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BIOL334 > BIOL334 Lecture 4- Cholera > Flashcards

BIOL334 Lecture 4- Cholera Flashcards

1
Q

Is Vibrio cholera invasive?

A

No. The disease occurs at the mucosal surface with no invasion by the microbe into deeper tissues.

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2
Q

What is the infective dose of cholera?

A
  • 1 molecule (the cholera toxin is delivered through the cell wall).
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3
Q

Cholera cases 1986-2016

A
  • Proportions change based on location.
  • In Americas relatively calm for 20-30 years but then a surge occurred in 2011.
  • Due to changes in infrastructure environment and us allowing cholera into the human population.
  • Northern Hemisphere largely exempt.
  • Asia, Africa and South America are usually affected
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4
Q

Who was Pacini and what did he do?

A

Pacini- From Florence, Italy

- 1854 discovered vibrio cholera but ignored due to presence of miasma (bad air) theory.

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5
Q

Who was Koch and what did he discover?

A
  • Koch has greater pre eminence
  • Rediscovered V.cholerae bacterium but didn’t prove it
  • Wasn’t aware of Pacinis work
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6
Q

V. cholera physiology

A
  • Facultative anaerobe
  • Gram negative (thinner peptidoglycan)
  • Rod shaped
  • Asporogenous
  • Growth stimulated by Na Cl
  • Temp 18-37 degrees
  • Can enter VBNC state
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7
Q

What is a serotype of cholera?

A
  • Differences in the sugar composition of heat stable surface O antigen.
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8
Q

Which serotypes cause Cholera outbreaks

A
  • Serotype O139- first identified in Bangladesh and is confined to SE Asia.
  • O1 causes majority
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9
Q

What can you further breakdown serotypes into

A
  • Ribotypes

- This allows precise identification of what is causing an outbreak

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10
Q

Why is V.cholerae considered a true environmental pathogen?

A
  • Found in coastal waters and estuaries (warm coastal waters Bangladesh, Asia and India).
  • Often associated with zooplankton
  • It can use chitin (part of exoskeleton) as a carbon and nitrogen source
  • Can secrete chitinase- nutrient source?
  • Goes up the food chain and spreads
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11
Q

What causes the seasonality of Cholera?

A
  • Agal blooms in warmer temperatures
  • Zooplankton follow algal bloom patterns
  • V. cholera are associated with zooplankton
  • Al three increase with each other
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12
Q

Pathogenicity of V. cholerae

A
  • 2 chromosomes
  • Chromosome 1- house keeping genes and VPI attachment pills, CTx toxin
  • Chromosome 2- integral islands (area of hotspots which you can accumulate drug resistance etc).
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13
Q

Virulence factors of V. cholerae

A
  • Adherence: Accessory Colonisation Factor- sticks to surfaces of sI.
  • Motility- flagella- The flagellar regulatory system positively regulates transcription of a diguanylate cyclase that regulates transcription of haemaglutinin–> intestinal colonisation
  • Binding of haemaglutinin to YcgR gene allows biofilm formation by switching of flagella.
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14
Q

The importance of Quorum Sensing in Cholera infection

A
  • Vibrio cholerae (V. cholerae) is a human pathogen that utilizes quorum sensing to colonize a host and produce its toxin.
  • QS pathways regulate timings of production of colonisation factors and toxins
  • At least 4 sensory inputs function in parallel to regulate QS.
  • Relies on secretion and detection of signalling molecules (autoinducers or AIs).
  • Low cell density= expression of virulence factors (toxin) and biofilm formation
  • High cell density= accumulation of 2 QS HIs repress these traits
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15
Q

How does V.cholerae cause infection?

A
  • Secrete enterotoxin (Stx)
  • Enterotoxin binds to intestinal cells
  • Chloride channels activated
  • Release large quantities of electrolytes and bicarbonates
  • Fluid hyper secretion
  • Diahorrea
  • Dehydration
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16
Q

Vibrio cholerae virulence

A
  • The genes for Ctx toxin are carried by CTX phage. The temperate bacteriophage is inserted into the V.cholerae genome.
  • CTX phage can transmit cholera toxin genes from one V. cholerae to another
17
Q

Symptoms of cholera

A 
profuse watery diarrhea, sometimes described as “rice-water stools”
vomiting.
thirst.
leg cramps.
restlessness or irritability.
18
Q

What is transduction

A

occurs when foreign DNA or RNA is introduced into bacterial or eukaryotic cell via a virus or viral vector

19
Q

What is Transformation

A
  • Uptake of genetic material from the environment by bacterial cells
  • This comes from adjacent lysed bacteria and can include plasmid DNA or fragmented DNA released into the environment
20
Q

What is Conjugation

A
  • Genetic material is transferred from a donor bacterium to a recipient bacterium through direct contact
  • The donor bacterium has a DNA sequence called a fertility factor (F factor).
  • F factor allows a sex pilus to form that attaches to recipient cell
  • Once in close contact the donor can transfer genetic material to recipient
21
Q

Methods for cure for cholera

A
  • Chemotherapeutic: Antibiotics (tetracycline)
  • Immunological: Mucosal immune response, serological anti-vibrio antibodies, antitoxin antibodies
  • Oral rehydration to ease symptoms, intravenous rehydration
22
Q

Management strategies for Cholera

A
  • Cholera cots- 7 inch hole in beds for patients that can’t walk, proper disposal prevents cross contamination.
  • Filtration: cloth of old sari folded 4 times to filter zooplankton bearing cholerae. Villages that did this had a 48% reduction in cholera compared to those that didn’t.
  • Education: sanitation, personal and domestic hygeine
  • Prevention of contamination of water supplies- hygienic disposal of human waste, improvement of sewage systems.
  • Good food hygeine, washing hands after defecation and before cooking.
  • Mapping and data: focusing on high incidence area first, targeted interventions could eliminated 50% of the regions cholera in Sub Saharan Africa
23
Q

Haiti Cholera Epidemic

A
  • Jan 2010
  • Began in October 2010
  • Killed 5000 people
  • By the first 10 weeks cholera spread to all 10 provinces
  • by 2018- 820,000 cases.
  • Major source: UN relief workers
24
Q

Where is there currently a Cholera crisis?

A

Yemen 2016-2020 ~4000 deaths
- due to infrastructure breakdown, bombing, war, sanitation, sewers
-

25
Q

How can technology help to prevent Cholera outbreaks?

A
  • Monitor areas of high rainfall and flooding and intervene before it occurs

BIOL334 (9 decks)

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