Unit 6 - Dysentery, Persistent Diarrhoea, and Diarrhoea Associated with
Medical Education: Teaching Medical Students about Diarrhoeal Diseases
Definition, etiology, and importance
features and diagnosis
Prevention PERSISTENT DIARRHOEA
Definition, etiology, and importance
History and examination
Fluid and electrolyte replacement
Drug therapy DIARRHOEA ASSOCIATED WITH OTHER ILLNESSES
Pneumonia and diarrhoea
Fever and diarrhoea EXERCISES
UNIT 6 - DYSENTERY, PERSISTENT DIARRHOEA, AND DIARRHOEA ASSOCIATED WITH OTHER ILLNESSES
Some children with diarrhoea are not adequately treated by the combination of
rehydration and diet therapy described in Treatment Plan A (see Unit 4). This
applies in particular to children with dysentery or persistent diarrhoea, or
whose illness is complicated by severe undernutrition or an infection outside
the intestinal tract. While such patients may need rehydration, they may also
require special approaches to feeding, antimicrobial therapy, or other
treatment. This unit describes the management of children with dysentery,
persistent diarrhoea, or other infections that may accompany or predispose to
diarrhoea. The management of children with diarrhoea and severe undernutrition
is considered in Unit 7.
Definition, etiology, and importance
Dysentery is defined as diarrhoea with visible blood in the stools. The most
important and most frequent cause of acute dysentery is Shigella,
especially S. flexneri and S. dysenteriae type 1. Other causes
include Campylobacter jejuni, especially in infants, and, less
frequently, Salmonella; dysentery caused by the latter agents is usually
not severe. Enteroinvasive Escherichia coli are closely related to
Shigella and may cause severe dysentery. However, infection with this
agent is uncommon. Entamoeba histolytica cause dysentery in older
children and adults, but rarely in children under 5 years of age.
Dysentery is an important cause of morbidity and mortality associated with
diarrhoea. About 15% of all diarrhoeal episodes in children under 5 years are
dysenteric, but these cause up to 25% of all diarrhoeal deaths. Dysentery is
especially severe in infants and in children who are undernourished, develop
clinically evident dehydration during their illness, or are not breast-fed. It
also has a more harmful effect on nutritional status than acute watery
diarrhoea. Dysentery occurs with increased frequency and severity in children
who have measles or have had measles in the preceding month, and diarrhoeal
episodes that begin with dysentery are more likely to become persistent than
those that start with watery stools.
Clinical features and diagnosis
The clinical diagnosis of dysentery is based solely on the presence of
visible blood in the diarrhoeal stool. The stool will also contain numerous pus
cells (polymorphonuclear leukocytes) which are visible with a microscope, and it
may have abundant mucus; these latter features suggest infection with a
bacterial agent that invades the intestinal mucosa (such as C.
jejuni or Shigella), but alone are not sufficient to diagnose
dysentery. In some episodes of shigellosis, the stool is initially watery,
becoming bloody after one or two days. This watery diarrhoea is sometimes severe
and may cause dehydration. Usually, however, numerous small bloody stools are
passed and dehydration does not occur. Patients with dysentery frequently have
fever, but sometimes the temperature is abnormally low, especially in the most
serious cases. Cramping abdominal pain and pain in the rectum during defecation,
or attempted defecation (tenesmus) are common; however, young children are
unable to describe these complaints.
A number of severe and potentially fatal complications can occur during
dysentery, especially when the cause is Shigella; they include:
intestinal perforation, toxic megacolon, rectal prolapse, convulsions (with or
without a high fever), septicemia, haemolytic-uraemic syndrome, and prolonged
hyponatraemia. A major complication of dysentery is weight loss and rapid
worsening of nutritional status. This is caused by anorexia, which may be
marked, the body's increased need for nutrients to fight infection and repair
damaged tissue, and the loss of serum protein from the damaged intestine (i.e.,
protein-losing enteropathy). Death from dysentery is usually caused by extensive
damage to the ileum and colon, complications of sepsis, secondary infection
(e.g., pneumonia), or severe undernutrition. Children convalescing from
dysentery are also at increased risk of death from other infections, owing
perhaps to their poor nutritional state or impaired immunity.
