The current multi-dose schedules for both Dukoral and Shanchol™ have restricted the application of the oral cholera vaccine in situations where they are most needed. Getting a vaccine to the same people twice poses difficulties in the control of cholera in both endemic and epidemic settings. In a study performed in a cholera-endemic area in Kolkata, India it was found that Shanchol™ induces significant vibriocidal responses even after a single dose .This study is designed to determine the protective efficacy and duration of protection offered by a single dose regimen and is not intended to replace the recommended 2 dose regimen in endemic areas. This will be useful for epidemics and outbreaks situation.