Diarrhoea and vomiting
10th August 2018
Diarrhoea and vomiting (D&V) is as common a feature of foreign travel as airport delays and a regrettable tattoo.
Diarrhoea is defined as three or more unformed stools in a 24 hour period, often accompanied by at least one of the following: fever, nausea, vomiting, cramps, or bloody stools (dysentery)(1, 2). It is the most common health problem of overseas travellers affecting an estimated 20 to 60 percent of those who travel to high risk destinations of the world (1, 3-5). Approximately 20% of travellers are confined to bed for one or two days, 40% have to change their itinerary, and 1% are admitted to hospital (6). Vomiting is uncommon, and dysentery is infrequent (7). D&V typically occurs during the first week of arrival and is often self-limiting, lasting three to four days. Most episodes will last between one and seven days, with approximately 10% lasting for longer than one week, 5% lasting more than two weeks, and 1% lasting more than 30 days (8).
In summary, If you are travelling somewhere exotic, an episode of diarrhoea at some point in your adventure is almost a given, but, save for embarrassment and inconvenience, is rarely serious.
V&D is a global issue; the organisms that cause it ( e.g. Salmonella spp) are commonly reported worldwide, including in the UK. Other organisms such as Shigella spp. and Giardia lamblia for example are generally limited to lower-income countries that have inadequate sanitation facilities and a lack of access to clean water (1).
Where aetiology is known, bacteria are responsible for most cases and include Enterotoxigenic Escherichia coli (ETEC), Salmonella spp., Shigella spp., Campylobacter spp. (1) and Enterotoxigenic Bacteroides fragilis (9). Other organisms include viruses, such as norovirus, and protozoa (e.g. Cryptosporidium spp., Giardia lamblia).
40-70% of traveller’s diarrhoea cases never have a particular virus, bacteria, protozoa or fungi identified (10, 11)
Rates of diarrhoea are likely to correlate closely with the quality of local sanitation as such backpackers and remote workers have roughly double the incidence of diarrhoea compared with business travellers. (12) Destination and eating establishments are the most important factors (7) with diet, gender, age, host genetics, season of travel being additional factors (13, 14). Swimming pool-related outbreaks of illness are relatively infrequent, but have been linked to viruses, bacteria, protozoa and fungi (15, 16).
Regions (1, 10, 17, 18).
Western Europe, the United States, Canada, Australia, New Zealand and Japan. Seven percent or less of travellers are estimated to experience D&V in these areas
Southern Europe, Israel, South Africa, some parts of the Caribbean and the Pacific islands, with estimated incidence rates of between eight and 20 percent.
Most of Asia, the Middle East, Africa, and Latin America; more than 20 percent of travellers from a high-income country may experience D&V in these areas.
Several controlled trials have failed to demonstrate an impact of food and drink hygiene advice on rates of diarrhoea (19) However, the clear food-related source of most diarrhoeal pathogens means that the following are recommended but these measures do not offer full protection (26); general consensus is to continue to encourage travellers to adopt good hygiene practices whilst preparing to manage the symptoms of D&V.
- Boil water (21) or use of chlorine based tablets.(22)
- Cook food thoroughly (21)
- Peel fruit and vegetables. (21)
- Avoid ice, shellfish, and condiments on restaurant tables.
- Use a straw to drink from bottles.
- Avoiding salads and buffets where food may have been unrefrigerated for several hours.
- Hands should be washed after visiting the toilet, and always before preparing or eating food.
- Travellers should also practise good swimming pool hygiene by not swimming if they have diarrhoea, ensuring babies and infants are wearing suitable swimwear, and avoiding ingesting any pool water (16).
The expected dose for the diarrheagenic E. coli strains, the most common causes of D&V, is high in the level of one million bacteria or higher ( 23, 24 ) with the infections nearly always a result of ingestion of contaminated foods where food has been improperly handled allowing propagation of the pathogen to diarrhoea-causing levels. No matter how diligent the consumer’s personal hygiene ingestion of E.coli is only prevented if sanitation is adopted by the persons preparing the food
As such, D&V is difficult to prevent if you are not preparing your own food and drinks (25)
- Hand washing is most effective in prevention of enteric (relating to the intestines) infection caused by pathogens which occur at low inoculum doses. The most contagious enteric pathogens are noroviruses and Shigella strains (26, 27). Hand washing should be effective in reducing these highly communicable pathogens and should be actively encouraged in settings where these are likely to occur, e.g., enclosed, close proximity living environments such as camps, cruise-ship travel or remote work installations.
