NOTES Molecular Analysis of rRNA and Cholera Toxin Genes Carried by the New Epidemic Strain of Toxigenic

and India. We compared the restriction fragment length polymorphisms of ctrA and rRNA genes (ribotypes) in 27 isolates of V. cholerae 0139 from patients in Bangladesh and India with those of 48 isolates of V. chokrae 01 from patients and 21 V. chokrae isolates from surface waters in Bangladesh, which included 2 0139 and 19 other non-O1 isolates. Ribotyping of the isolates with BglI revealed that all 29 isolates of 0139 vibrios belonged to a single ribotype, suggesting a clonal nature of the infection. However, the 0139 vibrios comprised two cxA genotypes and carried three or more copies of the cx4 gene, and the chromosomal locations of these copies were unlike those of the El Tor or classical vibrios. Analysis of the restriction fragment length polymorphisms of the rRNA genes suggested that V. chokrae 0139 isolates are more closely related to El Tor strains of V. cholerae 01 than were 19 other non-Ol vibrios and 33 classical V. chokrae 01 isolates that were studied. However, further studies are needed to determine whether V. cholerae 0139 originated from mutations and genetic changes in a V. chokrae 01 strain or was due to the acquisition of virulence genes by a previously unknown V. chokrae non-Ol strain. In December 1992, an epidemic of severe acute watery diarrhea clinically resembling cholera occurred in southern Bangladesh; it mainly affected adults and later spread to othe