Traveller's diarrhoea
Diarrhoea is the most common travel-related illness. The risk depends on the travel location and circumstances.
Symptoms
Traveller's diarrhoea is defined as the passage of three or more loose or liquid stools in a 24 hour period during travel or within 14 days of returning. It is more common in travellers to resource limited settings and can be accompanied by one or more symptoms like nausea, vomiting, abdominal pain or fever.
Travel related diarrhoea is inconvenient but often self-limited and usually not life threatening. Only a minority of travellers are confined to their accommodation and two out of five travellers need to adjust their travel plans due to diarrhoea. Hospital admission for rehydration or antibiotics is an exception and most common in risk groups such as children.
Classification of acute traveller's diarrhoea according to the Centre for Disease Control and Prevention (CDC):
- mild: tolerable, not distressing and does not interfere with planned activities
- moderate: distressing or interferes with planned activities
- severe: incapacitating or completely prevents planned activities, all dysentery is considered severe
- dysentery: passage of stools that contain gross blood admixed with stool and often accompanied by more severe constitutional symptoms including fever
Causative pathogens
Traveller's diarrhoea can be caused by bacterial, viral or protozoal pathogens.
Bacteria
This accounts for 80 to 90% of cases of traveller's diarrhoea and is therefore the most common cause. The incubation period is short from six hours to three days and the onset is sudden. Symptoms usually resolve after three to seven days.
The most frequently seen bacteria are:
- Escherichia coli (ETEC)
- Campylobacter jejuni
- Shigella spp.
- Salmonella spp.
- Aeromonas spp.
- Plesiomonas spp.
Cholera is rare in travellers.
“Food poisoning” can happen when infectious agents that release toxins are ingested, for example Clostridium perfringens or preformed toxins like in Staphylococcal food poisoning. Both vomiting and diarrhoea can be present and the symptoms usually resolve within 12 to 24 hours.
Viruses
Viruses account for 5 to 15% of cases of traveller's diarrhoea. They have a short incubation period from six hours to three days. The onset is sudden and symptoms often resolve after two to three days.
The most frequently seen viruses are:
- astrovirus
- norovirus
- rotavirus
Protozoa
Protozoa are free-living or parasitic one- celled organisms and account for roughly 10% of diagnoses of traveller's diarrhoea in long term travellers. The incubation time is longer compared to bacterial diarrhoea, often one to two weeks. It is slower to manifest and if left untreated they can sometimes persist for weeks to months.
Protozoa pathogens are:
- Giardia duodenalis: most common
- Entamoeba histolytica: relatively uncommon
- Cryptosporidium: relatively uncommon
- Dientamoeba fragilis: occasionally
- Cyclospora: seasonal and geographic risk (e.g., Guatemala, Haiti, Nepal, Peru)
Risk areas
Traveller's diarrhoea is most common in travellers to South-East Asia and Sub Sahara Africa (10-87%). Other areas with a relatively high incidence are Asia, the Middle East, Northern Africa, Mexico and Central- and South America. Northern and Western Europe, the United States, Canada, Australia, New Zeeland and Japan are low- risk areas (3-13%).
There might be a seasonal variation, for example In South Asia higher attack rates are reported during the hot months preceding the monsoon.
Locations where a large number of people lack plumbing or latrine access contamination of the environment with stool will be more frequent. Safe food storage can be difficult in areas with frequent electricity blackouts or poorly functioning refrigerators.
Risk for travellers
Poor hygiene practices in local restaurants and deficiencies in hygiene and sanitation infrastructure are likely the biggest source of traveller's diarrhoea. It occurs equally in male and females. and is seen more in young adult travellers than in older travellers. More than one episode can occur during a single trip and in general there is no immunity against future attacks. Visiting friends and relatives (VFR) travellers might have more exposure to foodborne and diarrheal illnesses because of the prolonged exposure, places they visit and the foods they eat. However some studies suggest that travellers who originate from high or intermediate risk regions for traveller's diarrhoea have lower rates of traveller's diarrhoea compared to other travellers.
Additional modifiable risk factors include:
- gastric acid inhibitors (e.g. proton pump inhibitor (PPI))
- recent antibiotic use
Risk factors for severe complications are:
- pregnancy
- very young or old age
- underlying chronic gastrointestinal diseases
- immunodeficiency
Prevention
Travellers should be advised on food and water hygiene but it can be difficult to adhere for those who cannot prepare their own food and drinks. Therefore travellers should always be prepared to manage symptoms of traveller's diarrhoea.
Handwashing:
- after visiting the toilet or changing diapers
- before, during and after preparing food
- before eating food
- after contact with animals
- if the hands are visibly dirty or greasy
Preferably water and soap is used. Soap is more effective than hand sanitizers at removing certain pathogens like norovirus, Cryptosporidium, and C. difficile, as well as chemicals. When this is not possible hand sanitizer containing more than 60% alcohol can be a useful alternative during travel.
