Traveller’s diarrhea (TD) affects an estimated 20%-50% of international travelers, with high risk zones being South-East Asia, Sub-Saharan Africa, and South America. The Middle East, Oceania and Caribbean present a moderate risk.
Traveller’s diarrhea is defined as follows:-
Severe: At least 3 loose bowel movements within a 24hr period. May be accompanied by abdominal cramping, nausea and vomiting, fever and/or blood in the stools.
Moderate: 1-2 loose bowel movements with accompanying symptoms, or 3 or more loose bowel movements with no other symptoms.
Mild: 1-2 loose bowel movements without other symptoms and without disruption to daily activities.
About 50%-80% of traveller’s diarrhoea is caused by bacterial infection, with E.coli, shigella, campylobacter and salmonella being most common. 10%-20% of cases are viral. If diarrhoea persists for more than two weeks, and antibacterial therapy fails, protozoal parasite infection should be considered.
Some people are more susceptible than others, to traveller’s diarrhoea and its associated complications. High-risk groups include those with chronic underlying health issues, the immunocompromised, cancer patients, and those with bowel disease or abnormalities.
Although most cases of traveller’s diarrhoea resolve within 48 hours, 8%-15% remain symptomatic for more than a week, and chronic diarrhoea, lasting one month or more, develops in 2% of affected travellers.
Prevention strategies include avoidance measures, immunisation, and medication, however, advice regarding self-management via rehydration, medication and timely medical attention, is vital.
Generally, avoidance measures have involved recommendations for eating and drinking, such as avoiding untreated/unboiled tap water, raw foods, and fare from street vendors. Unfortunately, the vast majority of traveller’s find it very hard to stick to these guidelines, and 95% will discard them within days of leaving home. Furthermore, there is limited evidence as to whether these guidelines do reduce the risk of traveller’s diarrhoea. However, common sense regarding food and drink selection, and the use of antibacterial hand-wash before eating, would be wise.
Whilst there are vaccines available for diseases that induce symptoms of diarrhoea, including rotavirus, cholera, typhoid, hepatitis A and polio, these have little practical role in the prevention of traveller’s diarrhoea. The cholera vaccine may be considered for those who might be susceptible to complications from traveller’s diarrhoea, such as the immunocompromised or those with inflammatory bowel disease.
There is limited evidence about whether over-the-counter medications or probiotics offer protection from traveller’s diarrhoea.
Quinolone antibiotics are considered highly effective for the prevention of traveller’s diarrhoea, however, the risk of side-effects, and possibility of increasing antibiotic-resistance generally rule out this option, except in rare cases for individuals at extreme risk of infection.
Perhaps the most important measure is to equip travellers with knowledge and medication for appropriate self-treatment, in the event of infection. The first priority is preventing or treating dehydration, particularly in young children, pregnant women or older people. It is recommended that travellers purchase oral rehydration salts, available from pharmacies, an anti-motility medication such as loperamide, and an antibiotic before travel.
Oral rehydration plus loperamide is recommended for mild cases, however, if symptoms do not improve within 24hrs, or worsen, an antibiotic should be included in treatment – the most common are fluoroquinolones or azithromycin. The latter is preferred for use in South-East Asia, due to growing resistance to fluoroquinolones, and for use in pregnant women and young children under 8 years of age.
There are limited treatment options for young children, and the most important measure is oral rehydration. A powdered formulation of azithromycin may be used, if necessary. Anti-motility agents, such as loperamide, are contraindicted in small children, although may be used in children over 6 years of age, if strictly necessary, in order to control symptoms.
Traveller’s diarrhoea has the potential to cause long-term health issues – one example being irritable bowel syndrome in 3%-10% travellers who have experience traveller’s diarrhoea.