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Traveller's diarrhoea: doing the Cancun Cancan

Norma Evans
RN BSc FPCert DipTravMed
Independent Travel Health and Immunisations Nurse Specialist

Travellers' diarrhoea is defined as the passage of three or more unformed stools each day either during or shortly after travel, or any number of such stools when accompanied by fever, abdominal cramps or vomiting.(1) Although more than 30% of travellers to developing countries can expect to have a bout of diarrhoea, most of these episodes will be mild and self-limiting with a mean duration of approximately four days.(2) 

Epidemiology
When assessing the risk of acquiring travellers' diarr-hoea the world can be divided into high-, intermediate- and low-risk areas. These are shown in the map from the Centers for Disease Control and Prevention, Atlanta (see Figure 1).

[[nip34_fig1_34]]

In high-risk destinations, which include South America, Africa, some parts of the Middle East and most of Asia, up to 50% of travellers will develop diarrhoea, while 20% of travellers to intermediate-risk areas, such as Israel, Southern Europe, South Africa and some of the Caribbean islands can be expected to develop gastrointestinal infection.(3) It is estimated that a traveller leaving a low-risk area such as the UK in order to stay in a high-risk area probably has a 40% likelihood of infection.(4)

Risk factors
Susceptibility to travellers' diarrhoea is general and as no immunity is conferred the traveller may experience repeated bouts. Although any traveller can develop diarrhoeal illness some groups of people are at increased risk. These groups include:

  • Those who for social or business reasons have little choice regarding where they eat or what they eat.
  • Those on medications such as proton pump inhibitors, which reduce the gastric acid barrier.
  • Those who stay in areas with low standards of sanitation and hygiene.

Some groups (eg, the immunocompromised, the elderly or the very young) are also more vulnerable to the effects of a bout of diarrhoea, and prevention advice is particularly important for these.
Although factors such as the availability of clean drinking water and freshly cooked hot food will influence the chances of getting diarrhoea, the behaviour and lifestyle of the traveller will also impact on the level of risk. Travelling with a high budget does not mean that the traveller will not contract diarrhoea, but it can help to minimise risk factors. Illness can, for example, be transmitted by swimming in contaminated water as well as by drinking it. Therefore those who use well chlorinated pools will be at less risk than those who bathe in freshwater pools and rivers.

Illness
Travellers' diarrhoea can be caused by various microorganisms including bacteria, viruses and protozoa. Transmission is usually faeco-oral and once ingested the infecting organism can damage the gut or interfere with the normal gut processes.
Although person-to-person transmission of diarrhoeal illness is rare it does occur with viruses such as rotavirus and the Norwalk virus. These viruses are highly contagious. Norwalk, which causes severe vomiting, has been the cause of several large outbreaks on cruise ships and is very difficult to eradicate.
The clinical presentation of the illness varies according to the organism causing the diarrhoea. Some of these are shown in Table 1. Organisms such as Shigellosis require ingestion of only a small amount of infected matter to cause illness, while others such as Vibrio cholerae require a larger ingestion. The most common cause of travellers' diarrhoea is enterotoxinogenic Escherichia coli (ETEC), which is responsible for about 50% of cases.(5)

[[nip34_table1_35]]

This illness is common within the first few weeks of arrival in a country, as later on it is possible to develop some immunity to local serotypes. It is useful to highlight this point to travellers who say: "I eat what the locals do." This frequently used practice can have pitfalls as the locals may well have developed some immunity, and so it is seldom a good idea to use them as a guide to safe eating.
Incubation periods and the frequency and type of diarrhoea vary, and diagnosis is often made presumptively from the symptoms. Where there is doubt regarding the cause, stool culture or microscopy may be required for confirmation.

