Diarrhoea - prevention and advice for travellers
Exam Tips
- In OSCEs, define severity clearly: mild = tolerable, moderate = interferes with activities, severe = incapacitating; all bloody diarrhoea counts as severe.
- Most common cause is bacterial, especially ETEC; Campylobacter is important in South/South-East Asia and may be fluoroquinolone-resistant.
- Always prioritise hydration and red-flag triage before prescribing symptom control.
- Loperamide is useful only in non-invasive disease; avoid in dysentery/fever.
- Persistent diarrhoea after travel (>14 days) should trigger stool testing for protozoa, especially Giardia.
- Common long-term exam association: post-infectious IBS after travellers' diarrhoea.
Definition
Travellers' diarrhoea is an acute gastrointestinal infection occurring during travel or within 10 days of return, typically defined as at least 3 unformed stools in 24 hours plus at least one additional symptom (for example abdominal cramps, nausea, fever, or blood in stool). It is usually acquired by faeco-oral transmission from contaminated food, water, or hands, and severity is graded as mild, moderate, or severe (all dysentery is severe).
Pathophysiology
Most cases are infectious and predominantly bacterial (especially enterotoxigenic/enteroaggregative E. coli), with viral and protozoal causes contributing smaller proportions. Non-invasive toxin-mediated organisms drive secretory watery diarrhoea via enterotoxin effects on enterocyte ion transport (increased chloride and water secretion), while invasive organisms (such as Campylobacter, Shigella, Salmonella) cause mucosal inflammation, fever, abdominal pain, and possible blood in stool. Protozoa (for example Giardia intestinalis) more often cause prolonged symptoms through mucosal irritation and malabsorption. The key systemic consequence is extracellular fluid loss leading to dehydration, electrolyte disturbance, and (in severe invasive disease) risk of bacteraemia/sepsis. For revision, review a faeco-oral transmission diagram and secretory-vs-inflammatory diarrhoea mechanism figure in your core microbiology/gastroenterology text.
Risk Factors
- Travel to high-risk destinations (many parts of Africa, Latin America, Middle East, and Asia)
- Exposure to unsafe food/water: street vendors, buffets, raw seafood, undercooked meat/poultry, unpeeled salads
- Backpacking, camping, adventure travel, and cruise travel (outbreak settings)
- Travel in hot/wet seasons
- Age under 6 years, older age, or frailty
- Immunosuppression (including HIV with low CD4 count)
- Inflammatory bowel disease
- Reduced gastric acid (proton pump inhibitor or H2-receptor antagonist use)
- Altered upper GI anatomy
- Visiting friends/relatives in endemic areas with reduced risk-avoidance behaviour
Clinical Features
Symptoms
- Loose/watery stools (>=3 in 24 hours)
- Abdominal cramps or pain
- Urgency
- Nausea and/or vomiting
- Fever
- Blood or mucus in stool (dysentery; severe disease)
- Bloating/flatulence and prolonged diarrhoea in protozoal infection
Signs
- Signs of dehydration: dry mucous membranes, thirst, reduced urine output
- Tachycardia, postural hypotension, delayed capillary refill in significant volume depletion
- Fever
- Abdominal tenderness (usually diffuse/crampy)
- Features of severe illness: confusion, oliguria, systemic toxicity, sepsis physiology
Investigations
Management
Lifestyle Modifications
- Pre-travel: risk-stratify by destination, season, itinerary, and host susceptibility
- Hand hygiene: frequent soap-and-water handwashing or alcohol gel when appropriate
- Food precautions in high-risk settings: eat food cooked fresh and served hot; avoid raw/undercooked meat/seafood, unpasteurised dairy, and foods left at room temperature
- Water precautions: sealed bottled/boiled/treated water; avoid ice unless made from safe water; use safe water for toothbrushing
- Peel fruit personally; avoid salads washed in unsafe water
- Carry oral rehydration salts and start early if diarrhoea develops
- Seek urgent medical care for blood in stool, high fever, severe dehydration, persistent vomiting, confusion, reduced urine output, or symptoms lasting beyond 1 week (earlier in children, older/frail adults, or immunocompromised people)
Pharmacological Treatment
Oral rehydration therapy
- Oral rehydration salts (for example Dioralyte): 1 sachet dissolved in 200 mL clean water; frequent small volumes, typically 200-400 mL after each loose stool in adults
First-line treatment; prioritise in children, older adults, frailty, and comorbidity. Continue normal feeding where possible.
Antimotility agent
- Loperamide (adult/age >=12 years): 4 mg initially, then 2 mg after each loose stool; maximum 16 mg in 24 hours
Short-term symptom control for non-bloody, afebrile diarrhoea. Avoid if blood in stool, high fever, suspected inflammatory/invasive colitis, acute ulcerative colitis flare, or suspected C. difficile; stop if abdominal distension/constipation develops.
Standby antibiotics for selected travellers (usually specialist/travel-clinic advice)
- Azithromycin: 500 mg once daily for 1-3 days (or 1 g single dose in selected adults)
- Ciprofloxacin: 500 mg twice daily for up to 3 days (regional resistance limits use, especially South/South-East Asia)
Reserve for moderate/severe disease, dysentery, or incapacitating symptoms where prompt care is difficult. Check contraindications/interactions and local resistance. Fluoroquinolones carry important MHRA safety warnings (tendon injury, neuropathy, CNS effects) and should be avoided when risks outweigh benefit.
Complications
- Dehydration and electrolyte disturbance
- Hospitalisation and interruption of travel plans
- Intestinal perforation (rare, invasive disease)
- Bacteraemia and sepsis
- Post-infectious irritable bowel syndrome
- Reactive arthritis (typically 1-4 weeks after infection)
- Guillain-Barre syndrome after Campylobacter infection (rare)
- Haemolytic-uraemic syndrome (rare, classically with Shigella dysenteriae type 1)
Prognosis
Overall prognosis is good: most episodes are self-limiting and resolve within about a week (many within a few days). Illness is more severe and clinically significant in young children, older/frail adults, and immunocompromised travellers; prolonged courses are more likely with protozoal infection or immunosuppression.
Sources & References
💊BNF Drug References(1)
- Tranexamic acid[management.pharmacological]
✅NICE Guidelines(1)
📖Textbook References(2)
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 434)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 434)[context]