Trial Evaluating Ambulatory Treatment of Travelers' Diarrhea

The study will be a multi-site, randomized, double-blind, controlled clinical trial among ambulatory deployed personnel. Patients presenting for care will be clinically assessed and a determination made as to whether they have acute watery diarrhea (AWD) or acute dysentery/febrile diarrhea (ADF). For the AWD arm, patients will be randomized to receive 1 of 3 regimens: (1) rifaximin 1650 mg as a single dose plus loperamide 4 mg initially followed by 2 mg after each unformed stool, not to exceed 16 mg/day for 2 days (120 subjects); (2) azithromycin 500 mg as a single dose plus loperamide 4 mg initially followed by 2 mg after each unformed stool, not to exceed 16 mg/day for 2 days (120 subjects); or (3) levofloxacin 500 mg as a single dose plus loperamide 4 mg initially followed by 2 mg after each unformed stool, not to exceed 16 mg/day for 2 days (120 subjects). For the ADF arm, patients will be randomized to receive 1 of 2 regimens: (1) azithromycin 1000 mg as a single dose plus loperamide 4 mg initially followed by 2 mg after each unformed stool, not to exceed 16 mg/day for 2 days (75 subjects); or (2) azithromycin 1000 mg as a single dose without loperamide (75 subjects). Study Procedures (Brief): Baseline exam as well as blood and stool samples will be collected at initial clinic visit. Clinical assessments will be performed at 24 hours, 72 hours, and 7 days. In addition, microbiological cure will be evaluated at 7-d post initiation of treatment. Subjects will have blood drawn to assess for serological conversion to common enteric pathogens, and stool collected at 7- and 21-d . Subjects may also opt in for long-term follow-up at time of enrollment, which will assess for development of post-infectious functional bowel disorders. All subjects will complete a baseline assessment at 7-d visit, and those who opt for the additional follow-up will complete a series of web-based surveys at 3-, 6-, 9-, and 12-m post enrollment.