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Bronchiolitis
Bronchitis
Croup
Influenza
Pertussis
Pneumonia
The authors
DR JO HARRISON,
consultant respiratory physician,
department of respiratory
medicine, Royal Children’s
Hospital, Melbourne, Victoria.
ACUTE RESPIRATORY
infections in children
Background
ACUTE respiratory infections are a
major cause of morbidity and mortality
worldwide. They are responsible for
one in five deaths in children under the
age of five years, with pneumonia the
cause in 90% of these deaths.
Childhood mortality from respiratory infections in developed countries
such as Australia is fortunately rare,
but these diseases remain a significant cause of morbidity. They are the
most common infections experienced
ASSOCIATE PROFESSOR
JOHN MASSIE,
consultant respiratory physician,
department of respiratory
medicine, Royal Children’s
Hospital, Melbourne, Victoria.
Table 1: Classification of acute respiratory infections
by healthy children and result in significant numbers of medical visits and
hospital admissions, particularly in the
preschool age group.
Based on the site of infection, acute
respiratory infections may be classified
as acute upper or acute lower respiratory infections (table 1). This article
reviews the most common types of
acute respiratory infections, their clinical
features, diagnoses and management.
cont’d next page
Acute upper respiratory infections
Acute lower respiratory infections
Nasopharyngitis
Laryngotracheobronchitis (croup)*
Pharyngotonsillitis
Bronchitis
Otitis media
Bronchiolitis
Epiglottitis
Pneumonia
Laryngotracheobronchitis (croup)*
Influenza*
Influenza*
Pertussis**
*Croup and influenza involve both upper and lower airways
**Pertussis starts as a coryzal illness, but the main recognisable clinical feature of cough is
lower airway in origin
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8 May 2009 | Australian Doctor |
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HOW TO TREAT Acute respiratory infections in children
Bronchiolitis
Epidemiology
BRONCHIOLITIS is the
most common cause of
acute lower respiratory
infection in children during
the first year of life. It is the
most common cause of
admission to hospital in this
age group, accounting for
more than 50% of all such
admissions in Australia. The
peak incidence of bronchiolitis occurs in infants aged
2-6 months, with more than
80% of cases occurring in
babies under 12 months of
age.
The most common infectious agent responsible for
bronchiolitis is respiratory
syncitial virus (RSV), and
the epidemiology of bronchiolitis is mainly determined by the epidemiology
of this viral infection. RSV
infections are most common
in winter and spring in temperate climates, with up to
75% of all cases identified
between July and September
in temperate regions of Australia. In tropical and subtropical climates, epidemics
tend to occur in the rainy
season.
There is virtually no protection to young infants
from transplacental antibodies, or from breast milk. Furthermore, active RSV infection does not result in lasting
immunity, so recurrent RSV
infection is common and can
occur within the same
season.
Almost all children experience at least one RSV infection during the first two
years of life, although only
10% of those infected
develop acute bronchiolitis.
Most babies with bronchiolitis can be managed at
home, with about 1%
requiring admission to hospital.
Factors that make hospital admission more likely
include young age (particularly babies under three
months of age), prematurity
(particularly gestation less
than 32 weeks), congenital
cardiac disease and chronic
lung disease. Indigenous children in Australia are also
more likely to require admission, with rates of hospitalisation almost eight times
those of non-Indigenous children.
Spread of RSV occurs via
large droplets transferred to
the individuals’ hands,
where the virus can survive
for up to one hour. The virus
is then transferred to the
eyes or nose, resulting in
infection. RSV can also survive on hard surfaces for as
long as 30 hours. The incubation period of RSV is
between three and eight
days.
Pathogenesis
RSV invades the epithelial
cells of the respiratory tract
and spreads from cell to cell
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| Australian Doctor | 8 May 2009
Active RSV
infection does not
result in lasting
immunity, so
recurrent RSV
infection is
common.
Figure 1. Infant with acute viral bronchiolitis. Note hyperinflation, prominent perihilar bronchial
markings and some patchy airspace shadowing. Note: for infants with a clear clinical presentation,
a chest X-ray is not required for the diagnosis of bronchiolitis.
portation factors.
• Clinical assessment.
Clinical features that
should prompt urgent paediatric review of an infant
with suspected bronchiolitis
are listed in table 2. The
stage of illness (disease trajectory) is an important consideration in determining
which patients require
review, as babies in the early
stages of infection are at risk
of further deterioration,
whereas those who have
been symptomatic for five
days or more are most likely
to be improving.
