Travelers’ diarrhea

The gut microbiota Antibiotic-associated diarrhea

It's not what you think...

Notice to globetrotters and travelers who’ve fallen victim to the dreaded “tourista”: this mostly benign infection which disrupts the gut microbiota¹ is actually called travelers’ diarrhea. A very common disease, it occurs in 10% to 40% of tourists² on a two-week trip, depending on the country visited and the characteristics of the traveler. It affects up to 60% of travelers in tropical or subtropical regions.³Although different in many ways from gastroenteritis, both diseases cause diarrhea.²

About this article

Created 02 August 2021

Updated 04 November 2021

What is travelers’ diarrhea?

Contrary to popular belief, travelers’ diarrhea is not caused by exotic foods poorly digested by unaccustomed stomachs. It is a real infection most frequently caused by bacteria (Escherichia coli, Salmonella, Shigella, Campylobacter).² It may also be caused by a parasite (Giardia, Cryptosporidium, etc.)² or a virus (norovirus, rotavirus).² The pathogen responsible for the diarrhea is identified in only 40%-60% of symptomatic travelers.⁴ The main source of the microorganisms involved are contaminated food (especially raw vegetables, undercooked meat or fish, unpeeled fruit, etc.) and contaminated water.⁵ It can also be transmitted through contact with other people when hygiene rules are not respected.⁵

40%-60% The pathogen responsible for the diarrhea is identified in only 40%-60% of symptomatic travelers

What is the microbiota’s role?

One of the gut microbiota’s roles is to prevent or limit the invasion of the intestine by pathogens (sidenote: Pathogens A pathogen is a microorganism that causes, or may cause, disease. Pirofski LA, Casadevall A. Q and A: What is a pathogen? A question that begs the point. BMC Biol. 2012 Jan 31;10:6. ) .⁶ Although common, the “tourista” is not without consequences. Regardless of the pathogen, diarrhea disrupts the balance of the gut microbiota at least temporarily, leading to dysbiosis (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232. ) .¹ This imbalance may have long-term consequences, including an increased risk of developing post-infectious⁷ irritable bowel syndrome, which occurs in 3%-17% of patients.² A research team recently showed that gut microbiota diversity was significantly lower in Swedish travelers who contracted a Campylobacter infection than in travelers who remained uninfected.⁸ Another research team found that diarrhea during travel was associated with a higher relative abundance in the gut of a specific bacteria (Prevotella copri) before departure and after return.⁹ Could travelers’ gut microbiota composition be used to predict the risk of developing diarrhea during the trip? Since there are still very few studies in this area, it remains to be confirmed.

What are the symptoms of traveler’s diarrhea?

The symptoms and duration vary depending on the cause⁴ (bacterial, parasitic or viral), but on average symptoms last 4-5 days without treatment.² In addition to frequent loose or watery stools (at least 3 per day),⁵ at least one of the following symptoms must be present: fever, nausea, vomiting, abdominal cramps or an urgent need to go to the bathroom.² The major risk is dehydration resulting from the loss of fluids through watery diarrhea. At-risk individuals (children, the elderly, or those with chronic conditions that weaken the immune system²) are more likely to be hospitalized.

Definition of travelers' diarrhea:

Mild

Tolerable diarrhea that does not interfere with planned activities.

Moderate

Diarrhea that restricts or interferes with planned activities.

Severe

Disabling diarrhea that results in complete inability to perform planned activities. Dysentery, i.e. diarrhea accompanied by blood and/or mucus, is considered a type of severe diarrhea.

Persistent

Diarrhea that lasts more than two weeks.

How to prevent and treat travelers’ diarrhea

The prevention of travelers’ diarrhea mainly involves hygiene measures such as frequent hand washing and food precautions.⁵ Ask your doctor or pharmacist for advice before traveling. Rehydration is key to treating travelers’ diarrhea:⁵ clean water (bottled water, etc.) or herbal teas drunk often and in small quantities. Any lightly sweetened and/or salted food is recommended (solid foods are not contraindicated).⁴ Antidiarrheal drugs help reduce the risk of dehydration and may be recommended in some cases.¹⁰ Antibiotics may also be necessary. However, antibiotics can lead to a reduction in the diversity of the gut microbiota, which thus loses its ability to act as a barrier against pathogens (sidenote: Pathogen A pathogen is a microorganism that causes, or may cause, disease. Pirofski LA, Casadevall A. Q and A: What is a pathogen? A question that begs the point. BMC Biol. 2012 Jan 31;10:6. ) . Moreover, antibiotic use can lead to the selection of antibiotic-resistant bacteria.¹¹ For this reason, they are only recommended for severe diarrhea, and in some cases for moderate diarrhea,¹⁰ under the supervision of a doctor. Probiotics may be useful as a preventive measure¹², and to limit the intensity and duration of symptoms.^13,14

This article is based on scientifically approved sources but is not a substitute for medical advice. If you experience symptoms, please consult your family doctor.

Sources

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^{3 Eckbo EJ, Yansouni CP, Pernica JM, et al. New Tools to Test Stool: Managing Travelers' Diarrhea in the Era of Molecular Diagnostics. Infect Dis Clin North Am. 2019 Mar;33(1):197-212.}

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^{9 Leo S, Lazarevic V, Gaïa N, et al. The intestinal microbiota predisposes to traveler's diarrhea and to the carriage of multidrug-resistant Enterobacteriaceae after traveling to tropical regions. Gut Microbes. 2019;10(5):631-641.}

^{10 Riddle MS, Connor BA, Beeching NJ, et al. Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report. J Travel Med. 2017 Apr 1;24(suppl_1):S57-S74.}

^{11 McDonald LC. Effects of short- and long-course antibiotics on the lower intestinal microbiome as they relate to traveller's diarrhea. J Travel Med. 2017 Apr 1;24(suppl_1):S35-S38.}

^{12 McFarland LV. Systematic review and meta-analysis of Saccharomyces boulardii in adult patients. World J Gastroenterol. 2010 May 14;16(18):2202-22.}

^{13 Dinleyici EC, Eren M, Ozen M, et al. Effectiveness and safety of Saccharomyces boulardii for acute infectious diarrhea. Expert Opin Biol Ther. 2012 Apr;12(4):395-410.}

^{14 Allen SJ, Martinez EG, Gregorio GV, et al. Probiotics for treating acute infectious diarrhoea. Cochrane Database Syst Rev. 2010 Nov 10;2010(11):CD003048.}

^{15 Pirofski LA, Casadevall A. Q and A: What is a pathogen? A question that begs the point. BMC Biol. 2012 Jan 31;10:6.}