- While alcohol-based hand sanitizers often have anti-viral properties (28), there is only weak evidence that use of alcohol hand gel may reduce diarrhoea rates in travellers (29) but two recent systematic reviews estimated hand washing with soap reduces the risk of diarrhoeal illness by 30-40%. (30, 31) In another study (32) hand washing with soap and water was effective in removing norovirus from hands, while alcohol based hand sanitizers were not.
- In a retrospective survey of protective measures against D&V, regular use of alcohol hand sanitizers did not appear to offer any protection against diarrhoea in travellers (33). This is in contrast to the evidence that in developing regions the presence of soap in homes is associated with reduced diarrhoea rates in local populations living in unhygienic areas (34-36). Hygiene including hand washing undoubtedly has a greater effect in preventing diarrhoea in wilderness backpackers (37) who may have exposures more resembling endemic settings in the developing world than those seen with typical travellers staying in clean hotels.
- Hand washing with soap and water should be considered the standard while alcohol gel is suggested when hand-washing facilities or clean water are not available.
Although two meta-analyses suggest a marginal benefit of probiotics (e.g. natural yoghurt, cultured milk drinks) in prevention of diarrhoea, both suggest there is insufficient evidence (38-43) for recommendations. Probiotics are not recommended as a prophylaxis or treatment for diarrhoea. (44, 45).
Prophylactic antibiotics are not routinely recommended (46, 47); a routine use of chemoprophylaxis would create a large tablet burden and expose users to possible adverse effects of antibiotic therapy such as candidiasis and diarrhoea associated with Clostridium difficile. (48)
Prophylaxis should be considered for those with severe immune suppression, underlying intestinal disease (inflammatory bowel disease, ileostomies, short bowel syndrome), and other conditions such as sickle cell disease or diabetes where reduced oral intake may be particularly dangerous (49).
These patient groups may be unable to tolerate the clinical effects and dehydration associated with even mild diarrhoea, or the consequences of more invasive complications such as bacteraemia.
D&V is usually self-limiting (1, 48, 49). The aim of treatment of D&V is to avoid dehydration, reduce the severity and duration of symptoms and reduce the interruption to travel plans (50).
Adults without existing health problems, with mild to moderate symptoms and can tolerate simple foods can usually stay hydrated by continuing to drink and eat as normal (51). Consumption of small quantities of easily digestible foods are recommended to aid gut recovery in those with D&V (50). Breastfeeding should be continued for infants. Children receiving semisolid foods or solid foods should continue to receive their usual diet (21).
If the casualty is suffering from vomiting and is not able to keep food down, the casualty should consume only clean (boiled or bottled) water for 24 hours. Travellers should maintain adequate fluid intake to avoid dehydration. For a mild D&V illness oral fluids are often all that is necessary. (48)
For more severe symptoms or those prone to complications from dehydration, oral rehydration powders can be diluted into clean drinking water to remedy electrolyte (sugar/salt) imbalances. If oral rehydration powers are not available, a salt and sugar solution of six level teaspoons of sugar and one level teaspoon of salt to a litre of ‘safe’ water can be used (51).
Dehydration in adults is unusual, but is a concern for young children with diarrhoea. The elderly, pregnant women and those with pre-existing illness are also more susceptible to complications from dehydration (21).
The BRAT diet
The classic BRAT diet (limiting food intake to bananas, rice, applesauce, and toast) has been the standard teaching in the past because the diet was thought to be well tolerated by these patients. The goal of this therapy is to reduce the volume and frequency of stool.
While there is still some controversy about which types of food are best, many studies have shown that unrestricted diets do not worsen the course or symptoms of mild diarrhoea (52-54). For moderate to severe diarrhoea, fatty foods and foods high in simple sugars (including sweetened teas, juices, and soft drinks) should be avoided. Appropriate foods include lean meats, yogurts, fruits, and vegetables, as well as complex carbohydrates like rice, wheat, potatoes, bread, and cereals.
