Reemergence of epidemic Vibrio cholerae O139, Bangladesh

During March and April 2002, a resurgence of Vibrio cholerae 0139 occurred in Dhaka and adjoining areas of Bangladesh with an estimated 30,000 cases of cholera. Patients infected with 0139 strains were much older than those infected with 01 strains (p<0.001). The reemerged 0139 strains belong to a single ribotype corresponding to one of two ribotypes that caused the initial 0139 outbreak in 1993. Unlike the strains of 1993, the recent strains are susceptible to trimethoprim, sulphamethoxazole, and streptomycin but resistant to nalidixic acid. The new 0139 strains carry a copy of the Calcutta type CTXCalc prophage in addition to the CTXET prophage carried by the previous strains. Thus, the 0139 strains continue to evolve, and the adult population continues to be more susceptible to 0139 cholera, which suggests a lack of adequate immunity against this serogroup. These findings emphasize the need for continuous monitoring of the new epidemic strains.