Travellers' Diarrhoea
Causes & Prevention
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 Travellers'
diarrhoea
(TD) is a condition characterised by a marked
increase in the frequency of unformed bowel
movements and is commonly accompanied by
abdominal cramps, urgency, nausea, bloating,
vomiting, fever, and malaise.
It occurs in up to a half of European
travellers who spend two or more weeks in
developing parts of the world and should
therefore be taken seriously.
Episodes of TD usually begin abruptly,
occur during travel or soon after returning
home, and are generally self-limiting. The
onset of TD is usually within the first
week of travel, but can occur at any time
during the visit and even after returning
home.
The most important determinant factor
is the destination of the traveller. High-risk
destinations include most of Latin America,
Africa, the Middle East, and Asia, where
attack rates of up to 50% have been reported.
TD is slightly more common in young
adults than in older people but attack rates
are similar in men and women. It is possible
for travellers to experience more than one
episode of TD during a single trip but rarely
is it life threatening.
 TD
is usually acquired by ingestion of
faecally contaminated food or water, or
both. Both cooked and uncooked foods may
be implicated if they have been improperly
handled. The place in which food is prepared
appears to be an important variable, with
private homes, hotels, restaurants, and
street vendors are listed in order of increasing
risk.
Particularly risky foods include
raw or undercooked meat, poultry, seafood,
raw fruits and vegetables. Tap water, ice,
and unpasteurized milk and dairy products
are also associated with increased risk
of TD. In the UK, we drink water straight
from the tap and rarely consider that the
water may be the source of disease but when
the cleanliness of a water supply is in
doubt, only adequately purified water should
be drunk.
 Safe
beverages include bottled carbonated
beverages (especially beverages like Coke
and Fanta), beer, wine, hot coffee or tea,
or water boiled and appropriately treated
with iodine.
TD typically results in four to five
(sometimes more) loose or watery stools
per day. The average duration of diarrhoea
is 3 or 4 days but about 10% of the cases
persist longer than a week and approximately
15% of cases experience vomiting, and up
to 10% have diarrhoea accompanied by fever
or bloody stools, or both.
 Most
food related illness is due either to
a change in the amount or type of food,
or an infection caused by eating contaminated
food. Infectious agents (Bacteria, Viruses
& Protozoans) are the primary cause
and people travelling from developed to
developing countries frequently experience
a rapid and dramatic change in the type
of organisms in their gastrointestinal tract.
These new organisms often include
potential enteric pathogens and those who
develop diarrhoea have usually ingested
sufficient virulent organisms to overcome
their individual defence mechanisms, resulting
in symptoms.
The organisms most commonly associated
with traveller's diarrhoea are; E.Coli,
Salmonella, Campylobacter, Shigella, Rotavirus
and Giardia.
 Prevention
of Travellers Diarrhoea
No vaccines are available
and none are expected to be available in
the near future that are effective against
TD.
The use of prophylactic antibiotics
is not recommended for travellers since
there is little evidence to show that they
are widely effective in preventing TD and
there are potential drawbacks which include
include allergic and other side effects
and the possibility of developing resistance.
However,
most evidence shows that meticulous
attention to hygiene during food and beverage
consumption can greatly decrease the likelihood
of developing TD. Many travellers, however,
encounter difficulty in observing these
restrictions.
 |
Some
useful precautions include:-
- Unless
you are sure of the purity of the
water supply, don't drink it. This
also applies to water used for ice-cubes
and for cleaning teeth.
- Water
from sealed lid bottles is usually
safe, as are hot tea and coffee,
fizzy drinks, beer and wine.
- Take
care with local cheeses and ice
cream. Boil unpasteurised milk before
use.
- Cook
meat thoroughly and eat while still
hot. Avoid leftovers.
- Fish
and shellfish may be hazardous even
if well cooked. Take local advice,
but avoid seafood if in doubt.
- Eat
only cooked vegetables and avoid
salads.
- Peel
all fruit, including tomatoes. Avoid
food exposed to flies.
- Wash
all dishes and cutlery in clean,
hot water.
- Wash
your hands thoroughly before eating
or handling food, and always after
using the toilet.
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Furthermore,
our intestinal flora are thought
to play an important role in protecting
us against infection and managing immunity.
They also provide specific enzymes needed
to digest particular substances in the
diet. Many digestive health problems
including TD can escalate as our fragile
intestinal flora is disturbed by the
environmental and dietary changes associated
with foreign travel.
 Travellers
can minimise these digestive health
risks by departing with a well balanced
and healthy intestinal flora and by
maintaining this protective shield throughout
thier travels. DTECTA Travel Support
is an advanced pro-biotic formulation
specifically developed for travellers
as an effective means to ensure a healthy
and well balanced intestinal flora by
strengthening the healthy balance of
friendly bacteria in the gut and enhancing
their protective capacity and by selectively
binding to harmful bacteria and flushing
it them out.
