Biweekly prophylactic doxycycline for travelers' diarrhea

Area of Science:

• Infectious Diseases
• Tropical Medicine
• Pharmacology

Background:

• Travelers' diarrhea is a common illness affecting individuals visiting foreign countries.
• Enterotoxigenic Escherichia coli (ETEC) is a primary cause of travelers' diarrhea.
• Preventive strategies, including antibiotic prophylaxis, are crucial for mitigating this condition.

Purpose of the Study:

• To evaluate the efficacy of biweekly oral doxycycline in preventing travelers' diarrhea.
• To assess the impact of doxycycline on the incidence of diarrhea caused by specific pathogens.

Main Methods:

• A double-blind, placebo-controlled study involving 46 Peace Corps volunteers in Honduras.
• Participants received either 100 mg of doxycycline or a placebo biweekly for three weeks, followed by a three-week observation period.
• Stool samples were analyzed to identify causative pathogens, with a focus on ETEC resistance patterns.

Main Results:

• No significant difference in overall travelers' diarrhea incidence during the three-week treatment phase.
• A statistically significant reduction in travelers' diarrhea episodes was observed in the doxycycline group during weeks two, three, and four.
• Enterotoxigenic Escherichia coli (ETEC) was the most frequently identified pathogen, with 62% of isolates showing doxycycline resistance.

Conclusions:

• Biweekly oral doxycycline demonstrated marginal effectiveness in preventing travelers' diarrhea.
• The antibiotic's efficacy was compromised by the high prevalence of doxycycline-resistant ETEC.
• Doxycycline prophylaxis did not prevent diarrhea caused by resistant ETEC strains, highlighting the need for alternative prevention strategies.