Vibrio cholerae

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Vibrio cholerae

  1. 1. VIBRIO CHOLERAEBYYASHWANT KUMARGROUP 8.
  2. 2. HistoryFirst pandemic spreads from India to South, Central Asia, Middle East and RussiaSecond pandemic reaches EnglandPandemics in 1800’s deadlyAll pandemics reach AfricaFirst pandemic reaches Latin America in 1991
  3. 3. Distribution
  4. 4. Causative AgentDiscoveryJohnSnow (1813- 1858):Water borne transmission of Cholera (1855)
  5. 5. 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
  6. 6. DiscoveryRobert Koch (1843- 1910)1884: Rediscovers Vibrio cholerae
  7. 7. Vibrio choleraeMorphology Gram negative Comma shaped Sheathed, polar flagellum 1.4-2.6µm x 0.5-3µm
  8. 8. Physiology Facultative anaerobic Asporogenous Growth stimulated by NaCl pH 6 - 10, Acid labile Temperature 18 - 37ºC
  9. 9. Virulence & Pathogenicity Ingestion of V. cholerae Resistant to gastric acid Colonize small intestineVirulence of Non-toxigenic V. cholerae O1 strain not wellunderstood
  10. 10. ANTIGENIC STRUCTUREHeat-labile flagellar H antigen.O-lipopolysaccharides has 140 serogroups.Serogroup O1 and O139-classic cholera.Others cause cholera like diseases.Serotypes (inaba,ogawa,hikojima) and biotypes(classical,el tor)El tor- hemolysin.Serogroup O139- polysaccharide capsule.
  11. 11. Toxigenic V. choleraePathogenicity Colonization factors (the TcpA pilus) Production of enterotoxin Associated outer membrane proteins on enterocytes e.g. adenylate cyclase
  12. 12. Secrete enterotoxin Enterotoxin binds to intestinal cells Chloride channels activatedRelease Large quantities of electrolytes & bicarbonates Fluid hypersecretion Diarrhea Dehydration
  13. 13. TransmissionFecal-oral routeEntry = oralDischarge = fecal
  14. 14. Transmission  Humans only reservoirs  Bacterium transmitted via contaminated water, food  Carriers: houseflies and other insects  Person to person transmission?
  15. 15. 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
  16. 16. 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
  17. 17. Methods of CureChemotherapeuticAntibiotics (tetracycline)ImmunologicalLocal mucosal immune response to V. choleraeSerological antivibrio antibodiesAntitoxin antibodiesTo Ease SymptomsOral RehydrationIntraveneous Rehydration
  18. 18. 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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