DTECTA Travel Support can be obtained
over the counter from many pharmacies
in the UK. The usual dosge is; two capsules
each day at mealtimes, starting one
week before departure and continuing
during travel abroad. |
 Treatment
of Travellers Diarrhoea
Travellers
with TD have two major complaints for which
they desire relief; abdominal cramps and
diarrhoea.
Oral
Rehydration Solution (ORS)
Most
cases of diarrhoea are self-limiting
and require only simple replacement of fluids
and salts lost in diarrhoeal stools. This
is best achieved by the use of oral rehydration
solution such as Dioralyte, Electolade,
Rehidrat, or similar, which is available
in sachets of powder at stores or pharmacies
in almost all countries and must be prepared
by adding the contents of a sachet to boiled
or treated water.
The instructions should be checked
carefully to ensure that the powder is added
to the correct volume of water. This solution
is appropriate for treating as well as preventing
dehydration and should be consumed or discarded
within 12 hours if held at room temperature
or 24 hours if kept refrigerated.
| If
sachets of ORS are unavailable or you
have run out, an emergency alternative
can be made up using eight teaspoons
of sugar and one teaspoon of salt added
to one litre of safe, drinkable water. |
Travellers
should be advised to avoid iced drinks
and non-carbonated bottled fluids made from
water of uncertain quality. Milk can aggravate
diarrhoea in some people and travellers
with diarrhoea should avoid it.
Antimotility
Agents
Such
as loperamide and codeine come in convenient
dosage forms and provide prompt symptomatic
but temporary relief of uncomplicated TD
by inhibiting intestinal movements.
 They
slow down the motility of the gut and increase
fluid absorption by normalising the transit
through the gut and restoring normal stools.
They also diminish diarrhoea and shorten
its duration thereby reducing fluid loss
at the same time.
Antimotility
agents relieve discomfort and social disruption
and are safe and effective for otherwise
healthy adults. They are best used when
sanitary arrangements are difficult such
as a long journey.
Self medication with antimotility agents
is appropriate following sudden onset of
increased bowel action with loose watery
stools in persons over 12 and under 75 years
of age who were previously in good health
and not suffering from any other serious
illness.
However, they should not be used by people
with high fever, with blood in the stools,
or if there is vomiting and dehydration.
They should be discontinued if symptoms
persist beyond 48 hours or they could make
the illness worse.
Medical
assistance
(if available) should always be sought if
any of the following occur:-
- There
is blood in the faeces
- There
is a fever
- The
sufferer becomes confused
- The
diarrhoea does not settle within 72 hours
However,
medical assistance is not always available
and the sufferer must decide whether or
not to be treated using available antibiotics.
 Antibiotic
Treatment
travellers
who develop severe and prolonged diarrhoea
especially if associated with nausea, vomiting,
abdominal cramps, fever, or blood in the
stools, would benefit greatly from antibiotic
treatment. Nausea and vomiting without diarrhoea
should not be treated with antibiotics.
The most likely antibiotic regimen
to be effective against enteric bacterial
infection is ciprofloxacin (500mg taken
twice a day), whilst metronidazole (800mg
taken three times a day) is usually effective
against protozoan infection. There is no
antibiotic treatment effective against viral
infection.
The biggest problem facing the sufferer
is being able to accurately diagnose the
cause which is virtually impossible without
medical training. Since the symptoms of
bacterial infections develop much more rapidly
than protozoan infections it is safe to
assume that a sudden onset is a bacterial
infection.
In this situation treatment should
consist of ciprofloxacin 500mg twice a day
but if no improvement is seen within three
or four days the sufferer should be switched
to metronidazole 800mg three times a day.
It must be stressed that this treatment
is to be undertaken in emergencies only
when there is no chance of getting immediate
medical assistance.
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Please
Note: The table below lists many of
the bugs that cause travellers diarrhoea
together with some of the common symptoms
but it should only be regarded as
a source of quick reference and not
as a definitive guide to the diagnosis
and treatment of travellers diarrhoea.
Accurate diagnosis even by a qualified
physician often requires lab culture
conformation.
