Transcript Epidemics 2012-3 - MHS

The Black Death: Bubonic Plague!
Roots of Civilization
Bellringer:
What do the following things have in common?
HIV
SARS
Bird Flu
Influenza
Malaria
West Nile Virus
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Origins of The Black Death
Historians believe that the pathogen evolved in
Central Asia and spread to Europe during the
1340s. The total number of deaths worldwide
from this pandemic is estimated at 75 million
people, approximately 25-50 million of these
deaths occurred in Europe.
The Black Death is estimated to have killed 30% to
60% of Europe's population and 30% of the
population of China. It may have reduced the
world's population from an estimated 450 million
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to between 350 and 375 million in 1400.
Silk Road
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Primary Source of The Black Death
• In the Italian city of Siena, Agnolo di Tura wrote:
"They died by the hundreds, both day and
night, and all were thrown in … ditches and
covered with earth. And as soon as those
ditches were filled, more were dug. And I,
Agnolo di Tura … buried my five children with
my own hands … And so many died that all
believed it was the end of the world."
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Causes given at the time of the Plague
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Consequences of the Plague
• Population
• Fertile land (and food) for those who
survived
• Wages for those who survived
• Support for the Church
• Persecution of minorities in Europe,
especially Jewish people
• Incentive to make machines to do human
work
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Epidemics Today
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World Map of Life Expectancies
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Worldwide Deaths from Infectious Diseases
Rank
Cause of death
Deaths 2002
All infectious diseases
14.7 million
% of all
Deaths
25.90%
1 Lower respiratory infections
3.9 million
6.90%
2 HIV/AIDS
2.8 million
4.90%
3 Diarrheal diseases
1.8 million
3.20%
4 Tuberculosis (TB)
1.6 million
2.70%
5 Malaria
1.3 million
2.20%
6 Measles
0.6 million
1.10%
7 Pertussis
0.29 million
0.50%
8 Tetanus
0.21 million
0.40%
9 Meningitis
0.17 million
0.30%
10 Syphilis
0.16 million
0.30%
11 Hepatitis B
0.10 million
0.20%
12 Tropical diseases (6)[12]
0.13 million
0.20%
Note: Other causes of death include maternal and perinatal conditions (5.2%), nutritional
deficiencies (0.9%), noncummunicable conditions (58.8%), and injuries (9.1%) 10
Pathogens
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Agents of Transfer
Mosquito – Malaria, Yellow Fever,
Dengue Fever
Assassin Bug –
Chagas Disease
Flea - Plague
Tsetse Fly – African
Sleeping Sickness
Lice – Typhus & Trench Fever
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World Map of Infectious Diseases
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Herd Immunity Exercise
• Step 1 – Flip your coin once.
• Step 2 – If it is “heads” – stand up – you’re infected
If it is “tails” – stay seated – you’re safe
• Step 3 – Look around the classroom. If an
epidemic were to start somewhere, what is the
likelihood that the whole class will become
infected. In other words, can there be a path to
infection for all?
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Estimated Herd Immunity Thresholds for Vaccine Preventable Diseases
Disease
Diphtheria
Measles
Mumps
Pertussis
Polio
Rubella
Smallpox
Transmission
R0
Herd immunity threshold
Herd Immunity
Saliva
6-7
Threasholds
Airborne
Airborne
droplet
Airborne
droplet
Fecal-oral
route
Airborne
droplet
Social contact
85%
12-18
83 - 94%
4-7
75 - 86%
12-17
92 - 94%
5-7
80 - 86%
5-7
80 - 85%
6-7
83 - 85%
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R is the basic reproduction number, or the average number of secondary infectious
Drug-Resistant Pathogens!
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