The cause of an episode of dysentery usually goes undetermined. Stool
culture, to detect pathogenic bacteria, is rarely possible. Moreover, at least
two days are required before results of a culture are available, whereas a
decision on antimicrobial therapy must be made immediately. Stool microscopy to
detect protozoa may also be unavailable or unreliable. Amoebiasis can only be
diagnosed with certainty when trophozoites of E. histolytica containing
red blood cells are seen in fresh stools or in mucus from rectal ulcerations
(obtained during proctoscopy). The detection of cysts alone is not
sufficient for a diagnosis of amoebiasis. Amoebiasis should be suspected
when a child with dysentery does not improve following appropriate antibiotic
therapy for shigellosis.
Children with dysentery should be presumed to have shigellosis and treated
accordingly. This is because Shigella cause about 60% of dysentery cases
seen at health facilities and nearly all cases of severe, life-threatening
disease. If microscopic examination of the stool is performed and trophozoites
of E. histolytica containing erythrocytes are seen, antiamoebic therapy
should also be given (see below). The four key components of the treatment of
dysentery (see Figure 6.1) are:
Early treatment of shigellosis with an appropriate antibiotic shortens the
duration of the illness and reduces the risk of serious complications and death;
however, such treatment is effective only when the Shigella are sensitive
to the antibiotic that is given. If treatment is delayed or an antibiotic is
given to which the Shigella are not sensitive, the bacteria may cause
extensive damage to the bowel and enter the general circulation causing
septicaemia, prostration, and sometimes septic shock. These complications occur
more frequently in children who are undernourished or in infants, and may be
As the antibiotic sensitivity of the infecting strain of Shigella is
not known for each case, it is important to use an oral antibiotic to which most
Shigella in the area are known to be sensitive. Co-trimoxazole is the
usual choice, but ampicillin is effective in some areas (see Annex 7). Although
treatment is recommended for five days, there should be a substantial
improvement after two days, i.e., less fever, pain, faecal blood, and loose
motions. If this does not occur, the antibiotic should be stopped and a
different one used; in many areas this would be nalidixic acid. Although other
bacteria, such as C. jejuni and Salmonella, can cause dysentery,
the disease is usually relatively mild and self-limited.
Young children with dysentery should
not be treated routinely for amoebiasis. Treatment should only be given
when E. histolytica trophozoites containing red blood cells are
identified in faeces or when bloody stools persist after consecutive treatment
with two antibiotics that are usually effective for Shigella. The
preferred treatment for amoebic dysentery is metronidazole (see Annex 7). If
dysentery is caused by E. histolytica an improvement will occur within
2-3 days of starting treatment.
Children with dysentery should be evaluated for signs of dehydration and
treated accordingly (see Units 3-5). All patients with dysentery should be
offered water and other drinks during their illness, especially if they have
Children with dysentery should continue to eat, so that nutritional damage
during the disease can be prevented or minimized. Feeding may be difficult,
however, because of anorexia. The general feeding guidelines in Treatment Plan A
(Units 4 and 7) should be followed: continue breast-feeding; give frequent small
meals at least six times a day; encourage the child to eat; choose energy and
nutrient-rich foods that the child prefers; and give one extra meal a day using
the same foods for at least two weeks after diarrhoea stops.
Most patients with dysentery show substantial improvement within two days
after beginning treatment with an effective antibiotic. These patients should
complete the five-day treatment, and do not require special follow-up. Other
patients should be followed closely, particularly children who do not show a
clear improvement within two days, and children known to be at high risk of
death or other complications. High-risk children (i.e. infants, the
undernourished, those not breast-fed, and any who have been dehydrated) should
be monitored frequently as outpatients or admitted to hospital. Dysentery
patients with severe undernutrition should be hospitalized routinely. Children
showing no improvement after the first two days of antibiotic treatment should
be given a different antibiotic, as described above.
