline.com/2011/03/bubonic-plague-history-cause-
symptom.html
 http://boisestate.edu/courses/westciv/plague/
 http://www.dhpe.org/infect/plague.html
 http://www.themiddleages.net/plague.html
 http://www.middle-ages.org.uk/black-death.htm
 http://boisestate.edu/courses/westciv/plague/05.shtml
 http://terriermandotcom.blogspot.com/2004/08/rats-prevent-plague.html
 http://www.ratbehavior.org/WildRatDisease.htm#Plague
 http://science.nationalgeographic.com/science/photos/plague/#/plague-
today_9445_600x450.jpg