Cholera Anti-Secretory Treatment Trial

Inclusion Criteria: 1. Willing and able to understand and provide written informed consent 2. Healthy male and female adults, age 18 to 44 years (inclusive), without clinically significant medical history, physical or clinical laboratory abnormalities (as per protocol-defined acceptable ranges), and protocol-defined abnormal electrocardiogram results at screening 3. All women must have a negative serum pregnancy test at screening and one day prior to challenge. 4. Agreement by participants to use an adequate method of contraception\* during the study and for 4 weeks before and after the challenge. 5. Able to pass a written examination (comprehension assessment test) with a score of ≥ 70%, in order to demonstrate their comprehension of this study. If a participant scores at least 50%, then they will be given one more opportunity to re-test after further re-education. 6. Willing and able to comply with the study requirements and procedures. * Adequate contraception is defined as a contraceptive method with failure rate of less than 1% per year when used consistently and correctly and when applicable, in accordance with the product label; includes, but is not limited to, barrier with additional spermicidal foam or jelly, intrauterine device, hormonal contraception (started at least 4 weeks prior to study enrollment), or women who have intercourse limited to men who underwent vasectomy. Exclusion Criteria: 1. Clinically significant history of immunodeficiency, cardiovascular disease, respiratory disease, endocrine disorder, liver disease, renal disease, gastrointestinal disease, anal or rectal disorders, neurologic disease, 2. Current nicotine use or drug, alcohol abuse within the past 6 months 3. Recipient of bone marrow or solid organ transplant 4. Use of systemic chemotherapy in the past 5 years 5. Has a malignancy (excluding localized non-melanoma skin cancers) or lymphoproliferative disorders diagnosed or treated within the past 5 years 6. Received or plans to receive systemic immunosuppressive therapy, radiation therapy, parenteral or high-dosage inhaled steroids (\> 800 µg/day of beclomethasone dipropionate or equivalent) within 6 months prior to the enrollment through 28 days after challenge 7. Have a history of hospitalization for psychiatric illness, suicide attempt, or confinement for danger to self or others, within the past 10 years. Participants with a psychiatric disorder (not meeting exclusion criteria, e.g., attention-deficit hyperactivity disorder) that is controlled for a minimum of 3 months and the investigator has determined that the participant's mental status will not compromise the participant's ability to comply with protocol requirements may be enrolled 8. Have an elevated blood pressure, systolic ≥ 150 mmHg or diastolic ≥ 90 mmHg, before challenge 9. Taking any of the the protocol-defined drugs that are metabolized by CYP2C9 or any of the following psychiatric medications: aripiprazole, carbamazepine, chlorpromazine, chlorprothixene, clozapine, divalproex sodium, fluphenazine, haloperidol, lithium carbonate, lithium citrate, loxapine, mesoridazine, molindone, olanzapine, perphenazine, pimozide, quetiapine, risperidone, thioridazine, thiothixene, trifluoperazine, triflupromazine, or ziprasidone 10. History of Guillain-Barré Syndrome 11. Too low or too high a body mass index (BMI \< 18.5 or \> 39) 12. Has an abnormal stool pattern defined as fewer than 3 stools per week or more than 2 stools per day within the past 6 months, and any loose stools (grade 3 or higher) during the 1-2 day acclimation period before challenge 13. Has regularly used laxatives in the past 6 months 14. Has a history of eating disorders (e.g. anorexia or bulimia) within the past 10 years 15. Known allergy or previous severe adverse effect to all of the following antibiotics: ciprofloxacin (or quinolones), azithromycin and doxycycline. 16. Previously received a licensed or investigational cholera vaccine, within 10 years 17. History of cholera or enterotoxigenic Escherichia coli (ETEC) infection (lab-confirmed natural infection or experimental challenge), within 10 years 18. Travel to a cholera-endemic area in the past 5 years 19. Pregnant or nursing 20. Positive serology for human immunodeficiency virus (HIV), hepatitis B antigen, or hepatitis C antibody 21. Protocol-defined clinically abnormal 12-lead electrocardiogram (ECG) at screening in the judgment of the Investigator, or based on the formal 12-lead ECG reading by a cardiologist; history of any cardiac abnormalities, including conduction abnormalities such as Wolff-Parkinson-White, dysrhythmias, or coronary artery disease 22. Presence of a clinically significant abnormality on physical examination, including (but not limited to): pathologic heart murmur, lymphadenopathy, hepatosplenomegaly, large abdominal scar of unclear origin 23. Has poor venous access, defined as the inability to obtain screening blood tests after three attempts 24. Currently on, or plans to be on, antibiotics (e.g., doxycycline) within 14 days prior to challenge and through 28 days after challenge 25. Presence of an acute illness or fever (\> 100.4°F) within 72 hours of admission to the inpatient Clinical Research Unit 26. Taking any prescription or over-the-counter medications that contain aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), antacids, proton pump inhibitors (PPIs), anti-diarrheals, etc. within 72 hours prior to challenge 27. Received an investigational product within 30 days prior to randomization (90 days prior to randomization for monoclonal antibodies) or planned to participate in another research study involving an investigational product during the conduct of this study 28. Participants must not have donated blood in 8 weeks prior to study entry and agreed to not donate blood during and for 4 weeks following their active participation in this study 29. Lack of ability to fully understand the informed consent 30. Any other condition(s) that in the opinion of the investigator would jeopardize the safety or rights of a participant participating in the trial or would render the participant unable to comply with the protocol