1. Dr. Jyotsna Agarwal Dept. Microbiology
Vibrio cholerae
Dr. Jyotsna Agarwal
Dept. Microbiology

2. Cholera: Introduction
Transmitted to humans via contaminated food and water
Part of normal flora of brackish water and estuaries
associated with algal blooms (plankton), which are influenced by the temperature of the water. 8
- lots of pictures
Human beings are also one of the reservoirs of the pathogenic form of Vibrio cholerae.”8

3. Epidemiology of Vibrio cholerae
Cholera recognized for more than two millennia with sporadic disease and epidemics
Endemic in communities with poor sanitation
Seven pandemics (possible beginning of 8th) since 1817
Human carriers and environmental reservoirs

4. Historical Perspective:
First Pandemic
spread out of India to
Europe
spread from India -> Middle
East (reaching Turkey &
Persia) -> Far East
(Singapore, Japan, Philippines)
Second pandemic
Entered US through NY and New Orleans -> proceeded through entire country
PICTURE: Title: 'Hoping for the Spread of Cholera', c Caption: 'Hoping for the Spread of Cholera', c Lithograph featuring a caricature of an undertaker in hat and tailcoat, gleefully rubbing his hands in anticipation of increased business from a cholera epidemic. He is seen looking down at a paper reporting recent deaths. The first major cholera epidemic struck England in 1831, and was initially attributed to 'miasma' (foul vapours in the atmosphere). However, observations made by John Snow ( ) during the epidemics of 1848 and 1854 established the role of polluted water in the spread of the disease.
had unusual virulence1
disease was new to the area -> thought it was a new disease

5. Historical Perspective: Identification
Filippo Pacini identified curved or comma shaped bacterium associated with this disease, which he called Vibrio cholerae
1883- Rober Koch isolated the bacteria
PICTURE: He published a paper in 1854 entitled, "Microscopical observations and pathological deductions on cholera" in which he described the organism and its relation to the disease. His microscopic slides of the organism were clearly labeled, identifying the date and nature of his investigations (see figure).
“He correctly described the disease as a massive loss of fluid and electrolytes due to the local action of the vibrio on the intestinal mucosa, and recommended in extreme cases the intravenous injection of 10 gram of sodium chloride in a liter of water - - later found to be very effective.”3

6. Historical Perspective:
John Snow hypothesized water as primary reservoir for transmission
Broad Street pump incident
56 deaths in 2 days
PICTURE: It offers his views on cholera and other epidemic diseases that were troublesome during the mid-1800s. The writings illustrate his manner of epidemiologic thinking, and how he used available clinical and population-based evidence to address the potential etiology of selected infectious diseases.

7. Recent Cholera Pandemics
7th pandemic:
V. cholerae O1 biotype El Tor
Began in Asia in 1961
8th pandemic (??)
V. cholerae O139 Bengal
Began in India in 1992 and spread to Asia, Europe and U.S.

8. Cholera affected countries

9. General Characteristics of Vibrio
Similarities to Enterobacteriaceae
Gram-negative
Facultative anaerobes
Fermentative bacilli
Differences from Enterobacteriaceae
Polar flagella
Oxidase positive

10. Vibrio spp. (Family Vibrionaceae) Associated with Human Disease

11. General Characteristics of Vibrio
Comma-shaped bacilli
pH range for growth on media pH
V. cholerae grow without salt, Most other vibrios are halophilic

12. Taxonomy of Vibrio cholerae
>200 serogroups based on somatic O-antigen
O1 and O139 serogroups are responsible for epidemic cholera
O1 serogroup subdivided into
Two biotypes: El Tor and classical
Three serotypes: ogawa, inaba, hikojima
Non-cholera vibrio (NCV) or non- agglutinating vibrios (NAG) or non-O1 vibrio cholerae)

14. Difference between El Tor & classical Vibrio cholerae

15. Pathogenesis of V.cholerae
Incubation period: 2-3 days
High infectious dose
Abrupt onset of life-threatening watery diarrhea
Rice-water stools:
Colorless
Odorless
Speckled with mucus

16. Pathogenesis of V. cholerae
Cholera toxin leads to profuse loss of fluids and electrolytes (Na, K HCO3)
A-B type of toxin, receptor GM1, increase intracellular cAMP
Death attributable to:
Hypovolemic shock
Metabolic acidosis

17. Laboratory Identification of Vibrios
Transport medium or holding medium
- Cary-Blair
Venkatraman Ramakrishnan medium- liquid
Enrichment medium - alkaline peptone broth

18. Yellow colonies on TCBS
Selective/differential culture medium - TCBS agar
V. cholerae grow as yellow colonies
Gram stain
Biochemical and serological tests
Motility- Darting motility on hanging drop preparation

19. Treatment & Prevention of cholera
Untreated: 60% fatality
Treated: <1% fatality
Rehydration & supportive therapy
Oral
Intravenous
Doxycycline or tetracycline
Water purification, sanitation & sewage treatment
Vaccines

20. Summary General characters of vibrio, history Vibrio cholerae
Cholera: mode of spread, clinical features
Laboratory diagnosis
Treatment/prevention