Traveller’s Diarrhoea: Preventing It, and What to Do When It Happens
A large proportion of travellers to high-risk destinations develop diarrhoea, usually in the first week. Most cases are self-limiting, but it ruins trips and occasionally becomes serious, and the management has a few counterintuitive points.
What causes it
Mostly bacteria, with enterotoxigenic E. coli the single commonest, plus Campylobacter, Shigella and Salmonella. Viruses including norovirus and rotavirus account for a share, particularly on cruise ships. Parasites such as Giardia and Entamoeba are a smaller proportion and typically cause more prolonged illness.
The route is almost always food or water contaminated with faecal organisms.
Prevention: what works and what does not
The old rule “boil it, cook it, peel it, or forget it” is sound in principle, and studies have found that strict adherence is difficult and correlates less well with illness than expected, because contamination frequently occurs through hands, surfaces and serving rather than the food itself.
The measures with the best return:
- Hand hygiene before every meal. Soap and water where possible, alcohol gel otherwise. This is probably underweighted relative to food choice
- Bottled, boiled, or properly treated water, including for brushing teeth
- No ice, since it is usually made from tap water
- Avoid raw salads and pre-cut fruit from vendors
- Fruit you peel yourself
- Hot, freshly cooked food served steaming. Food that has sat at ambient temperature is the main risk, which is why a busy stall with high turnover is often safer than a quiet restaurant with a buffet
- Avoid buffets that have been standing
- Caution with dairy that may be unpasteurised, and with shellfish
- Avoid raw and undercooked meat and fish
Bismuth subsalicylate taken preventively reduces the risk meaningfully, though it requires frequent dosing, turns the tongue and stools black, and is not suitable for everyone, including those taking aspirin or anticoagulants, children, and pregnant women.
Prophylactic antibiotics are generally not recommended for routine travel, because of side effects, resistance, and the effect on gut flora. They may be considered for short critical trips or for people with significant underlying illness, as a medical decision.
Probiotics have mixed evidence for prevention.
Treatment
Rehydration is the treatment. Everything else is adjunct.
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- Oral rehydration solution is ideal, because it replaces electrolytes as well as water
- Where sachets are unavailable, a home solution of six level teaspoons of sugar and half a teaspoon of salt in one litre of safe water approximates it
- Bottled water, soups, diluted juice, coconut water
- Drink small amounts frequently rather than large volumes
- Judge adequacy by urine: passing pale urine every few hours means you are keeping up
Food: eat when you can tolerate it. Prolonged fasting does not help, and continuing to eat shortens recovery. Start with bland, salty, starchy foods. Avoid large amounts of dairy and very fatty food initially.
Loperamide reduces frequency and urgency, useful for travel days. Do not use it if there is fever or blood in the stool, because slowing the gut in invasive bacterial infection can prolong illness and in rare cases cause serious complications. Not for young children.
Bismuth subsalicylate is an alternative for mild symptoms.
Antibiotics are appropriate for moderate to severe illness: diarrhoea that is disabling, with fever, or with blood. A single dose or short course of azithromycin is commonly recommended, since fluoroquinolone resistance is high in South and Southeast Asia and Campylobacter is often resistant. Rifaximin is an option for non-invasive watery diarrhoea.
Many travel clinics provide a standby course to carry, with clear instructions on when to use it. Carrying it does not mean taking it for every loose stool.
Seek medical care for
- Blood or mucus in the stool
- High fever
- Severe abdominal pain
- Persistent vomiting preventing fluid intake
- Signs of significant dehydration: very little urine, dizziness on standing, dry mouth, lethargy
- Symptoms lasting beyond 72 hours without improvement
- Diarrhoea in an infant, an older adult, a pregnant woman, or anyone immunosuppressed
- Any diarrhoea with reduced consciousness
When it does not settle
Diarrhoea persisting beyond two weeks changes the differential.
- Giardia, typically causing bloating, foul-smelling stools, sulphurous burping and weight loss
- Amoebiasis, which can cause bloody diarrhoea and liver abscess
- Cyclospora, often with prolonged relapsing illness
- Post-infectious irritable bowel syndrome, which is common after an episode and can persist for months
- Temporary lactose intolerance after gut lining damage, which resolves over weeks
- Tropical sprue and other malabsorption syndromes, rarely
Stool testing is worthwhile at this point, and taking the travel history to the doctor matters, because these organisms are not routinely looked for without it.
For children
Dehydration develops faster and matters more.
- Oral rehydration solution, given in small frequent amounts, including by spoon or syringe if needed
- Continue breastfeeding
- Zinc supplementation for several days reduces duration and severity in children, and is recommended in many settings
- Do not give loperamide to young children
- Seek care early for reduced urine output, no tears, sunken eyes, lethargy or refusal to drink
The short version
Hand hygiene before eating is as important as what you eat, and food that is steaming hot from a busy stall beats a lukewarm buffet. Rehydration is the treatment, loperamide is for convenience and must be avoided with fever or blood, and an antibiotic is for moderate to severe illness rather than every loose stool. If it lasts beyond two weeks, get a stool test and mention where you travelled.