ABSTRACT
A total of 286 strains of Vibro Cholerae were isolated and tested over a period of five years. The strains were identified by standard methods and confirmed by slide agglutination tests with polyvalent, Ogawa and Inaba antisera. The non-agglutinating strains were tested with O-139 antisera. The maximum number of cases were found in the age group of 0-10 years. The number of females affected was more than the males. V. cholerae O-139 was isolated in the year 1998 and then again in 2000. V. cholerae serotype Inaba was found only in the year 1999. All of the other isolates belonged to the serotype Ogawa. The periodic shift between O1 and O-139 serogoups is reminiscent of the shifts from the Ogawa to the Inaba serotypes periodically witnessed among V. cholerae, possibly mediated by the immune pressure in the population.