The purpose of the study is to determine if immunization with dscCfaE with or without a modified E. coli heat labile enterotoxin, LTR192G, is safe and immunogenic when administered transcutaneously using a skin wet-patch. If the vaccine is found safe and adequately immunogenic in humans, a phase 2b vaccination/challenge study would be undertaken to further evaluate vaccine safety and allow a preliminary assessment of efficacy. With favorable evidence for safety, immunogenicity, efficacy, complemented by advances in standard methodology to combine multiple adhesins with an appropriate LT enterotoxoid form, a multivalent vaccine would be constructed and evaluated for further clinical development.