Historical plagues Flashcards
Historical plagues
Vibrio cholera
yersinia pestis
Vibrio Cholera
gram-negative
curved (vibrio) shaped
Flagellum (monotrichous)
in water
Pili throughout the cell surface
the disease is known as “Cholera”
After ingestion the majority are killed by gastric acid
Surviving ones colonize small intestine and secrete CT
causes watery diarrhea “rice water stool”
History of Cholera
Descriptions of disease found in Sanskrit to the 5th century BC-originated in India
1817 cholera spread beyond Indian subcontient
Transmission
Asymptomatic- shed for a few days, without symptoms, accidental pathogen
Symptomatic-Shed between 2 days and 2 weeks, present in human stool, in environmental water
Pandemics
7 cholera pandemics in total
3rd-death toll:1 million originated in India and spread west
6th-death toll: 800,000+, originated in India and spread east
7th still ongoing
affects 3-5 million people each year, kills 120,000
Asia and Africa
Clinical manifestations
Early illness: vomiting, cramping, fecal matter or bile in stool- up to 1 liter per hour
Late Phase: massive watery diarrhea, characteristic “rice water stool” hypotensive shock, and death
Fever is rare
Dehydration +electrolyte loss: Sunken eyes, dry mouth, cold clammy skin, urine output decreases, etc.
Treatment
Rehydration
aggressive fluid replacement
Antibiotics decrease the volume and duration of diarrhea by 50%
Prevention
High case fatality rate: population density, lack of sanitation and health infrastructure
prevention depends on access to safe water and sanitation
Yersinia pestis
Gram-negative
Coccobacillus
Non-motile
History
discovered in 1984, by Alexandre Yersin, Yersin linked plague with a bacillus, initially named Pasteurella pestis was renamed Yersinia pestis in 1944
2010: researchers established that Y. pestis cause of the black death
2011: first genome isolated from black death victims
Transmission
Parasite of the rat flea, which is also a parasite of rats
hyperparasite
people can become infected: Bitten or scratched by infected animals, inhale respiratory droplets, eat infected animals
Y. pestis pandemics
Justinian plague: 541 to 750/767 CE
Second pandemic: 1346 to the 18th century,Europe +Asia,lack of travel
3rd pandemic: 1772 china, spread worldwide
Black death pandemic
from 1346 to 1353
Death toll: 75-200 million
Originated in Asia and through Africa +Europe
Jumped continents-merchant ships-rats lived on
Diagnosis
sole disease by swollen lymph nodes referred to as buboes
classic plague doctor: Wide-brimmed hat-Doctor, Bird beak mask- birds carried plagues, Red glass eyepieces-ward off evil spirits, Long black overcoat tucked around mask-wax, wooden cane,leather breeches under overcoat
Manifestations
Skin ulceration where bit
reported as carbuncles and ulcers
pustules, spots,petechiae,brusing,gangrene
five main forms: Bubonic, septicemic, pneumonic, meningeal,pharyngeal
Bubonic
Most common
Lymph nodes near site of exposure become swollen and extremely painful-armpits,neck, and groin
Fever,headache, chills, fatigue, vomiting,etc.
Antibiotic treatment reduces fatality from 60% to less than 5
Septicemic
transmitted directly into the bloodstream-no obvious swollen lymph nodes
cell and tissue death, or necrosis and gangrene- pulls blood from extremities
Fever, chills, malaise, and gastrointestinal symptoms
with no antibiotics, a 30-50% mortality rate
Pneumonic
Inhaling bacteria
most uncommon
Flulike illness rapidly to pneumonia
coughing, chest pain, and bloody sputum
high mortality rate, even with treatment-80%
Medieval treatment
Divine punishment from God: Repent-brotherhood of the flagellants: town to town, whipping self
Miasma theory: Bad air spreads sickness, foul winds that carried the Plague had risen from oceans in the south
To bring balance: Bloodletting- cutting a vein to drain away blood, barber, specific vein,rich used leeches -“bad blood”
