Vibrio cholerae

INTRODUCTION:

• Pacini first discovered a comma-shaped bacillus which he described as a Vibrio. 
• John Snow (1813-1858) found the link between cholera and contaminated drinking water in 1854, using spot map.
• Robert Koch Isolated V.cholrae in 1883
• Cholera is caused by Vibriocholera .01 and 0139
• Cholera belongs to category-B of bioterrorism 
• Cholera is WHO notifiable disease
• Father of public health is Dr. John Snow

VIBRIO’S IN NATURE:

• Can survive in extracellular environment.
• The natural habitat of is salt water in coastal areas.
• It is transported in Alkaline pH
• Ingestion of water contaminated by human feces is most common mode of contamination cholera.
• Man is the only natural
• Blood group O+ve are more susceptible

MORPHOLOGY & IDENTIFICATION:

• They appear curved  gram negative aerobic rods and are motile
• Possesing a polar flagellum that shows Darting motility (shooting star)
• V. cholera is able to stay in GIT because of motility
• It is non halophilic 
• V.cholrae is a comma shaped curved rod 2 – 4 µm long
• On prolonged cultivation, vibrio’s become straight rods ,resemble the gram–ve enteric bact.

 ANTIGENIC STRUCTURE & BIOLOGICAL CLASSIFICATION:

• Gardner and Venkatraman’s Classification:

• V.cholrae has O lipopolysaccharide that confer serologic specificity
• Produces indole and reduces nitrates 

V.cholrae – typing

1. 1. Classic
   2.  El Tor

El Tor Vibrio’s:

• The El Tor biotype of vibrio cholerae was first isolated in Egypt
• 7th Pandemic of cholera was caused by El Tor
• The El Tor vibrios produce a Hemolysin and positive results with Voges- Proskauer test
• Resistant to Polymyxin B
• El Tor vibrios has three serotypes- Ogawa(found in India), Inaba, Hikojima.
• It is much harder than classical vibrios, capable of surviving in the environment much longer.
• The severity of illness is much less, with a large proportion of mild and asymptomatic infections.
• Mortality is low and the carrier rate is high.
• Fewer secondary cases in affected families.
• Fast growing in food & Lengthy survival in environment.

V.cholrae- 0-139(Bengal V. cholera:

• V.cholrae 0139 is very similar to epidimologically & clinically V.cholrae .01 El Tor biotype

V.cholrae  0139 Epidemic: 

• The epidemic of cholera caused by V cholerae 0139  was discovered in chennai 
• Signaled beganining of 8th pandemic
• Affected at least 11 countries in southern Asia.
• Differ from E1 tor in production 139 LPS and immunologically related O antigen polysaccharide.
• Most cases of v.parahaemolyticus – associated gastro intestinal illness, regardless of the presentation, are self limited and required neither antimicrobial treatment nor hospitalization.    

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