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|
Table
of micro-organisms that cause travellers
diarrhoea and some examples of commonly
associated foods
|
Micro-
organism |
MEDIUM
|
Foods
|
Common
Symptoms
|
| FOOD |
WATER |
None
|
yes
|
no
|
heavily
spiced foods, strange, new diet |
Nausea
and mild diarrhoea usually lasting for
24 - 48 hours usually resolves without
specific treatment. |
| BACTERIA |
Bacillus
Cereus
|
yes
|
no
|
cooked
rice, cooked meats, vegetables |
1
- 5 hours predominantly vomiting or
8 - 16 hours predominantly diarrhoea.
|
Campylobacter
|
yes
|
yes
|
raw
milk, poultry |
Abdominal
pain, diarrhoea occasionally with blood,
malaise, vomiting is uncommon. Incubation
up to 11 days usually 2 - 5 days |
Cholera
|
yes
|
yes
|
Shellfish,
contaminated water |
Spread
by contaminated food or water, onset
is sudden but difficult to differentiate
from other types. Vomiting is frequent.
It improves as fluid replacement progresses.
Oral antibiotics reduce the length of
infection. |
Clostridia
|
yes
|
no
|
fish,
meats, vegetables, honey |
Diarrhoea
with abdominal pain, vomiting is rare.
Incubation is usually 12 - 18 hours.
Infection with Cl. Botulinum can be
fatal. |
Escherichia
Coli
|
yes
|
yes
|
salad,
raw vegetables, milk, cheese, undercooked
meat |
The
bacteria multiply in the small intestine
and produce toxins which give rise to
the symptoms which include passage of
profuse water stools. The condition
is self limiting and usually lasts for
48 hours. |
Listeria
|
yes
|
yes
|
cheese,
raw milk, coleslaw |
Diarrhoea
and abdominal pains are often accompanied
by conjunctivitis and a sore throat.
Rarely, in severe cases septicaemia
may develop. Particularly dangerous
in pregnant women as it can cause still
birth. |
Salmonella
(non typhoid)
|
yes
|
yes
|
dairy
products, salad, vegetables, eggs, meat,
shellfish |
Diarrhoea
containing mucus, abdominal pain, vomiting
and fever lasts about a week. Incubation
usually 12 - 36 hours. |
Shigella
|
yes
|
yes
|
potatoes,
eggs |
A
form of dysentery and responsible for
up to 15% of travellers diarrhoea. An
initial feverish phase with profuse
watery stools leading to a prolonged
illness with loose and frequent stools
containing blood and mucus. |
Staphylococcus
Aureus
|
yes
|
no
|
ham,
poultry, eggs, salad, cheese, cream,
ice-cream |
Nausea,
vomiting, abdominal pain, prostration,
dehydration, low temperature, sometimes
diarrhoea. Incubation usually 2 -4 hours. |
Typhoid
|
yes
|
yes
|
polluted
water, shellfish, contaminated milk
and milk products,
raw vegetables |
Symptoms
show after 7 days and include headache,
fever, abdominal pain, constipation
and diarrhoea. Usually fatal if left
untreated. |
Vibrio
Parahaemolyticus
|
yes
|
yes
|
raw
or undercooked shellfish, particularly
oysters |
Abdominal
pain, diarrhoea, occasionally nausea,
vomiting, fever and headache. Incubation
usually 12 - 24 hours. |
| VIRUSES |
Hepatitis
A
|
yes
|
yes
|
drinking
water, shellfish, raw fruit and vegetables |
The
virus is spread mainly by contaminated
drinking water. The main symptoms are
a flu like illness followed by loss
of appetite, nausea and vomiting, and
abdominal pain followed by jaundice.
Diarrhoea may or may not be present.
Development of chronic hepatitis is
rare with the A strain of the virus. |
Rotavirus
|
yes
|
yes
|
no
information |
Diarrhoea
can be severe due to invasion of gut
wall by the virus destroying the ability
to absorb fluids and reducing the levels
of digestive enzymes. |
| Norovirus
(Norwhalk) |
yes
|
yes
|
no
information |
The
norovirus is a poorly understood virus
and is very difficult to combat. Infection
is highly contagious and produces no
lasting immunity. It causes acute diarrhoea
and vomitting which is spread by droplets
and direct contact. Most episodes last
for 24 or 48 hours and are rarely serious
but can be very unpleasant. This virus
can be a particular problem on cruise
ships where it can spread very quickly
amonst the passengers and crew. |
| PROTOZOANS |
Cryptosporidium
spp.
|
yes
|
yes
|
raw
milk, raw sausages |
A
distant relative of the malaria parasite
the organism invades the gut wall and
causes an outflow of fluid that lasts
up to 10 days and longer. The only treatment
is rehydration therapy and the organism
is also resistant to chemical disinfection
including iodine. |
Entamoeba
histolytica
|
yes
|
yes
|
fruit,
vegetables |
Onset
of diarrhoea is gradual and there is
no fever which distinguishes it from
bacilliary dysentery. Diarrhoea contains
blood and mucus. |
Giardia
lamblia
|
yes
|
yes
|
fruit,
vegetables |
Profuse
watery diarrhoea is succeeded by a chronic
phase with bulky, foul smelling stools
which may persist for months. |
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