prevalence and molecular characteristics of vibrio species in pre ...

2.8 Human pathogenic Vibrio
2.8.1 Vibrio cholerae
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Cholera has been recognized as a fatal disease since 1817 and six pandemics
have already swept over the world (Suzita et al., 2009) and the 7 th and 8 th pandemics
are still progressing (Kaysner, 2000). Vibrio cholera is transmitted to humans via
contaminated food, water, raw seafood or direct infection from food handlers (Suzita
et al., 2009, Thompson et al., 2004). Cholera is characterized by profuse acute
diarrhoea (rice water), vomiting, dehydration and death within 24 hours if left
untreated (Suzita et al., 2009). The pathogenesis of this organism in the intestine is
characterized by adherence to the epithelium and production of an enterotoxin
(cholera toxin) which leads to intense watery diarrhoea. In addition to the toxin, the
toxin coregulated pilus is essential for the micro colonization of the intestinal
epithelium (Thompson et al., 2004).
Currently more than 200 serogroups of V. cholera are identified based on the
somatic O antigen. Vibrio cholera O1, O139, non-O1, non-O139 and O141 are the
deferent O strains that cause diarrhoea throughout the world. V. cholerae O1 has two
serogroups Inaba and Ogawa and two biotypes namely, Classical and El Tor (Ganesh
et al., 2010, Suzita et al., 2009). Serogroup O1 and O139 are responsible for the
epidemics and pandemic occurrences of cholera and non-O1 and non-O139 are less
virulent forms found in patients. V. cholerae O141 causes cholera-like diarrhoea and
bacteraemia in the United States (Crump et al., 2003).
2.8.2 Vibrio parahaemolyticus
Vibrio parahaemolyticus is a Gram negative, mesophilic and halophilic rod-
shaped bacterium found in the estuarine environment, especially in shellfish, coastal
fish and seafood. Consumption of raw, under cooked or contaminated shellfish, fish
and seafood is the method of transmission of this bacterium to humans. It causes
gastroenteritis, nausea, watery diarrhoea, vomiting, abdominal cramps, low grade
fever, chills and sometimes bloody diarrhoea (Cabanillas-Beltrán et al., 2006). V.
parahaemolyticus produces toxins: thermo-stable direct haemolysin (TDH), encoded