The world-wide distribution of traveller's diarrhoea is reflected in its many geographical synonyms - Delhi belly, the Aztec two-step, Turista, Malta dog, Rangoon runs, to name a few. Typically, the illness starts a few days after arrival at your destination and consists of diarrhoea without blood, nausea with some vomiting and perhaps a mild fever. The mainstay of treatment is adequate rehydration and rest, and the illness is usually self-limiting within a few days. Antibiotics to treat or prevent this common illness are not usually prescribed in anticipation of an infection. Exceptions to this rule are business travellers or others embarking on short trips (less than two to three weeks) for whom even a short period of illness would be disastrous, e.g. athletes attending international meetings.

The most important aspect of the treatment of diarrhoea is the replacement of fluids and salts that have been lost from the body. For most adults, non-carbonated, non- alcoholic drinks that do not contain large amounts of sugar are quite adequate. For adults with prolonged diarrhoea and for children, it is more important to use balanced weak salt solutions which contain a small amount of sugar that promotes absorption of the salts. These can be obtained in pre-packaged sachets of powder (e.g. Dioralyte, Rehidrat) that are convenient to carry and are dissolved in a fixed amount of sterile water. Dioralyte can also be bought in the UK as effervescent tablets, or as Dioralyte Relief sachets which contain pre-cooked rice powder. This has the advantage of returning the watery stools to normal more rapidly, as well as replacing the salts which have been lost in the diarrhoea. If pre-packaged mixtures are not available, a simple rehydration solution can be prepared by adding eight level teaspoonfuls of sugar or honey and half a teaspoon of salt to one litre of water (with flavouring to tempt small children).

Nausea, which frequently accompanies diarrhoea, can usually be overcome by taking small amounts of fluid as often as possible. For small children it may be necessary to give spoonfuls of fluid every few minutes for prolonged periods. If you or your child have severe vomiting which prevents any fluids being taken, medical attention must be sought immediately.

Anti-diarrhoeal drugs are not usually recommended and should rarely be given to children. Kaopectate is safe for children aged over two years but not very effective (Kaolin and morphine should not be carried). For adults, codeine phosphate, loperamide (Imodium or Arret) or diphenoxylate (Lomotil) are sometimes useful. These drugs should never be given to children and should not be used for bloody or prolonged diarrhoea. They are best reserved for occasional use to prevent accidents while travelling - for example before a prolonged rural bus trip. Prolonged use of these medications may prevent your body from eliminating the diarrhoea - causing organisms and toxins which may lead to constipation.

Preparations containing clioquinol are still widely available outside the UK, where it was previously sold under the trade name Enterovioform. These preparations are useless and should not be taken (they have been linked with severe side effects in some parts of the world). Other than rehydration solutions or the medications discussed in this article, I do not recommend purchasing medicines for diarrhoea from pharmacies or chemists.

Prevention

Travellers who wish to prevent diarrhoea should consult their medical adviser about preventative medication (a controversial issue within the profession) before travel. Liquid bismuth preparations (not an antibiotic) are effective but huge volumes need to be carried in luggage (very messy if broken), and bismuth tablets are difficult to obtain in the UK. Various groups of antibiotics may be used, including tetracyclines (e.g. doxycycline), sulphur containing antibiotics (e.g. Steptrotriad or cotrimoxazole, Septrin or Bactrim) and quinolone agents (e.g. ciprofloxacin, norfloxacin).

Prophylactic antibiotics are not recommended for the majority of travellers because of the limited duration of effectiveness and the possibility of side effects, including, paradoxically, diarrhoea. Vaccines are currently being developed to help prevent traveller's diarrhoea. The most promising vaccine is currently undergoing field trials in travellers and is looking safe and effective. This may be a good option for the future.

Self-treatment

Self-treatment with antibiotics for established diarrhoeal illness is usually inappropriate unless qualified medical attention is impossible to obtain. Travellers to remote areas may wish to carry a course of antibiotics for this eventuality.

If you have to treat yourself, obtain qualified medical investigation and help at the earliest opportunity. This is essential if symptoms do not settle after medication. Diarrhoea may be caused by other, more severe illnesses, including typhoid and malaria, and these would need specific treatment

Travellers who anticipate the need for self-treatment should take Richard Dawood's book Travellers Health: How to Stay Healthy Abroad (OUP).