The microorganisms that cause dysentery are spread by faecally-contaminated
hands, food, and water. The spread of shigellosis by hands is very efficient
because the number of Shigella required to cause disease is very small
(as few as 10-100 organisms). Important measures to prevent shigellosis are
described in greater detail in Unit 8.
Definition, etiology, and importance
Persistent diarrhoea is a diarrhoeal episode that lasts for 14 days or longer
(see Unit 1). Up to 20% of acute diarrhoeal episodes become persistent.
Persistent diarrhoea often causes nutritional status to deteriorate and is
associated with increased mortality. In some areas, it causes 30-50% of all
diarrhoea-associated deaths, and as many as 15% of episodes of persistent
diarrhoea result in death. There is no single microbial cause, although
enteroadherent E. coli may play a greater role than other agents;
Cryptosporidium may also be important in severely undernourished or
immunodeficient persons. A number of other pathogenic bacteria and protozoa are
found with nearly equal frequency in cases of acute and persistent diarrhoea,
but their role in causing this problem is unclear. Irrespective of its cause,
persistent diarrhoea is associated with extensive changes in the bowel mucosa,
especially flattening of the villi and reduced production of disaccharidase
enzymes; these cause reduced absorption of nutrients and may perpetuate the
illness after the original infectious cause has been eliminated.
A number of risk factors for persistent diarrhoea have been identified:
Undernutrition - this may delay the repair of damaged intestinal
epithelium, causing diarrhoea to be prolonged.
Recent introduction of animal milk or formula (or soya-based milk) - this
could reflect lactose intolerance, hypersensitivity to milk (or soya) protein,
bacterial contamination of the milk, or some other mechanism. Animal milk
appears to be an important factor in 30-40% of episodes of persistent diarrhoea.
Young age - most episodes occur in children under 18 months of age.
Immunological impairment - this is seen in undernourished children, during
or following measles or some other viral infections, and in patients with the
acquired immunodeficiency syndrome (AIDS).
Recent diarrhoea - this includes children who have experienced a recent
episode of acute diarrhoea or a previous episode of persistent diarrhoea.
Knowledge of these risk factors helps to
identify children who are most likely to develop persistent diarrhoea and, in
some instances, to guide treatment.
Persistent diarrhoea is largely a nutritional disease. It occurs more
frequently in children who are already undernourished and is itself an important
cause of undernutrition. A single episode of persistent diarrhoea can last 3-4
weeks or longer and cause dramatic weight loss, sometimes leading rapidly to
severe undernutrition, i.e. marasmus.
Weight loss during persistent diarrhoea is caused by reduced absorption of
all nutrients, but especially of fat and, in some children, lactose. Other
contributing factors include poor food intake, owing to anorexia or withholding
of food, or substituting dilute, low-energy foods. Patients are also likely to
be deficient in various vitamins and minerals: those of special importance
because of their role in the renewal and repair of the intestinal mucosa and/or
their role in normal immunological responses include folate, vitamin B12,
vitamin A, zinc, and iron.
The initial management of children with persistent diarrhoea is summarized in
Figure 6.1 and discussed below.
History and examination
These should cover the same areas as in cases of acute diarrhoea, but with
special attention to the following questions:
How many days has this episode of diarrhoea lasted?
What is the child being fed, breast milk or animal milk? If over 4-6 months
of age, is the type and amount of weaning food adequate? Is the food given in
small frequent servings? How is the child's appetite?
Was animal milk or formula (or soya formula) introduced recently? Does the
diarrhoea seem to be worse soon after animal milk or formula is given?
Has an antibiotic been given? If so, which one?
If this is a repeat visit, has the mother noted: any change since the last
visit in frequency of diarrhoea, blood in the stool, fever, or feeding problems?
Could she follow the last treatment advice given?
Is the child dehydrated?
