1.  Cholera is a highly infectious disease. Infection occurs by the oral route through contaminated food and drinks. Water born epidemics are reported. The source of infection is either a case or a carrier.  The pathogenesis of cholera is dependent on colonization of the small intestine by the organism and secretion of enterotoxin.  V. cholera is not an invasive organism, so it does not reach blood stream (no bacteremia).

4.  Subcultures are subsequently made on alkaline agar or TCBS (Thiosulfate-bile sucrose medium) medium on which V. cholerae produces yellow colonies.

5. The growth is subsequently identified by: 1. Microscopic examination Fresh examination demonstrates the actively motile vibrios under dark field microscopy 2. Gram-stained smears Show Gram-negative comma-shaped bacilli, non-spore forming and non-capsulated 3. Biochemical reactions and cholera red reaction 4. Agglutination with anti-O1 and anti O139 antisera.

6. Molecular methods:  PCR amplification has been used for the detection of the cholera toxin A subunit gene in the rice water stools.  DNA probe for detecting toxigenic V. cholerae. Treatment:  The most important part is restoration of fluid and electrolyte balance to correct dehydration and acidosis by giving intravenous fluids.  Antibiotics (tetracyclines) have a secondary role.

7. Prevention:  Public health measures directed to sewage disposal, clean water supply, isolation of cases (similar to s. typhi)  Chemoprophylaxis by tetracyclines to exposed persons.  Vaccines:  Extract of killed bacteria given I.M.  Oral vaccine consisting of inactivated V. cholerae with B subunits.  A live attenuating oral vaccine

8.  The efficiency of this vaccine in protection is disputed as it stimulates antibacterial but not antitoxic antibodies.  Attempts to develop new vaccines given orally to protect against cholera toxin are under trails.

9. VIBRIO PARAHAEMOLYTICUS  This is a marine vibrios requires a high Na cl concentration to grow (halophilic).  It produces blue-green colonies on TCBS medium.  It is associated with food poisoning due to eating shell fish or raw fish the clinical picture caused by V. parahaemolyticus varies from mild to quite severe watery diarrhea.  The illness is self limited.

11. Plesiomonas  Related to vibrios, but halophilic.  Plesiomonas shigeloides sometimes causes water-borne outbreaks of diarrhea in warm countries.  (halophilic -requires a high conc. of Nacl to grow).