Specialist management
Table 2: Clinical
features of severe
bronchiolitis
• Poor feeding (fluid intake
<50% of normal in the
preceding 24 hours, poor
urine output)
• Lethargy
• Apnoea
• Respiratory rate > 70
breaths per minute
• Nasal flaring or grunting
• Severe chest wall
recession
• Cyanosis
• Oxygen saturation <92%
by inducing cell fusion and
the formation of syncytia.
Ciliated epithelial cells are
destroyed and there is necrosis of the bronchiole epithelia, along with oedema of
the bronchiole walls and
increased secretion of mucus.
Signs and symptoms
Bronchiolitis presents most
frequently in infants aged 36 months, with breathing
difficulties, cough (may be
dry/irritating or moist), poor
feeding and fever. In very
young babies (typically those
under 1-2 months), the only
symptom may be apnoea.
Examination
findings
include:
• Tachypnoea.
• Increased work of breathing (intercostal and subcostal recession, tracheal
tug and sometimes expiratory grunting).
• Chest hyperinflation.
• Widespread
crackles
and/or wheeze heard on
auscultation.
These symptoms are usually preceded by an initial
coryzal phase lasting for 2-3
days.
Assessment and
diagnosis
The diagnosis of bronchiolitis is clinical, based on the
typical symptoms and examination findings described
above. Although fever is
common, the finding of a
high fever (temperatures
>40°C) is unusual and
should prompt careful consideration of alternative
diagnoses.
In hospital settings the
clinical diagnosis is usually
confirmed by identifying
RSV, or another respiratory
virus, in a respiratory
sample (usually nasopharyngeal aspirate). Immunofluorescent (IF) antibody methods
allow
rapid
identification of the virus
responsible and enable
infants with the virus to be
isolated, which is important
for infection control. IF
results are available within
a few hours and this method
has excellent specificity and
good sensitivity. The presence of the virus is then usually confirmed by viral culture, but this result is not
available for up to one
week.
Chest X-rays are not usually helpful for diagnosing
bronchiolitis (they usually
demonstrate a range of findings from hyperinflation,
atelectasis and patchy infiltrates) (see figure 1). The
main role is if a differential
diagnosis is suspected clinically, for example, because
of localised chest signs
(pneumonia) or a heart
murmur (cardiac disease).
GP therapy
Mild bronchiolitis can usually be managed at home
with appropriate advice and
reassurance to the parents.
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Parents or carers should be
given information on how
to recognise signs of deterioration in their infant and be
strongly advised to bring
them back for reassessment
if it occurs.
Additional therapies such
as bronchodilators, systemic
and inhaled corticosteroids,
nebulised adrenaline or
antibiotics have been well
shown to have no role in the
treatment of the infant with
bronchiolitis. In some cases,
bronchodilators can exacerbate ventilation/perfusion
mismatch and make infants
more hypoxic. This is
important to consider, as it
can be tempting to treat the
wheeze with bronchodilators ‘in case’ the diagnosis
is asthma.
Children over 12 months
may also have bronchiolitis
and not respond to bronchodilators, although by this
age a trial of a bronchodilator, especially in an atopic
child or one with a family
history of asthma, is reasonable. However, we would
recommend a trial dose
(administered through a
spacer) be given first under
observation to assess
response.
When to refer
A small number of babies
with bronchiolitis will
require admission to hospital. In deciding which babies
require admission, several
factors are taken into consideration, including:
• Age.
• Presence of underlying
comorbidities such as congenital heart disease.
• Premature birth or chronic
lung disease.
• Socioeconomic factors.
• Geographical and trans-
Treatment of RSV infection
in hospitalised infants is
largely supportive and generally includes supplemental
oxygen and fluid replacement either by nasogastric
tube or intravenously. Nasal
suction is often helpful, but
other therapies, including
physiotherapy, are not.
Early introduction of continuous positive airway pressure (CPAP) for infants with
severe respiratory distress
often obviates the need for
intubation and mechanical
ventilation.
RSV prophylaxis
Palivizumab is a human
recombinant monoclonal
RSV antibody that is administered as a monthly injection during the RSV season.
Although it does reduce hospitalisation and admission
rates to ICU in high-risk
groups (for example, former
preterm infants, those with
chronic lung disease or
acyanotic congenital cardiac
disease), it has not been
shown to reduce the need
for mechanical ventilation.
Consequently, its efficacy
and cost-effectiveness have
been challenged and it is
only available for babies in
the high-risk groups in their
first RSV season.
Prognosis
The prognosis for most
babies who develop acute
bronchiolitis in Australia is
very good and overall mortality rates are very low.
Fifty per cent of previously
healthy infants with bronchiolitis will be symptom
free after 14 days.
