22 - Plague Flashcards
Fatality rate if untreated
30-100%
Deaths due to the black plague
200M (~50% of pop)
Describe Yesinia pestis
Gram negative bacteria
Coccobaccilus (rod shaped)
Facultative anaerobe (can grow under anaerobic or aerobic conditions)
Incubation period, symptoms and three clinical forms of plague
3-7 days incubation
Fever, chills, aches, weakness, vomiting, nausea, gangrene
Clinical forms:
- bubonic plague (most common)
- septicemic plague
- pneumonic plague
Mortality, infection and transmission of bubonic
40-60% mortality (untreated)
Infection of lymph tissue (caused by flea bite)
No human to human transmission
Mortality, infection and transmission of septicemic
100% mortality (untreated)
Bloodstream
Results from pneumonic or bubonic plague or directly from flea bites
No human to human
Mortality, transmission, infection of pneumonic
Infection in lungs
100% mortality
Least common form
Human to human
Most virulent form
Antibiotic treatment of plague
Can be treated with antibiotics
Pandemics 1, 2 and much of 3 predated antibiotics
Plague vaccine?
Exists, given to lab personnel working with Y pestis
Three plague pandemics
- Justinian (550-750 AD = 25M deaths)
- Black death (14th century = 100-200M deaths)
- 3rd pandemic (mid 1800s = 10M deaths)
Early theory on cause of plague
Alignment of planets
Miasma theory
Who identified Y pestis
Alexandre Yersin
Hong Kong plague in 1894
Rat/flea connection
Rat flea (Xenopsylla cheopsis) responsible for transmission
Paul-Louis Simond
Two routs of human-human transmission
- Pneumonic plague (aerosolization of Y pestis)
- Human ectoparasites (human flea)
Yersinia pestis reservoir
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
Siege of caffa and the black death*
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)
Great Plague of London
1665-1666
20% population
Effects of black death on genetics
- mitochondrial DNA more variable prior to BD
- drop in genetic diversity bc of population loss in 1340s and 1660s
What is Familial Mediterranean Fever
- autosomal recessive disorder
- cause of premature death in eastern Mediterranean pops (kidney damage, inflammation)
- recessive mutations of pyrin gene cause FMF
FMF vs healthy (non-FMF) with Y pestis
Healthy: YP virulence resistance factor inhibits pyrin = evasion of host
FMF patient: altered pyrin, not inhibited by resistance factor, inhibits YP replication
Third plague pandemic? Manchuria
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)
Who was Joseph Kinyoun
Quarantine officer
Microbiologist
Monitored plague ships bound from Honolulu
Plague in Hawaii
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
Who was Rupert Blue
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
Affect of plague on black-tailed prairie dog and black-footed ferret
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)