What is the child's nutritional status? Has it declined during this
illness? (Measure and plot weight and height, if possible.)
Has the stool been bloody? Is it bloody now?
For all patients, it is important to observe whether the stool is bloody. The
use of other laboratory examinations will depend upon their availability. Some
of the most useful ones are summarized in Table 6.1.
Fluid and electrolyte replacement
The child's hydration status should be assessed as described in Unit 3. ORS
is satisfactory for replacing losses of water and salts in most children with
persistent diarrhoea; a few patients have severe glucose malabsorption (see Unit
5) and require intravenous fluid therapy. Some patients with persistent
diarrhoea develop dehydration and continue to lose stool rapidly after
rehydration; they should be hospitalized and may require treatment with
intravenous fluids until the rate of purging declines.
Proper feeding is the most important aspect of treatment for most children
with persistent diarrhoea. Many can be treated on an ambulatory basis with food
available in the home; however, some require specialized care in hospital. The
goals of nutritional therapy are to:
temporarily reduce the amount of animal milk (or lactose) in the diet;
provide a sufficient intake of energy, protein, vitamins, and minerals to
facilitate the repair process in the damaged gut mucosa and improve nutritional
avoid giving foods or drinks that may aggravate the diarrhoea; and
ensure that the child's food intake during convalescence is adequate to
correct any undernutrition and prevent its recurrence.
The general guidelines for feeding during
and after diarrhoea given in Treatment Plan A (see Unit 4) should be followed.
Some especially important or additional guidelines are shown in Figure 6.1 and
Children under 6 months of age or with evidence of dehydration should be rehydrated and referred to hospital for further management. They may require
special efforts to maintain hydration, replacement of animal milk with
lactose-free or artificial milk formula, laboratory studies to identify
pathogenic bacteria or protozoa in their faeces, or other specialized
For older children, the mother should be instructed to:
dilute any animal milk given to the child with an equal amount of water or
replace it with a fermented milk product, such as yoghurt. This reduces by half
the amount of lactose in the child's diet. In many cases, this step will cause
the diarrhoea to subside rapidly;
ensure a full energy intake for the child (i.e., about 110 kcal/kg/day) by
giving thick cereal with added vegetable oil; mix this with other foods, such as
well-cooked and mashed pulses, vegetables, and if possible, meat or fish. Avoid
low energy foods that are dilute or bulky. At least half of the child's energy
intake should come from foods other than milk or milk products;
avoid foods that are hyperosmolar (these are usually foods or drinks made
very sweet by the addition of sucrose, such as soft drinks or commercial fruit
drinks); these can make the diarrhoea worse;
give food in frequent small meals, at least six times a day; and
provide supplementary vitamins and minerals, in particular folate, vitamin
B12, vitamin A, zinc and iron, if possible.
Tell the mother to follow these instructions for five days and then bring
the child back to be checked:
if the diarrhoea has not stopped, refer the child to hospital for
specialized care, as described above;
if the diarrhoea has stopped, tell the mother to:
continue to give the same foods for the child's regular diet;
after one more week, gradually reintroduce the usual animal milk or formula
(if the child normally takes it) over several days; and
given an extra meal each day for at least one month. If the child is
undernourished, this regimen should be continued until the deficit of weight for
height is corrected. The child should also be seen at monthly intervals to
monitor growth (see Annex 3) and ensure that the feeding guidelines are being
Persistent diarrhoea patients with bloody stool or a stool culture positive
for Shigella should receive an antibiotic for shigellosis. If stool
culture yields another bacterial pathogen, e.g. enteropathogenic E. coli,
an oral antibiotic to which that agent is sensitive should be given. If
Giardia cysts, or trophozoites of either Giardia or E.
histolytica are seen in the faeces, a course of appropriate antiprotozoal
therapy should be given (see Annex 7). However, "blind" therapy with antibiotics
or antiprotozoal agents is not rewarding and should not be given.
