Epidemiology and self-treatment of travelers' diarrhea in a large, prospective cohort of department of defense beneficiaries.

Background: Infectious diarrhea is a common problem among travelers. Expert guidelines recommend the prompt use of antibiotics for self-treatment of moderate or severe travelers' diarrhea (TD). There is limited data on whether travelers follow these self-treatment guidelines. We evaluated the risk factors associated with TD, the use of TD self-treatment, and the risk of irritable bowel syndrome (IBS) during travel.

Methods: Department of Defense beneficiaries traveling outside the United States for ≤6.5 months were enrolled in a prospective cohort study. Participants received pre- and post-travel surveys, and could opt into a travel illness diary and follow-up surveys for symptoms of IBS. Standard definitions were used to assess for TD and IBS. Suboptimal self-treatment was defined as the use of antibiotics (with or without antidiarrheal agents) for mild TD, or the use of antidiarrheals alone or no self-treatment in cases of moderate or severe TD.

Results: Twenty-four percent of participants (270/1,120) met the criteria for TD. The highest incidence was recorded in Africa [8.6 cases/100 person-weeks, 95% confidence interval (CI): 6.7-10.5]. Two hundred and twelve participants with TD provided information regarding severity and self-treatment: 89 (42%) had mild TD and 123 (58%) had moderate or severe TD. Moderate or severe TD was independently associated with suboptimal self-treatment [OR 10.4 (95% CI: 4.92-22.0)]. Time to last unformed stool did not differ between optimal and suboptimal self-treatment. IBS occurred in 4.5% (7/154) of TD cases and in 3.1% (16/516) of cases without TD (p = 0.39). Among TD cases, a lower incidence of IBS was noted in participants who took antibiotics [4.8% (5/105) vs 2.2% (1/46)] in those who did not, but the difference did not reach statistical significance (p = 0.60).

Conclusions: Our results suggest the underutilization of antibiotics in travelers with moderate or severe TD. Further studies are needed to systematically evaluate pre-travel instruction and traveler adherence to self-treatment guidelines, and the impact of suboptimal self-treatment on outcomes.