22 - Plague

Question 1

Fatality rate if untreated

Answer 1

30-100%

Question 2

Deaths due to the black plague

Answer 2

200M (~50% of pop)

Question 3

Describe Yesinia pestis

Answer 3

Gram negative bacteria
Coccobaccilus (rod shaped)
Facultative anaerobe (can grow under anaerobic or aerobic conditions)

Question 4

Incubation period, symptoms and three clinical forms of plague

Answer 4

3-7 days incubation

Fever, chills, aches, weakness, vomiting, nausea, gangrene

Clinical forms:
- bubonic plague (most common)
- septicemic plague
- pneumonic plague

Question 5

Mortality, infection and transmission of bubonic

Answer 5

40-60% mortality (untreated)

Infection of lymph tissue (caused by flea bite)

No human to human transmission

Question 6

Mortality, infection and transmission of septicemic

Answer 6

100% mortality (untreated)

Bloodstream
Results from pneumonic or bubonic plague or directly from flea bites

No human to human

Question 7

Mortality, transmission, infection of pneumonic

Answer 7

Infection in lungs

100% mortality
Least common form

Human to human
Most virulent form

Question 8

Antibiotic treatment of plague

Answer 8

Can be treated with antibiotics

Pandemics 1, 2 and much of 3 predated antibiotics

Question 9

Plague vaccine?

Answer 9

Exists, given to lab personnel working with Y pestis

Question 10

Three plague pandemics

Answer 10

• Justinian (550-750 AD = 25M deaths)
• Black death (14th century = 100-200M deaths)
• 3rd pandemic (mid 1800s = 10M deaths)

Question 11

Early theory on cause of plague

Answer 11

Alignment of planets

Miasma theory

Question 12

Who identified Y pestis

Answer 12

Alexandre Yersin
Hong Kong plague in 1894

Question 13

Rat/flea connection

Answer 13

Rat flea (Xenopsylla cheopsis) responsible for transmission
Paul-Louis Simond

Question 14

Two routs of human-human transmission

Answer 14

• Pneumonic plague (aerosolization of Y pestis)
• Human ectoparasites (human flea)

Question 15

Yersinia pestis reservoir

Answer 15

Great gerbil (harbors fleas with YP)
Decreases in pop due to environmental factors (e.g. drought) leads to dead gerbils = fleas need to find new home

Question 16

Siege of caffa and the black death*

Answer 16

1346
Caffa besieged by Mongols (Tartars) for ~3 years
Toward end of siege, epidemic of plague in Tartars = 1000s deaths/day

1000s of plague victims catapulted into city
Plague epidemic developed in Caffa

Italians fleeing Caffa transported plague to Mediterranean ports (Europe)

Question 17

Great Plague of London

Answer 17

1665-1666
20% population

Question 18

Effects of black death on genetics

Answer 18

• mitochondrial DNA more variable prior to BD
• drop in genetic diversity bc of population loss in 1340s and 1660s

Question 19

What is Familial Mediterranean Fever

Answer 19

• autosomal recessive disorder
• cause of premature death in eastern Mediterranean pops (kidney damage, inflammation)
• recessive mutations of pyrin gene cause FMF

Question 20

FMF vs healthy (non-FMF) with Y pestis

Answer 20

Healthy: YP virulence resistance factor inhibits pyrin = evasion of host

FMF patient: altered pyrin, not inhibited by resistance factor, inhibits YP replication

Question 21

Third plague pandemic? Manchuria

Answer 21

Began in China mid 19th century
Spread to all inhabited continents

Manchuria: 60,000 deaths, pneumonic form predominant, originated from tarbagan marmots (they were trappers)

Question 22

Who was Joseph Kinyoun

Answer 22

Quarantine officer
Microbiologist
Monitored plague ships bound from Honolulu

Question 23

Plague in Hawaii

Answer 23

1900 Honolulu Chinatown
Placed under quarantine (military)

Torched buildings where bubonic plague was (17 fires)
Fires got out of control, 7000 homeless residents “The Great Fire”

71 cases, 61 deaths
Cases until 1949

Question 24

Who was Rupert Blue

Answer 24

Replaced Kinyoun in San Francisco
M.D.
Hired homeless men to kill rats, improved sanitation of Chinatown/San Fran

1900-1904: 121 cases of plague (113 deaths)
1904-1905: no new cases

Question 25

Affect of plague on black-tailed prairie dog and black-footed ferret

Answer 25

Black-tailed prairie dogs are very susceptible: plague causes total colony loss

Black-footed ferret not susceptible, but depends on prairie dog for source of food and uses its burrows (endangered species)