Prevention of Diarrheal Disease Due to Infection With Enterotoxigenic E. Coli (ETEC)

1. Male or female age ≥18 and ≤ 65 years

2. General good health at the time of first vaccination

3. Female participants of childbearing potential must not be pregnant

4. Females of childbearing potential must agree to use an efficacious hormonal or barrier method of birth control during the study

5. Willingness to participate in the study after all aspects of the protocol have been explained and written informed consent obtained

6. Availability for the study duration, including all planned follow-up visits

7. Intake of atovaquone + proguanil (Malarone) as anti-malaria prophylax according to prescription guidelines mandatory before, during and after travel to Benin

1. Presence of a significant medical or psychiatric condition, which in the opinion of the investigator precludes participation in the study

2. Known or suspected history of drug, chemical or alcohol abuse, as deemed by the investigator/physician; AUDIT > 13 points

3. Known recent history of impaired immune function which, according to the judgement of the investigator could influence the immune response

4. Intends to receive any other investigational vaccine during the study period, or within two weeks prior to study vaccination

5. Intends to donate blood at any time during the study.

6. An acute or chronic medical condition that, in the opinion of the investigator/physician, would render ingestion of the investigational products unsafe or would interfere with the evaluation of responses. This includes, but is not limited to gastrointestinal diseases and autoimmune diseases requiring treatment

7. Any history of psychosis or bipolar disorder or on-going significant mental disorder

8. Regular (daily) use of laxatives or agents which lower stomach acidity (antacids, proton pump inhibitors) less than one week before visit V1

9. Use of any oral or parenteral medication known to affect the immune function (e.g., corticosteroids and others) within 30 days preceding the first vaccination or planned use during the active study period

10. Traveled to ETEC-endemic areas within the last year or visit for > two months in ETEC endemic areas during the last 10 years

11. Receipt of Dukoral or other ETEC or cholera vaccines within 3 years or planned receipt of such vaccine except ETVAX during the study

12. Antibiotic therapy within two weeks prior to the vaccination

13. History of diarrhea in the 7 days prior to vaccination (defined as ≥ 3 unformed loose stools in 24 hours)

14. Any other criteria which, in the investigator's opinion, would compromise the ability of the traveler to participate in the study, the safety of the study, or the results of the study