MOLECULAR SUBTYPING OF TOXIGENIC VIBRIO-CHOLERAE-O139 CAUSING EPIDEMIC CHOLERA IN INDIA AND BANGLADESH, 1992-1993

Since October 1992, >150,000 cases of cholera have been reported from India and Bangladesh; the great majority of Vibrio cholerae isolates b elong to the newly established serogroup O139. To better understand th e interaction of genetic and epidemiologic factors responsible for the ir sudden appearance and rapid spread, representative toxigenic V. cho lerae O139 isolates were molecularly characterized and compared with a set of toxigenic V. cholerae O1 and non-O1/non-O139 strains. DNA sequ ences of the cholera toxin B subunit gene and multilocus enzyme electr ophoresis markers of V. cholerae O139 strains were identical to those of V. cholerae O1 isolates of the seventh pandemic. Two distinct ribot ypes and four pulsed-field gel electrophoretic patterns were observed for O139 strains. V. cholerae O139 strains were very similar to V. cho lerae O1 strains of the seventh pandemic but clearly different from th e toxigenic V.cholerae strains of serogroups other than O1 and O139.