About 10%, however,
develop a post-bronchiolitic
syndrome with symptoms of
cough and wheeze that persist for several weeks and
can recur intermittently for
several years, usually in
association with subsequent
viral infections.
Most eventually recover
completely, so that by the
age of 13 years there is no
increase in wheezing
episodes. RSV bronchiolitis
in infancy is not a risk
factor for asthma in adulthood.
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HOW TO TREAT Acute respiratory infections in children
Bronchitis
ACUTE bronchitis is a
common clinical syndrome in
children, caused by inflammation of the trachea, bronchi
and bronchioles, usually in
association with a viral respiratory tract infection. Acute
bronchitis is rarely bacterial
in otherwise healthy children.
Symptoms of acute bronchitis usually include cough that
produces phlegm and may be
associated with retrosternal
pain during deep breathing or
coughing. Generally the clinical course is self-limiting, with
complete healing and full
return to function typically
seen within 10-14 days after
symptom onset.
Epidemiology
The annual incidence of bronchitis in children in the developed world is 20-30%, with
an equal incidence in males
and females. Acute bronchitis
occurs most commonly in
children younger than two
years, with a second peak seen
in children aged 9-15 years.
tussis, whereas Streptococcus pneumoniae, nontypeable
Haemophilus
influenzae and Moraxella
catarrhalis may be significant pathogens in preschoolers.
The cause of the cough in
acute bronchitis is multifactorial but involves mucosal
injury, epithelial damage and
the release of inflammatory
cytokines as well as transient
bronchial obstruction and
hyper-responsiveness in a
proportion of patients.
Signs and symptoms
Acute bronchitis
usually begins
with symptoms
similar to those
of the common
cold.
of acute bronchitis, with
bacteria implicated in fewer
than 10% of cases. The
organism responsible is not
usually identified in clinical
practice, but when viruses
are identified they are usually one of the common respiratory viruses such as
influenza A or B, parainfluenza or RSV.
Bacteria that can cause
acute bronchitis in otherwise
healthy school-age children
include Mycoplasma pneumoniae and Bordetella per-
Pathogenesis
Respiratory viruses are by
far the most common cause
Acute bronchitis usually
begins with symptoms similar to those of the common
cold, such as coryza, malaise,
chills, low-grade fever, sore
throat, and back and muscle
pain. The initial watery nasal
discharge becomes thicker
and discoloured after several
days and is accompanied by
a cough. Purulent nasal discharge is common with viral
respiratory pathogens and,
by itself, does not imply an
underlying bacterial infection.
The cough is initially dry
and harsh but then loosens
and becomes productive.
Children younger than five
years rarely expectorate, and
sputum may be seen in vomitus. Parents frequently note
a rattling sound in the chest.
Examination findings are
frequently normal although
the pharynx may be injected.
Auscultation typically reveals
clear lung fields, although
scattered crackles or wheezing can sometimes be heard.
Recurrent episodes of
acute or chronic bronchitis
are unusual and should
prompt consideration of
alternative diagnoses such as
asthma or suppurative lung
disease (cystic fibrosis,
immunodeficiency, ciliary
dyskinesia).
GP therapy
The vast majority of children
with acute bronchitis can be
managed as outpatients
unless their illness is complicated by severe underlying
disease. Treatment is
directed at symptoms and
includes analgesics and
antipyretics, ensuring adequate fluid intake and avoid-
ing exposure to irritants,
particularly tobacco smoke.
Although prescribed frequently, antitussives and
expectorants are not useful.
There is growing concern
about side effects from antitussives in children under
two years and a recent
Cochrane review failed to
find any benefit in any age
1
group.
Antibiotics do not relieve
symptoms or improve the
natural history of acute
bronchitis in otherwise
healthy patients.
When to refer
Children with acute bronchitis rarely require referral to a
paediatrician unless they
have complicating underlying disease. However, persistence of symptoms for
more than one month or
recurrence of symptoms of
productive cough should
prompt consideration of
alternative diagnoses such as
asthma, suppurative lung
disease or retained foreign
body. These will usually
require referral to a paediatrician for confirmation.
Croup
CROUP, also known as laryngotracheobronchitis, is caused by a viral
infection of the upper airway. This
infection results in a classic triad of
hoarse voice, barking cough and inspiratory stridor. The condition usually
affects children from six months to
six years of age.