Similarly, no "antidiarrhoeal" drug (including antimotility drugs, antisecretory
drugs and adsorbents) has any proven value in patients with persistent
diarrhoea; such drugs should not be given (see also Unit 4).
ASSOCIATED WITH OTHER ILLNESSES
Children with diarrhoea may also have other potentially serious illnesses,
especially undernutrition or other infections. Two nutritional disorders
associated with diarrhoea are considered in Units 3 and 7: vitamin A deficiency
and severe undernutrition. The following discussion concerns infections that may
be associated with diarrhoea.
The incidence of diarrhoea is increased during measles, during the 4 weeks
following illness, and possibly for up to 6 months after the measles episode.
Measles-associated diarrhoea is often severe and of longer than usual duration;
the risk of death is also substantially higher than with diarrhoea that is not
related to measles, and is probably even greater when children are also
undernourished. Where the incidence of measles is high, measles-associated
diarrhoea can account for one third, or more, of diarrhoea-associated deaths in
young children. Measles vaccination is therefore an important measure for
preventing both diarrhoeal episodes and diarrhoea-associated deaths, as well as
for preventing measles (see Unit 8).
The mechanisms by which measles predisposes to diarrhoea are not clear but
may include: (i) a direct effect of measles virus on the bowel epithelium, and
(ii) virus-induced immuno-suppression, which can last for several months after
an episode of measles and reduces the child's defenses against a variety of
pathogenic bacteria and protozoa. Measles-associated diarrhoea is frequently
bloody, suggesting that Shigella is an important causative agent.
The evaluation of children with diarrhoea should include an enquiry about
recent measles. Treatment of measles-associated diarrhoea should include:
- treatment of dehydration and dysentery, when present;
- adequate feeding (as described in Treatment Plan A, Figure 4.1);
- mouth care for patients with stomatitis, so that this does not interfere
with eating; and
- administration of a prophylactic dose of vitamin A (see Unit 7).
Pneumonia and diarrhoea
Diarrhoea with severe dehydration causes rapid breathing that may suggest a
diagnosis of pneumonia. However, in pneumonia the respiratory rate equals or
exceeds 40 per minute (50 per minute for infants aged 2-11 months), the child is
coughing, and intercostal retractions may be seen in the lower half of the
chest. In children with severe dehydration, the breathing pattern improves
rapidly when dehydration is corrected. If pneumonia is confirmed, an appropriate
antibiotic should be given.
Fever and diarrhoea
Fever is frequent in patients with diarrhoea. It is often present when
diarrhoea is caused by rotavirus or an invasive bacterium such as
Shigella, C. jejuni or Salmonella. Fever may also
accompany dehydration and disappear during rehydration.
Fever in a patient with diarrhoea may also be a sign of another infection
such as pneumonia, otitis media, or malaria. Diarrhoea patients with fever
should be examined for other infections and treated appropriately. However, it
is not appropriate to give antibiotics to patients with diarrhoea simply
because they have fever: a more specific indication is required, such as
pneumonia or bloody stools. If one is not found, the patient should be observed,
and the search for the cause of the fever continued, if it persists. Children
with fever (38° C or above) or a history of fever during the past five days and
who live in an area where there is falciparum malaria should be given an
antimalarial or managed according to the recommendations of the national malaria
control programme (see Figure 6.1).
A child with a temperature of 39° C or greater should be treated to reduce
the temperature. This may be done by giving paracetamol or, when fever is very
high, by sponging the head and abdomen with tepid water and fanning.
1. Ayaz, who is 2 years old, is brought to the health centre because he
has had bloody diarrhoea for three days. The health worker assesses Ayaz and
finds that he has no signs of dehydration and is neither febrile nor
malnourished. What should the health worker do for Ayaz? (There may be more than
one correct answer.)
2. Pedro is 9 months old. He was well
until three months ago when his mother stopped breast-feeding and began giving
him cow's milk with other food. Since then Pedro has had three episodes of
diarrhoea, the current one having begun 18 days ago. Pedro still takes cow's
milk but his mother has reduced his intake of solid food since the diarrhoea
began. There has been no blood in the stool. Pedro weighs 6 kg. What should the
health worker do?
