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Health Centres - Travellers' diarrhoea
Written by Dr Charlie Easmon, specialist adviser in travel medicine
Causes of travellers' diarrhoeaThe most common cause of holiday or travellers' diarrhoea is the different types of virus and bacteria at the destination.
The local drinking water in particular is an obvious source of risk in many places and should, therefore, be completely avoided. Replace it with water from previously unopened bottles for drinking as well as for cleaning teeth and making ice for drinks.
Approximately 40 per cent of all cases of travellers' diarrhoea are due to infections with ETEC (enterotoxin-forming Escherichia coli bacteria). It is also possible to be infected with other and more specific and unpleasant bacteria and parasites, such as cholera, typhoid fever, paratyphoid fever, Salmonella, Clostridia, Yersinia, Shigella, Bacillus cereus, amoebae and Giardia lamblia. Such infections will typically require medical treatment and possibly antibiotics, whereas the common, but troublesome travellers' diarrhoea is self-limiting and passes within a week.
Incidence
The risk of suffering from diarrhoea is very high and estimates vary from 30-80 per cent of travellers! It rises among other things with the exotic nature of the destination, the climate (particularly in the tropics) and poor general and personal hygiene, but stomach infections can occur anywhere in the world, and unpleasant bacteria also flourish in the UK (for example Salmonella, Campylobacter and Listeria).
Factors affecting infection and general prevention
Travellers' diarrhoea is typically due to one or more of the following factors:
- food that has gone off
- contaminated food and drink
- poisonous substances (toxins).
Many problems can be avoided by knowing and understanding the mechanisms of infection and spread, which include:
- infection from faeces to hand and then to mouth. A typical example of this is if a chef or waiter is a little slapdash in going to the toilet, uses little toilet paper and does not bother washing his hands. He then warmly shakes the guest's hand before the latter picks up a chicken leg and puts his teeth into it without washing his hands. Or what about the change you put in your pocket, using the same hand to put a sweet or something else in your mouth? This is a typical way of contracting Shigella dysentery. Prevention consists of washing the hands frequently, particularly before eating.
- from faeces to food or drink and then to mouth. For example, the butcher, chef and farmer, etc have the same lack of hygiene as described above, but in this case transfer the infection directly to food or drink. And the farmer no doubt may also use cheap human manure rather than expensive commercial fertiliser for his salad crops. In this infection mechanism, prevention consists of adequate heat treatment of food/drinks. Remember that ice cubes may also be infected.
- toxins (poisonous substances) that occur for example in botulism and when rice dishes are left standing (go cold). In the latter case, the cause is a toxin from Bacillus cereus, and toxins of this kind cannot be removed by reheating or renewed boiling.
The familiar old slogan: 'Cook it, boil it, peel it, - or leave it' is still the most important basic rule to follow.
A good many stomach infections can be avoided by taking some simple precautions.
- Always wash your hands twice with soap before using them to put anything at all in your mouth and dry your hands by air or a clean towel. Wet hands still carry a significant risk of infection. In the field you can always take a plastic bottle of soapy water or special antiseptic wipes with you.
- Avoid the local drinking water, dairy products and ice cream in destinations where there is a high risk.
- Eat only fresh foods that have been directly and sufficiently heat-treated.
- Salads washed in the local drinking water are obviously a risk - watch out for the dressing as well.
- Shellfish and fish that have been on display in the sun all day or have lived in the water from a sewage outlet are obviously not the things to eat.
- Food stalls on the street are exciting, but are not advised owing to their doubtful hygiene
- Take a look inside the kitchen at the place where you are intending to eat. If it is swarming with flies, which spread more infection than all other insects put together, or if there is leftover food in the pots, and the chef/waiter has visible boils or infected sores, find somewhere else to eat.
- Products from home distilleries can be a real health disaster.
- Avoid pouring ice-cold drinks down into a warm stomach (does not cause infection, but stomach cramps).
Prevention with medicines
. Vaccination against hepatitis A, either with active vaccine or with gammaglobulin, is always to be recommended. Although hepatitis A does not cause travellers' diarrhoea, the infection is typically transmitted with infected food/drinks. In Europe, freeze-dried lactic acid bacteria capsules are popular, but there is no proof that they work.
Treatment of travellers' diarrhoea
As mentioned, the majority of cases will calm down within five to eight days and do not require any drug treatment. On the other hand, the following can be recommended:
- drink plenty of fluids (at least 3-4 litres a day and aim to replace everything that is put out!) – more in the case of fever, vomiting and diarrhoea in the tropics. Fruit juice, diluted fresh juice (1:4), cola, broth/soup are also useful as it is also important to take in salts. A certain amount of sugar is in order, but must not be overdone. Dairy products, coffee and alcohol should be avoided.
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