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DIARRHOEA - a patient's guide
Dr Ali Goldkorn - Medical Researcher
What is it?
Diarrhoea is a very common symptom with many possible
causes. The term is used to describe an increase in frequency
of bowel motions, or increased stool liquidity, or sometimes
a sense of faecal urgency. A textbook definition of diarrhoea
is: "the passage of greater than 300 ml of liquid faeces
in 24 hours". However, this is not a very useful definition,
as stool quantity is hardly ever measured.
Common causes
As mentioned above, the causes of diarrhoea are myriad.
To determine which causes are more likely, a doctor will
need to know, amongst other things, a patient's normal bowel
habit, and how long the diarrhoea has been present. The
more common causes are listed below:
1. Infections
The most common causes of acute diarrhoea are infectious
agents (bacteria or viruses). In children, infectious diarrhoea
is an important cause of severe illness and accounts for
about 5 million deaths each year in children under the age
of 5. The problem is particularly common in developing countries,
where contributing factors include poor hygiene, ineffective
sewage systems, poor nutrition and lack of education. In
developed countries, acute infectious diarrhoea is common
in children attending creche or day-care centres.
"Food poisoning" is a term often used to describe infectious
diarrhoea. This occurs when bacteria are transmitted by
the "faecal-oral" route: usually someone who has the infection,
or is a carrier of the bacteria, gets it on his/her hands
and then handles food that is eaten by someone else.
A bacterium called Campylobacter jejuni is the most common
cause of food poisoning in New Zealand. Salmonella is another
common cause of food poisoning and is commonly associated
with improperly stored or undercooked chicken, beef or pork.
"Travellers' diarrhoea" is another infectious type of
diarrhoea. It is frequently caused by exposure to unpurified
water, in which case the bacteria most likely to be involved
include: Giardia, Cryptosporidium and Entamoeba Histolytica
(causing amoebic dysentery).
2. Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is another common cause
of diarrhoea and can be very difficult to treat. The symptoms
come on intermittently and typically occur over months or
years. Classically, a person with IBS will have alternating
constipation and diarrhoea, but the disease can also present
with abdominal pain as a predominant feature together with
intermittent constipation or diarrhoea.
There appear to be two underlying mechanisms that can
cause the symptoms of IBS:
1) abnormal gut motility (the normal peristaltic movements
of the intestine is impaired)
2) increased sensitivity to distention of the intestine.
The disease is four times as common in women than in men,
and is often triggered or exacerbated by emotional stress.
Treatment is aimed at altering gut motility; either by having
a high-fibre diet, or with various medications.
3. Medications
Many medications have diarrhoea as a possible side effect.
Antibiotics can cause diarrhoea, either as a direct effect
on the intestine, or by allowing overgrowth of normal gut
flora. Eating acidophyllus yogurt during a course of antibiotics
may prevent this problem.
Occasionally, a person taking a prolonged course of antibiotics
gets persistent diarrhoea even after stopping the antibiotics,
in which case they might be infected with a bacteria called
Clostridium Difficile, and may need to take another more
specific antibiotic to treat the diarrhoea.
Overuse of laxatives can also cause diarrhoea.
4. Inflammatory Bowel Disease
Crohn's Disease and Ulcerative Colitis are inflammatory
bowel diseases, which can cause chronic diarrhoea (often
severe and containing blood or mucous) as well as a variety
of other symptoms.
5. Other
"Overflow diarrhoea" can occur in people who are constipated
for a prolonged period of time and may in fact cause faecal
incontinence.
Emotional stress or anxiety can cause a diarrhoea, which
is usually mild and self-limiting.
HIV can cause diarrhoea through a variety of infections.
Diagnostic tests
In over 90% of patients with acute diarrhoea, the disease
will resolve within 5-7 days and specific diagnostic tests
are not really necessary.
However, if there are other associated symptoms, or if
the diarrhoea is persistent, the doctor may request certain
tests. These may include: a stool sample to look for bacteria
or parasites, blood tests, or in certain cases sigmoidoscopy
(a procedure that entails passing a "scope" through the
rectum to get a look at the intestine).
Treatment
1) Rehydration
Most adults with diarrhoea will not become dehydrated
provided they take in adequate fluids. Fluids containing
carbohydrates and electrolytes (e.g. fruit juice, energy
drinks, Gastrolyte) are preferable.
In more severe diarrhoea, especially in children, dehydration
can occur quickly and admission to hospital for intravenous
fluids may be necessary.
2) Diet
It is generally accepted that people with diarrhoea find
it more comfortable to rest the bowel by avoiding high-fibre
foods, fats, milk products, caffeine and alcohol, instead
taking in frequent small helpings of light meals and fluids.
3) Antidiarrhoeal agents
Drugs like Immodium, Lomotil and Diastop should be used
with caution. They are generally safe in cases of mild to
moderate diarrhoea and can improve one's comfort, but they
should be avoided in cases of bloody diarrhoea, or where
diarrhoea is associated with high fever and systemic illness.
4) Antibiotics
The overwhelming majority of patients with diarrhoea will
not need antibiotics. However, if there are symptoms or
signs of a systemic illness and/or the symptoms are persisting,
and particularly if bacteria are identified, then an antibiotic
may be appropriate.
Summary
There are many possible causes of diarrhoea. Most commonly,
it is a mild and self-limiting illness, but if symptoms
are severe or persistent, one should seek help from a doctor
as specific tests and/or treatment may be necessary.
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