Food, drink and hygiene precautions
Although travellers are often advised to ‘boil it, cook it, peel it or forget it’ in reality those precautions were never proven to be successful and have only limited preventive effects.
Poor hygiene practices in local restaurants and deficiencies in hygiene and sanitation infrastructure are large contributors to traveller's diarrhoea so it’s useful to keep this in mind when choosing eating establishments.
Drinking water and beverages
- avoid drinking tap water and ice
- drink bottled water: the cap should be opened in front of the traveller, be careful for rebottled beverages. Not all locally bottled mineral waters are safe.
- carbonated beverages are slightly safer due to the higher acidity and the difficulty to tamper with the crown cap
- boiled tea or coffee are alternatives if no bottled water is available, be careful no unboiled cold water is added since this is a common practice in certain countries
- brushing your teeth with tap water contains a certain risk but is most likely minimal
- avoid ingesting water while swimming
If there is no access to drinking water, the water should be cooked, filtered or disinfected before use.
Food
Travellers should be advised to avoid as much as possible:
- raw vegetables, grains and salades
- fruits that are not peeled at the spot
- raw or undercooked foods from animals: meat, poultry, eggs, seafood,…
- cooked food that has been stored at room temperature
- buffets at warm environmental temperatures, be cautious for contact with melting cooling ice since this is might not be potable water
- unpasteurized products: (coffee)milk, ice-cream, cheese, …
- ice-cream from street vendors (industrial produced ice-cream directly from an undamaged package conserved in a freezer is probably safe)
- restaurant with a lot of flies or other insect because they can contaminate the food
- food stalls have an increased risk compared to meals at a restaurant, although well cooked food that is consumed immediately can have a lower risk compared to some seemingly clean restaurants
Antibiotic chemoprophylaxis
Preventive use of antibiotics is not advised. Use of daily antibiotics has potential side effects, disrupts normal protective gastrointestinal flora that may be beneficial, and increases risk of colonization with multidrug resistant bacteria. These disadvantages are not outweighed by the prevention of a self-limited diarrheal illness.
Gastric acid inhibitors
Gastric acid is an important barrier against microbial pathogens. People who have a reduced production of gastric acid due to medication (e.g. proton pump inhibitors PPI), atrophic gastritis or gastric surgery are more vulnerable to acquire gastro-intestinal infections and should therefore be extra cautious. Reducing or interrupting PPI during their travel for a short period of time is often possible and should be discussed with the treating physician.
Antidiarrheal agents
There is insufficient data that the use of activated charcoal or probiotics would be beneficial in the prevention of traveller's diarrhoea and therefor their use should not be recommended.
Bismuth subsalicylate can reduce the incidence of TD by approximately fifty percent. It is not available as a single drug in Belgium (only in combination with other antibiotics). It needs to be taken four times a day and can cause blackening of the tongue and stool, constipation, nausea and in rare cases tinnitus. Studies have not established the safety of use for more than 3 weeks. It’s not recommended for children aged below the age of 12 years and pregnant woman due salicylate side effects. Because of the number of tablets required and the inconvenient dosing, bismuth subsalicylate is not commonly used as prophylaxis in traveller's diarrhoea.
Vaccination
Oral cholera vaccine (Dukoral®)
The oral cholera vaccine is developed for immunisation against cholera disease caused by Vibrio cholerae serogroups O1. It is not available in Belgium.
It contains antigens which are closely related to Enterotoxigenic Escherichia coli, one of the main causative agents of traveller's diarrhoea. This vaccine is only cross protective against strains who produce thermolabile toxins, and not against thermostable toxins.
Vaccination with the oral cholera vaccine will only give a partial (5 to 23%) and short protection against traveller's diarrhoea in general. For this reason the European Agency for the Evaluation of Medicinal Products (EMA) has not recognised this as an official indication.
Other vaccines
There are several vaccines available against organisms acquired through the consumption of contaminated food or water such as Salmonella Typhi, poliomyelitis and hepatitis A. These organisms do not cause the illness known as “traveller's diarrhoea“ but are still important to address as part of the overall travel health risk assessment.
Treatment
Read the treatments guidelines about travellers diarhoea.
Additional information
- Wikitropica: background information on diarrhoea in the tropics for medical professionals
CDC Yellow book: Traveler's diarrhea (CDC 2024)
References
- Statement on Traveller's diarrhea, Committee to advise on Tropical Medicine and Travel (CATMET, 2015)
- Lόpez-Vélez et al, Bacterial traveller's diarrhoea: A narrative review of literature published over the past 10 years. Travel Med Infect Dis. 2022 May-Jun;47:102293