Prevention
High standards of personal hygiene and food and water hygiene are key elements in the prevention of travellers' diarrhoea:

  • All drinking water and water used for teeth cleaning should be either bottled or have been purified by boiling, filtering or chemical disinfection. Organisms in ice cubes are not destroyed by alcohol and therefore ice cubes should be avoided.
  • Human excreta is often used as fertiliser in resource poor countries and all fruit and vegetables should be peeled. Raw vegetables and salads are best avoided.
  • Crockery and cutlery can harbour cysts and should be scrupulously cleaned. If ensuring cleanliness is not possible, food should be wrapped in a clean napkin and held in clean hands.
  • Some foods such as ice cream, shellfish and seafood are particularly risky and are best avoided. As bacteria needs moisture, dry foods (bread, biscuits) are regarded as safer than moist foods (sauces).
  • Hot food should be fresh and served piping hot. Avoid lukewarm or reheated food as bacteria can grow at extremely fast rates in warm temperatures. Special care should be taken when food is served from a buffet. The cold food may have been warming up while the hot food may have cooled. Either will be an ideal breeding ground for the bugs that cause illness.
  • Hand hygiene is essential. Hand-sanitising gels are useful where washing facilities are poor or nonexistent.
  • Use only pasteurised milk or boil milk before use. Only eat cheese made from pasteurised milk.
  • Food should at all times be protected from sources of contamination such as flies, unwashed hands or unclean surfaces.

Every pretravel consultation should include comprehensive advice on avoiding diarrhoea given both verbally and in written format. Useful patient information sheets are available from many sources including the National Travel Health Network and Centre (www.nathnac.org) and these are very helpful when advising on diarrhoea prevention.
It is accepted, however, that the circumstances encountered when travelling often make it difficult for the individual to comply with prevention advice and it is sometimes necessary to make compromises. Some travellers will do all that they can to avoid illness and will adjust their diets and lifestyle to comply with safety rules. Others are keen to experience all that travel has to offer, even at the risk of getting diarrhoea, and they will take chances in order to freely experience the gastronomic culture of the countries they visit. It should be recognised that having received advice the travellers may then make their own choices regarding how they will comply with prevention measures. Health professionals need to respect these decisions and be prepared to discuss food and water hygiene practices that will allow a measure of safety while still allowing the traveller the freedom to enjoy all aspects of the trip. 
It is also worth remembering that many bouts of "holiday tummy" are in fact the result of a change of diet, overindulgence in alcohol or even too much sun, so not all events can be attributed to contaminated food and water.
Some travellers request broad-spectrum antibiotics as prophylaxis against travellers' diarrhoea. These are effective as they reduce the chances of contracting travellers' diarrhoea by 70-90%.6 However, most travellers would not warrant such preventive measures although antibiotic use may be considered for those travellers who have a pre-existing medical condition, eg, colitis, or for people such as business travellers, who would be severely disrupted by a few days of illness. The decision of whether antibiotics are to be prescribed should be made after a full consultation that includes assessment of the individual circumstances of the traveller.
The use of bismuth subsalicylate (Pepto-Bismol; Procter & Gamble) has also been demonstrated to be beneficial in preventing diarrhoea especially when it is used in conjunction with good food and water hygiene precautions. Although less effective than antibiotics, this approach is favoured by many travellers. The product is not licensed for the prevention of travellers' diarr-hoea and those who wish to take it would need to buy it over the counter as it is not prescribed.(7) The dose is two tablets four times a day. Although the liquid format can be taken, carrying such large amounts of liquid medication can present practical difficulties, especially with the recent more stringent security precautions at airports.