- Treat Ayaz with metronidazole for possible amoebiasis, since he has no
- Refer Ayaz to the nearest hospital for a stool examination and culture.
- Teach the mother to continue feeding Ayaz an energy-rich diet.
- Treat Ayaz for five days with an antibiotic effective for Shigella
in the area.
- Advise the mother to bring Ayaz back if blood has not disappeared from the
stool after two days of treatment.
3. Maria, aged 16 months, began having
watery diarrhoea. After two days, her mother noted some blood in the stool and
brought her to the health centre. The doctor noted that Maria had a fever (39°
C) and saw that the stool contained blood. There was no evidence of
undernutrition. The doctor gave Maria co-trimoxazole but the mother came back
after two days saying Maria had not improved and the stool was still bloody.
What should the doctor do next?
- Prescribe a special lactose-free formula and have the mother give this
in place of the cow's milk.
- Give Pedro metronidazole for possible giardiasis.
- Advise the mother to dilute Pedro's milk with an equal amount of water and
to increase other energy-rich foods in his diet, e.g., by adding some vegetable
oil to his cooked cereal.
- Tell the mother to give Pedro sweetened fruit drinks or soft drinks, which
he likes, so that he receives enough fluid.
- Tell the mother to take Pedro to a hospital if he is not improving in two
4. Alam is 6 months old and takes only
formula milk. He has had watery diarrhoea for the past 14 days and during the
last 2-3 days his mother noted some blood in the stool. During the illness, Alam
has continued to take his formula. He has not had a fever. How should Alam be
treated? (There may be more than one correct answer.)
- Tell the mother to continue giving co-trimoxazole, since it is supposed
to be given for five days and she has given it for only two days.
- Send Maria to the hospital for a stool culture.
- Treat Maria with metronidazole for possible amoebiasis.
- Stop the co-trimoxazole and give another antibiotic to which most
Shigella in the area are sensitive, e.g. nalidixic acid.
- Give Maria erythromycin to treat a possible infection with C.
5. Chinta is 14 months old. She has
had a fever and watery diarrhoea for three days. Today some blood was seen in
the stool. When seen in the health centre, she is well nourished, drinks ORS
eagerly, and has reduced skin turgor. Chinta lives in an area where falciparum
malaria occurs. Which of the following steps are appropriate? (There may be more
than one correct answer.)
- Alam should be given an antibiotic effective for Shigella in the
- Alam's mother should start diluting his milk with an equal volume of
water. He should start to take cooked cereal with oil and other soft foods to
ensure an adequate intake of nutrients. If his diarrhoea has not stopped in five
days, he should be referred to hospital for further evaluation and treatment.
- Alam should be referred to hospital for special dietary care. This may
require the use of a lactose-free or soy-based formula.
- Alam's stool should be cultured and examined for amoeba and giardia.
- Alam should receive an antidiarrhoeal drug to help control his diarrhoea.
- Chinta should receive an antimalarial effective for falciparum malaria,
if that is recommended by the national malaria programme.
- Chinta should receive oral rehydration following Plan B for "some
- Chinta should receive treatment for shigellosis, using an antibiotic to
which Shigella in the area are usually sensitive.
- Chinta's mother should continue to give her a normal energy-rich diet,
feeding her frequent small meals.
- Chinta's mother should bring her back after two days of treatment to be
certain she is responding adequately.
1. C, D, E. Absence of fever is not unusual in children with shigellosis or
dysentery caused by other bacteria. Even in this situation, amoebiasis is very
2. C. The mother should bring Pedro back to the health centre after five
days; if his diarrhoea has not stopped, he should then be referred to hospital.
4. A, B. Answer D would be correct only if reliable laboratory facilities
were readily available, which is not usually the case.
5. A, B, C, D, E. The reason Chinta should return for follow-up is that she
had dysentery and was dehydrated when first