1. Black Death
A Study of the Plague

2. The Darkest Ages Justinian’s Plague Great Pestilence/Black Death
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

3. 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

4. The Cause of The Plague (cont’)
Wayson Stain of Yersinia Pestis

5. The Cause of The Plague (cont’)
Fluorescence antibody positively is seen as bright, intense green staining around the bacterial cell

6. 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.

7. 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.

8. 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.

9. 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.

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

11. 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.

12. 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, % of cases lead to coma and death in about 2-3 days.

13. 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”

14. Plague: Treatment

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

16. Plague: Treatment Gentamycin Aminoglycoside
Preferred drug in certain cases:
Can be used in pregnancy
Safe for infants

17. Plague: Treatment Chloramphenicol Tetracyclines Sulfonamides
Useful only in cases of bubonic/septicaemic plague
Tetracyclines
Sulfonamides
Sulfmethoxazole/trimethoprim safe in infants

18. 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

19. Modern Day Plague