Travellers' Diarrhoea
Aetiology
This can be caused many different organisms such as E. coli, Shigella, Entamoeba histolytica, Salmonella, Campylobacter, Giardia, Cryptosporidia, Cyclospora and Vibrio cholerae. All these organisms are spread through the faecal/oral route.
Remember loose motions can also result from a change in diet including, for example, spicy or oily foods.
Prevention
This depends upon taking effective food and water precautions including water purification. Personal hygiene when eating and drinking is also important including hand washing prior to eating and using clean plates, cups and utensils.
Vaccination
- No licensed vaccines are available in the UK against travellers' diarrhoea
- Dukoral® (the oral cholera vaccine) may give some protection against travellers' diarrhoea specifically due to enterotoxigenic E. coli (ETEC) which produce a heat labile toxin (about 50% of ETEC strains). Widespread use of this vaccine is however not advised for travellers' diarrhoea. Chemoprophylaxis (see below) is generally preferred for those going to high risk countries when a a few days disruption to activities is unacceptable
Tablets to Prevent Travellers' Diarrhoea
A number of broad spectrum antibiotics have been show to reduce the incidence of travellers' diarrhoea by 70% to 90%. This is called chemoprophylaxis.
The normal antibiotic dose used for preventing travellers' diarrhoea
The preventive dose is half that used for treatment i.e. ciprofloxacin 250mg daily; doxycycline 100 mg daily; trimethoprim 100mg daily. Bismuth subsalicylate is an effective, non-antibiotic approach to prevent travellers' diarrhoea with an overall efficacy of about 60%. A tablet formulation is available (difficult to obtain in the UK) two tablets are taken 4 times daily (total of 1-2G) at meal times and on retiring. The liquid form (PeptoBismol or Boots Pepticalm) is bulky.
Recommendations for travellers
Chemoprophylaxis should not be used routinely. However it might be offered, for example, to a traveller who making a very short tour (3-5 days) when loss of even 12-24 hours would seriously impact on the success of the visit. Prophylaxis may also be helpful in those with pre-existing bowel problems such as colitis or irritable bowel syndrome where an attack of diarrhoea could seriously aggravate symptoms or cause relapse.
Remember antimicrobials may cause adverse drug reactions, which are occasionally severe and include diarrhoea. Ciprofloxacin occasionally causes confusion and hallucinations, doxycycline is contraindicated in pregnancy and young children.
Treatment
The priority in treatment is preventing dehydration especially in young children. Clear fluids such as diluted fruit juices or ideally specially prepared oral rehydrating solutions such as dioralyte (bought at the pharmacy) should be drunk liberally. All these preparations must be prepared with safe water. Antidiarrhoea agents such as loperamide (Imodium®) or diphenoxylate plus atropine (Lomotil®) should be used sparingly - they can help particularly with associated colicky pains. Overuse can cause rebound constipation and occasionally encourage other complications such as septicaemia.
Blood and mucous suggests campylobacter, shigella or amoebic infection. Marked vomiting, fever, pain, bleeding or dehydration usually requires hospital referral so that intravenous fluids can be administered.
While not necessary in most instances, if the diarrhoea is very frequent and continues for more than a few hours, use of the same antibiotics that are sometimes used for prevention can shorten the illness. They are effective against E.coli, shigella, salmonella and campylobacter. Amoebic dysentery requires the use of metronidazole.
The normal antibiotic dose used for treatment (for adults)
Ciprofloxacin 250mg, doxycycline 100 mg or trimethoprim 100mg (all taken twice a day). Azithromycin 500mg daily is an alternative and can be used in children or, if essential, during pregnancy. If used without medical supervision, prolonged courses are not normally necessary or desirable - treatment for 1 or 2 days is usually all that is required - and if the illness continues medical help should be sought.