Travelers' Diarrhea (TD) Vaccine Pivotal Efficacy Study

Inclusion Criteria: * 18-64 years of age at date of first vaccination * Good health as determined by medical history and physical inspection * Females of child-bearing potential must have a negative pregnancy test prior to first vaccination in teh Country of Origin; females of child-bearing potential must agree not to become pregnant throughout the duration of the study * Subjects must have planned travel to an area within 3 hours traveling distance of Mexico City, Cuernavaca, Guadalajara, Oaxaca, or San Miguel de Allende, Mexico or Antigua, Quezaltenango, Guatemala City, or Solola, Guatemala for a minimum duration of stay 7 days (no maximum stay is specified for inclusion). * Subject must be able to communicate in English Exclusion Criteria: * Abnormalities as determined by the Investigator/clinician during physical inspection * Participated in research involving investigational product within 30 days before planned date of first vaccination * Ever received LT, ETEC, or cholera vaccine * History of diarrhea while traveling to a developing country within the last year * Women who are pregnant or breastfeeding * Clinically significant underlying enteric, pulmonary, cardiac, liver or renal disease * History of Irritable Bowel Syndrome * Seizure disorder within the last year * Current use of immunosuppressive therapy (excluding inhaled steroids) or current immunodeficiency * Known or suspected alcohol abuse or illicit drug use within the last year * Medical history of HIV, HB…