Vibrios are gram-negative, highly motile curved rods with a single polar flagellum. Until 1992, cholera was

caused by only two serotypes, Inaba and Ogawa, and two biotypes, classical and El Tor, of toxigenic Vibrio

cholera O1. These organisms may be identified by biochemical tests though bacterial culture on selective media,

by agglutination in O group 1 specific antiserum directed against the lipopolysaccharide component of the cell

wall and by demonstration of their enterotoxigenicity with PCR. Vibrio cholerae O139 is a new strain of cholera

first isolated in 1993, which appears to have been derived from the El Tor biotype by retaining the epidemic

potential of O1 strains and producing the same cholera enterotoxin though it has lost the characteristic O1

somatic antigen. This serovar is identified by 1) absence of agglutination in O group 1 specific antiserum; 2)

agglutination in O group 139 specific antiserum; and 3) the presence of a polysaccharide capsule. VC O139

strains undergo rapid genetic changes, which facilitates bacteria gaining resistance to antibiotics. Furthermore,

previous infections with serogroup O1 does not provide immunity against O139. It is anticipated that the extent

and rapidity of the spread of this disease caused by O139 is most likely to set off the beginnings of the next

cholera pandemic in the world. V. cholerae causes diarrhea via colonization in the small intestine and production

of a potent cholera toxin. Because of the clinical and epidemiological severity, it is critical to determine the

presence of V. cholerae as quickly as possible in clinical specimens, water and food so that appropriate

monitoring and effective preventive measures can be undertaken by public health authorities.