Individuals with ongoing symptoms depending on the history and clinical presentation may require further tests, such as; stool microscopy, stool culture, full blood count and/or biochemistry (55).
Medication - Symptomatic treatment
The most common symptomatic treatments for diarrhoea are antimotility agents (e.g. loperamide e.g “Immodium” and bismuth subsalicylate ( “Pepto Bismol”).
Loperamide can be considered for travellers when frequent diarrhoea is inconvenient, e.g. those travelling on long bus journeys, or for business meetings. However, it should not be used if the traveller has active inflammatory bowel disease (e.g. ulcerative colitis), a fever or bloody diarrhoea (8, 9, 15, 16, 21, 50, 51, 55-58).
For children under 12 loperamide is not recommended, parents should seek early medical advice if the child becomes unwell with diarrhoea. Rehydration is the main treatment for D&V in young children.
Bismuth subsalicylate can be recommended for mild diarrhoea and is helpful in reducing nausea. Bismuth subsalicylate preparations are available over the counter for use in adults and children over 16 years of age. However, loperamide has been shown to be more effective in controlling diarrhoea and cramping and works more quickly (49, 59)
Medication - Antibiotics
Symptomatic treatment is usually adequate and reduces antibiotic use. However, some travellers will benefit from rapid cessation of diarrhoea, particularly if they are in a remote area with limited access to sanitation facilities or healthcare.
Several systematic reviews of studies comparing antibiotics (including quinolones, azithromycin, and rifaximin) against placebo have shown consistent shortening of the duration of diarrhoea to about one and a half days from around three days. (60-62). Short courses (one to three days) of antibiotics are usually sufficient to effect a cure. (62)
Fluoroquinolones are often the drugs of choice when indicated (7). Ciprofloxacin (750mg as a single dose or 500mg twice daily for three days) is prescribed most commonly for travellers to Latin America and sub-Saharan Africa.
Fluoroquinolone resistant Campylobacter and Shigella are more common in some parts of South and Southeast Asia. For travellers to these areas azithromycin is an appropriate choice: 1,000mg single dose or 500mg once daily for three days (63, 64).
Rifaximin is also licensed for the treatment of travellers’ diarrhoea that is not associated with fever, blood in the stool or eight or more unformed stools in the previous 24 hours (64). Clinical data have shown that rifaximin is not effective in the treatment of invasive enteric pathogens that cross the gut wall such as Campylobacter, Salmonella and Shigella which typically produce dysentery-like diarrhoea (64). As travellers would have to carry a back-up drug in the event of these symptoms, the overall usefulness of rifaximin as a self-treatment option remains to be determined.
The combination of loperamide with an antibiotic in moderate travellers’ diarrhoea may lead to more rapid improvement compared with either treatment alone (21, 65).
Travellers should seek medical care if
- Vomiting does not improve over 24 hours.
- Diarrhoeal symptoms do not improve within three days (66).
- A fever of 38oc or more
- Blood and/or mucous in the stool
- Other worrying symptoms such as altered mental status, severe abdominal pain, jaundice or rash.
Medical care should be sought earlier for the elderly, children and other vulnerable travellers if they are not tolerating fluids or are showing signs of dehydration.
- D&V should be expected when travelling abroad, especially in high risk areas.
- The most vulnerable route to infection is ingestion of contaminated food.
- Where the individual has no control over food preparation, handwashing is the primary mechanism to prevent cross contamination with other travellers.
- Handwashing with soap and water is superior to alcohol gels. Alcohol gels should be used where soap and clean water is not available.
- D&V is usually self-limiting. If food is tolerated, continue a normal diet but with simple, digestible food.
- If food is not tolerated, consider clean water for 24 hours, supplemented with ORS if dehydration is predicted.
- Loperamide and bismuth subsalicylate can be considered to reduce symptoms.
- Consider medical treatment and antibiotics if:
- Vomiting does not improve over 24 hours.
- Diarrhoeal symptoms do not improve within three days (67).
- A fever of 38oC or more
- Blood and/or mucous in the stool
- Other worrying symptoms such as altered mental status, severe abdominal pain, jaundice or rash.
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