Traveller's diarrhoea: Treatment, symptoms, advice and help

Organism

Traveller's diarrhoea is an extremely common occurrence, affecting up to half of travellers to high risk areas such as Africa, Asia and South America. Even travellers to low risk areas such as Northern Europe, North America, Australia and New Zealand have a 5 to 10% risk of developing symptoms. In general traveller's diarrhoea is mild and short lived but can seriously disrupt holidays or business trips. A number of organisms can cause diarrhoea in travellers, although in up to 60% of cases no organism is identified, and it may be that diarrhoea is caused by a change in diet or medications. The commonest infective cause world-wide is Escherichia coli, a bacterium that produces a toxin which irritates the gut. Other bacterial causes include Shigella, Salmonella and Campylobacter, all of which can cause dysentery, that is diarrhoea with blood. A smaller proportion of cases overall are caused by parasites such as Giardia, Cryptosporidium and Amoebae, or viruses.

Mode of Transmission

Traveller's diarrhoea is transmitted by so-called faeco-oral spread, most commonly through swallowing contaminated water or food. It is most common in areas of poor sanitation where human or animal faeces enter the water supply. Traveller's diarrhoea can also be picked up from swimming pools or from sea water contaminated with sewage.

Regions Affected

The world can be divided intoareas of high, intermediate or low risk of traveller's diarrhoea. High risk areas include Africa, South America, Asia and the Middle East. Intermediate areas are southern Europe, Israel, Japan, South Africa and the Caribbean, while low risk areas are North America, Northern Europe, Australia and New Zealand. However there is a large degree of local variation, for example in some national parks in New Zealand there is a high risk of Giardia, and this organism is also found in the Moscow water supply. Local knowledge is invaluable.

Prevention

The most important preventative measure is education regarding simple measures to avoid traveller's diarrhoea. These include hand washing, drinking only boiled, bottled or treated water, avoiding ice in drinks, peeling all fruit and vegetables and avoiding undercooked foods and particular risky foods such as shellfish or unpasteurised dairy products.

Antibiotics such as Ciprofloxacin, Doxycycline or Co-trimoxazole can be taken to prevent traveller's diarrhoea and are extremely effective. However they are not recommended routinely as their use may lead to side effects and the development of bacterial resistance to these agents. They may be used exceptionally for cases where it would be devastating to develop diarrhoea, for example a national leader visiting a high risk area. Bismuth salts may also reduce the risk, but taste unpleasant, cause sickness and blackening of the tongue. Live yoghurt has been reported to be of benefit in some studies, but others dispute this.

Immunisation

Cholera is an uncommon cause of traveller's diarrhoea and the vaccine for this is minimally protective. There is a vaccine against typhoid, caused by Salmonella typhi but this does not give protection against the usual Salmonella strains causing traveller's diarrhoea.

Symptoms and Signs

Patients usually develop abrupt onset diarrhoea, sometimes with vomiting and often associated with crampy abdominal pains and fever. The diarrhoea may contain blood. Patients may become dehydrated, particularly if they are vomiting, causing sunken eyes, dry mouth and faintness. If they develop very severe dehydration (for example cholera) kidney failure may ensue.

Tests

The most important test is to examine samples of the diarrhoea for bacteria or parasites which may cause tra