(Section C: Bacteriology) Lecture 19: Flashcards
Describe:
Yersinia
* Gram stain
* Shape
* Strains
- Gram negative
- Rod shaped
- Bacteria
- 3 strains pathogenic to humans
What are the 3 strains of Yersinia that are pathogenic for humans?
- Y. enterocolitica
- Y. pseudotuberculosis
- Y. pestis
Y. enterocolitica
Causes “yersiniosis” - a rare cause of diarrhea and abdominal pain
Y. pseudotuberculosis
Primarily an animal pathogen that can cause tuberculosis-like symptoms in animals, enteritis in humans
Y. pestis
Cause of the plague
What are key characteristics of Yersinia pestis?
- Extraordinarily virulent pathogen
- May cause death in 2-4 days by sepsis and/or overwhelming pneumonia with respiratory failure
- NOT an efficient colonizer of humans
History of Yersinia pestis discovery and namesake
- Discovered by Alexandre Yersin (namesake) and Kitasato Shibasaburo in the late 1800s
- Pestis = Pestilence (contagious or infectious epidemic disease)
Plague:
- Incubation period
- Death period
- 3-7 days
- 2-4 days
Plague:
General signs and symptoms (early stage)
Sudden onset of:
1. Fever
2. Chills
3. Headaches
4. Muscle pain
5. Weakness
Plague:
Signs and symptoms (lymph nodes)
Painful swellings (buboes) of lymph nodes in:
* Armpits
* Legs
* Neck
* Groin
Plague:
Signs and symptoms (late stage)
- High fever
- Delirium
- Mental deterioration
- Large blackish pustules that burst
- Vomiting of blood
- Bleeding in the lungs
What were the 3 plague pandemics?
- “Plague of Justinian”
- “Black Death”
- Mid 19th Century
Plague of Justinian
* Date
* Cause
* Area
* Death
- Started in the 6th century (541-542 AD)
- Caused by Yersinia pestis
- Mediterranean, Italy and throughout Europe
- ~50% of population died, around 100 million people killed
What happened after the initial plague during the “Plague of Justinian”?
Continued in cycles for 200 years until 750 AD
* Disappears for ~800 years
Black Death
* Date
* Cause
* Area
* Death
- Late 1340s (spread to Europe)
- Caused by Yersinia pestis
- Originated in Asia, reached Europe in late 1340s
- ~100 million globally, ~25 million Europeans (1/3 of population)
What was society’s reaction to the Black Death during its time?
- No idea what was going on
- No (real) treatment
- Believed it was “God’s anger” or “Satan’s influence”
- Persecuted strangers, minorities, and witches
- European social order and such was destroyed
What was the Feudal System?
Political and social structure prevalent in Europe at the time of the Black Death
* Little opportunity for advancement
* Few people had everything, most had little
What did the Black Death do to the Feudal System?
Created vacant towns and farms (positions of authority need to be filled)
* Created new opportunities for the peasants
How was it discovered that Y. pestis caused the Black Death?
Analyzing genomes in the feet of bodies buried in London
Mid-19th Century Pandemic
* Date
* Cause
* Area
* Deaths
- 1850s, considered active until 1959
- Caused by Yersinia pestis
- Started in China, spread to US in 1900
- 12 million deaths in China and India alone
Pathogenesis of Yesinia pestis:
* Where does it live?
* What type of pathogen is it?
* Describe mechanism it transfers by
- Lives in rodents and are transmitted by fleas
- Zoonotic pathogen
Mechanism of transfer
* Causes “blocking” in the flea (biofilm formation in the proventriculus)
* Causes fleas to “starve”
* Fleas regurgitate bacteria into organisms it feeds on
What is the infective dose of Yersinia pestis?
~10 cells
* Very infective, many bacteria require hundreds of cells to cause infection
Where does Yersinia pestis initially survive and grow?
In innate immune cells
Where does Y. pestis replicate?
In lymphoid organs
* Spleen
* Bone marrow
* Lymph nodes
* Liver
