CHOLERA%20Vibrio%20cholerae

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CHOLERAVibrio cholerae

• Brenda Anna Kwambana
• Wangeci Kagucia

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History

• Origins in India, cases reported as early as
  1563
• About 8 pandemics to date
• 1817-23 First Pandemic
• 1829-50 Second Pandemic
• 1852-60 Third Pandemic Pacini
• 1863-79 Fourth Pandemic
• 1881-96 Fifth Pandemic Koch
• 1899-1923 Sixth Pandemic
• 1961-? Seventh Pandemic
• 1992-? Eighth Pandemic

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History

• First pandemic spreads from India to South,
  Central Asia, Middle East and Russia
• Second pandemic reaches England
• Pandemics in 1800s deadly
• All pandemics reach Africa
• First pandemic reaches Latin America in 1991

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Distribution
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Causative AgentDiscovery

• 19th Century What is Cholera?
• Miasma Theory
• Blood Generation Theory
• Germ Theory

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Causative AgentDiscovery

• John Snow (1813-1858)
• Water borne transmission of Cholera (1855)

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Discovery

• Filippo Pacini (1812-1883)
• 1854 Cholera reaches Florence, Italy. Pacini
  discovers causative agent
• Publishes Microscopical Observations and
  Pathological Deductions on Cholera
• 1965 Bacterium named Vibrio cholerae Pacini 1854

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Discovery

• Robert Koch (1843-1910)
• 1884 Rediscovers Vibrio cholerae

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Vibrio choleraeMorphology

• Gram negative
• Comma shaped
• Sheathed, polar flagellum
• 1.4-2.6µm x 0.5-3µm

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Physiology

• Facultative anaerobic
• Asporogenous
• Growth stimulated by NaCl
• pH 6 - 10, Acid labile
• Temperature 18 - 37ºC

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Virulence Pathogenicity

• Ingestion of V. cholerae
• Resistant to gastric acid
• Colonize small intestine
• Virulence of Non-toxigenic V. cholerae O1 strain
  not well understood

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• Toxigenic V. cholerae Pathogenicity
• Colonization factors (the TcpA pilus)
• Production of enterotoxin
• Associated outer membrane proteins on enterocytes
  e.g. adenylate cyclase

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• Secrete enterotoxin
• Enterotoxin binds to intestinal cells
• Chloride channels activated
• Release Large quantities of electrolytes
  bicarbonates
• Fluid hypersecretion
• Diarrhea

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Transmission

• Fecal-oral route
• Entry oral
• Discharge fecal

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Transmission

• Humans only reservoirs
• Bacterium transmitted via contaminated water,
  food
• Carriers houseflies and other insects
• Person to person transmission?

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Symptoms

• 1-3 day Incubation Period
• Mild diarrhea Sudden severe
  diarrhea
• Mucus and intestinal tissue visible in feces
• Muscle cramps
• Scaphoid abdomen
• Vomiting
• Loss of skin turgor
• Weak pulse

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Diagnosis

• Clinical symptoms
• Isolation of V. cholerae from stool
• Live V. cholerae in stool (ca. 1.0 x 108 cells
  per ml)
• Identification via dark-field microscopy
• Measurement of serum antibodies using ELISA
• Antibacterial antibodies vibriocidal assays
• Antitoxin antibodies

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Methods of Cure

• Chemotherapeutic
• Antibiotics (tetracycline)
• Immunological
• Local mucosal immune response to V. cholerae
• Serological antivibrio antibodies
• Antitoxin antibodies
• To Ease Symptoms
• Oral Rehydration
• Intraveneous Rehydration

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Prevention Control

• Immunization
• Active Immunity induced by
• attenuated V. cholerae
• Toxoid (not good antigen)
• Preventing contamination of food and water e.g.
  boiling water, covering food
• Education
• Personal and domestic hygiene
• Prevention of contamination of water supplies
• Improvement of sewage systems

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References

• Wachsmuth, I., Blake, P. Olsvik. O (Eds.).
  Vibrio cholerae and Cholera Molecular to Global
  Perspectives. Washington, DC ASM Press (1994)
• Drasar, B., Forrest, B. (Eds). Cholera and the
  Ecology of Vibrio cholerae. Bury St Edmunds,
  Great Britain Chapman Hall (1996)
• Perry, J., Staley, J. Lory, S. Microbial Life.
  Sunderland, MA Sinauer Associates, Inc. (2002)
• US Food and Drug Administration. Vibrio cholerae
  Serogroup 01. Stable URL http//vm.cfsan.fda.gov
  /MOW/chap7.html

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References, contd.

• Todar, K.V. cholerae and Asiatic Cholera (2002).
  Stable URL http//www.bact.wisc.edu/Bact330/lectu
  recholera