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 effective drinking
water
sterilization and ensuring food is uncontaminated or cooked thoroughly.
Personal hygiene when eating and drinking is also important including hand
washing prior to eating and using sterile plates, cups and utensils.
What to avoid
-
Water should only be drunk when you are
sure of its purity. Don't drink it without boiling, chemical disinfection
or using a reliable filter. This also applies to water used for making
ice cubes and cleaning teeth. Bottled water is usually safe, as are hot
tea and coffee, beer and wine.
-
Milk should be boiled unless you are sure
it has been pasteurised.
-
Cheeses and ice-cream are often made from
unpasteurised milk and when in doubt these should only be bought from larger
well established companies when quality can usually be assured.
-
Meat should be thoroughly cooked and eaten
hot whenever possible. Avoid leftovers.
-
Fish and shellfish can be hazardous at
certain times of year, even if well cooked. Take local advice about seafood,
but when in doubt it is best to avoid them.
-
Vegetables should only be eaten when thoroughly
cooked.
-
Green salads should be avoided.
-
Fruit should be peeled, including tomatoes.
-
Wash hands thoroughly before eating or
handling food, and always after using the toilet.
Vaccination
No vaccinations are currently available
in most countries for any of these infections although an oral cholera
vaccine is available in some countries and vaccines for E.Coli are under
development.
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
Half that used for treatment. e.g.
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 now available
- two tablets are taken 4 times daily at meal times and on retiring. (Two
weeks supply of the liquid form adds 5kg to the weight of a traveller's
luggage!)
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 contra-indicated
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 chemist) should be drunk liberally. All these
preparations must be prepared with sterile water. Anti-diarrhoea
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 require hospital referral so the intravenous fluids
can be administered.
While not necessary in most instances
of travellers' diarrhoea, 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
Ciprofloxacin 250mg, doxycycline 100
mg or trimethoprim 100mg (all taken twice a day). 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.
