1. CHOLERA Vibrio cholerae Brenda Anna Kwambana Wangeci Kagucia

2. 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

3. 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

4. Distribution

5. Causative Agent Discovery 19th Century: What is Cholera? Miasma Theory Blood Generation Theory Germ Theory

6. Causative Agent Discovery John Snow (1813- 1858): Water borne transmission of Cholera (1855)

7. 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

8. Discovery Robert Koch (1843- 1910) 1884: Rediscovers Vibrio cholerae

9. Vibrio cholerae Morphology Gram negative Comma shaped Sheathed, polar flagellum 1.4-2.6µm x 0.5-3µm

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

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

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

13. Secrete enterotoxin Enterotoxin binds to intestinal cells Chloride channels activated Release Large quantities of electrolytes & bicarbonates Fluid hypersecretion Diarrhea Dehydration

14. Transmission Fecal-oral route Entry = oral Discharge = fecal

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

16. 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

17. Diagnosis Clinical symptoms Isolation of V. cholerae from stool –Live V. cholerae in stool (ca. 1.0 x 10 8 cells per ml) –Identification via dark-field microscopy Measurement of serum antibodies using ELISA –Antibacterial antibodies: vibriocidal assays –Antitoxin antibodies

18. 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

19. 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

20. 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.htmlhttp://vm.cfsan.fda.gov/~MOW/chap7.html

21. References, contd. Todar, K.V. cholerae and Asiatic Cholera (2002). Stable URL: http://www.bact.wisc.edu/Bact330/lecturech olera http://www.bact.wisc.edu/Bact330/lecturech olera