Treatment
The first very important element in the treatment of travellers' diarrhoea is rehydration. Large amounts of fluid are rapidly lost during an episode of diarrhoea and immediate replacement is vital, especially for the very young or those who have pre-existing medical conditions. Ready prepared rehydration salt sachets can be bought from pharmacies. Alternatively a rehydration measuring spoon with a small end for salt and a larger end for sugar can be used to mix the correct amount in a glass of sterile water. A rule of thumb for adult fluid replacement is a  glass of fluid every hour and after every bowel movement.(4)
Careful fluid replacement is very important for children. Those aged two and under will require 50-100 ml of fluid after each loose stool while children aged two to 10 years should take 100-200 ml.7 Breastfed infants should continue to feed throughout the illness with extra fluids offered if necessary.(8)
Rehydration should begin as soon as diarrhoea starts. If the patient is vomiting, small sips of water will be better tolerated than large gulps, and the vomiting is likely to decrease as fluid is replaced.
Watching for signs of dehydration in children or the elderly is vital, but even a healthy adult can become clouded in judgment if weakened by diarrhoea and dehydration. It is important for companions to watch out for warning signs such as dry tongue, cracked lips, reduced urine output or a weak rapid pulse.
A normal diet should be eaten during illness if this is possible. If not then food should be reintroduced as soon as possible for travellers of all ages. Initially bland foods such as dry toast, potatoes or bananas are preferable to fatty foods, but when stools become formed again a full diet can be resumed.
Antimotility agents such as loperamide have a place in the treatment regime as they can decrease stool frequency and reduce the duration of the illness.(9) They are useful when a long journey is to be undertaken for example, but they should always be used with caution as they can lead to constipation. They are not suitable for infants or children and they should never be used if the diarrhoea is bloodstained.

When to get help
Although most episodes of travellers' diarrhoea will resolve without treatment, it is nevertheless important to recognise when medical help should be sought:

  • When a temperature of over 38ºC occurs or if a fever lasts longer than 48 hours as this may indicate septicaemia.
  • When the patient is elderly, very young or has pre-existing illness and is showing signs of dehydration.
  • When diarrhoea persists for longer than four days.
  • When the patient cannot tolerate oral fluid replacement.
  • When blood or blood and mucus is seen in the stools.

Summary
Although travellers' diarrhoea is frequently mild and self-limiting, it is nevertheless commonplace, distressing and it can, in some cases, lead to severe complications. The extensive range of organisms known to cause diarrhoea has increased during recent years and it seems reasonable to assume that there are other, as yet unidentified, organisms also causing illness.
Advice on prevention is a fundamental part of every pretravel consultation. Some travellers will, however, make lifestyle choices that put them at risk. These choices should not be judged harshly, because compliance with all diarrhoea avoidance advice may remove a great deal of the pleasurable elements that a traveller anticipates from a trip. In such cases it is often best to discuss compromises so that the traveller can make informed choices regarding the preventive measures they do find acceptable.
Even those who carefully comply with all aspects of prevention advice may still be unfortunate enough to become ill. All travellers need to be equipped with basic information regarding rehydration and the use of antimotility agents, and all should know when to seek help. Whenever possible, advice should be reinforced by written information - when travellers' diarrhoea strikes, recalling verbal advice given some time ago would be too great a challenge for anyone!

References:

  1. 1. Ostrosky-Zeichner L, Erricsson C. Travelers' diarrhoea. In: Zuckerman J, editor. Principles and practice of travel medicine. Chichester: Wiley; 2001.
  2. Farthing M. Travellers' diarrhoea. In: Lockie C, Walker E, Calvert L, editors. Travel medicine and migrant health. Edinburgh; Churchill Livingstone: 2000.
  3. General Practice Notebook. Diarrhoea (travellers). Available from: http://www.gpnotebook.com/cache/-2026569723.htm
  4. Behrens R, Barer M. Diarrhoea and intestinal infections. In: Dawood R, editor. Travellers health: how to stay healthy abroad. 4th ed. New York: Oxford University Press; 2002.
  5. Travax. Travellers' diarrhoea. Available from: http://www.travax.scot.nhs.uk
  6. Fit for Travel. Travellers' diarrhoea. Available from:http://www.fitfortravel.scot.nhs.uk
  7. Prodigy Knowledge Guidance. Travellers' diarrhoea - preparing for a trip. Available from: http://www.cks.library.nhs.uk/gastroenteritis/scenario/travellers_diarrh...
  8. National Travel Health Network and Centre. Travellers' diarrhoea. Travellers information sheet. Available from: http://www.nathnac.org/travel/misc/travellers_dir.htm
  9.  De Bruyn G, Hahn S, Borwick A. Antibiotic treatment for travellers' diarrhoea. Cochrane Database Syst Rev 2000;
    3:CD002242.