Table 3: Assessing clinical severity of a child with croup
• Mild: barking cough, no or intermittent stridor, no chest retractions
• Moderate: persisting stridor at rest, some chest wall recession or tracheal
tug, child easily pacified and interested in surroundings
• Severe: persisting stridor at rest, marked tracheal tug and chest wall
recession, lethargic or restless, pulsus paradoxis
Epidemiology
The annual incidence of croup
depends on the incidence of infection
with viruses that cause this condition,
but peaks occur in autumn and
spring. The peak incidence occurs in
children aged 1-2 years and is about
60 per 1000 child-years. For reasons
that are not clear, croup is rare in
babies under six months of age and
uncommon in children older than six
years.
Pathogenesis
Croup is due to a viral URTI that
causes generalised mucosal inflammation and oedema of the larynx, trachea and bronchi, followed by epithelial necrosis and shedding. The key
area of airway narrowing is the subglottis, with airway obstruction at this
site responsible for stridor.
Laryngeal inflammation also results
in impaired vocal cord movement,
leading to the characteristic cough. In
addition, fibrinous exudate can sometimes result in pseudomembrane formation, which results in further compromise of the airway.
Several viruses have been implicated
in causing croup, but parainfluenza
virus types 1 and 3 are responsible
for about 80% of cases. Influenza
types A and B, RSV, adenovirus and
metapneumovirus are responsible for
most of the other cases.
Signs and symptoms
Croup normally starts with the typical
barking cough, which often comes on
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| Australian Doctor | 8 May 2009
Table 4: Diagnosing croup
Differential diagnosis
Key features
Croup
Triad of barking cough, stridor, hoarse voice; six
months to six years
Epiglottitis
Toxic (high temperature), drooling, muffled voice,
no cough, may be unimmunised for H influenzae
type B
Retropharyngeal abscess
Sore throat, fever, drooling, no cough
Foreign body
Sudden onset, no fever, stridor and/or wheeze,
difficulty feeding/swallowing if foreign body is
oesophageal
*Stridor at rest indicates airway narrowing of at least 70% (ie, 30% or less residual lumen)
suddenly during the night. Usually this
is preceded by a 1-2-day history of
non-specific symptoms of a viral
URTI, such as rhinorrhoea, sore
throat and fever.
Stridor may develop, which can be
associated with difficulty breathing.
In more severe cases the child may
have evidence of respiratory distress,
with tachypnoea, tracheal tug and
chest wall retractions. Auscultation
usually reveals a clear chest, although
air entry may be reduced in more
severe cases.
Symptoms tend to be worse at night
and may fluctuate in severity, typically
becoming more severe if the child
becomes upset. Croup typically lasts
for 2-3 days, but the cough can persist
for up to two weeks, typically becom-
ing looser in nature after the first few
days.
Assessment and diagnosis
Croup is a clinical diagnosis based on
the symptoms and signs described
above. Although there are several clinical scoring systems these are only
useful as research tools and a basic
classification (table 3), provides a simpler guide to assessment and management.
GP therapy
Formerly a popular treatment, steam
inhalation is not useful in the management of croup and carries the risk
of scalds. Antibiotics also have no role
in the treatment of croup. However,
sitting the child upright on their
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parent’s knee and keeping them calm
is very important.
Corticosteroids are used to treat
upper airway obstruction by reducing airway oedema and inflammation.
They should be prescribed for all but
the mildest cases of croup. Recommended doses are oral prednisolone
1mg/kg, or dexamethasone 0.3mg/kg
given either orally or intramuscularly.
The onset of action seems to be within
1-2 hours.
There is no effect on the cough, and
single doses, repeated as necessary,
should be prescribed (rather than a
three-day course as recommended for
asthma). Doses are given at 24-hour
intervals and if more than three doses
are required the child should see a
paediatrician. Parents whose children
develop recurrent croup should be
encouraged to give a dose of corticosteroid as soon as they can predict a
viral URTI will develop into croup.
When to refer
Croup can cause life-threatening
upper airway obstruction, and children with more severe illness need to
be managed in a centre with access
to staff trained in the management of
paediatric airways.
All children under 12 months
should be referred for a paediatric
assessment, in part so that alternative
diagnoses can be excluded. Older children should also be referred if they:
• Have tracheal, sternal or subcostal
indrawing at rest.
• Look toxic.
• Appear dehydrated, cyanosed or
exhausted.
Children with milder symptoms
should also be referred if their family
circumstances make home care inappropriate or there is uncertainty about
the diagnosis (see table 4).
If patients with recurrent croup have
residual symptoms of stridor or exer-
cise limitation between episodes, referral to a paediatric respiratory physician or ENT surgeon is warranted.
Emergency management
Systemic corticosteroids are prescribed
if this has not already been done. Children with more severe croup may
require treatment with nebulised
adrenaline (1mL 1% solution mixed
with 3mL normal saline; or 1:1000
undiluted at a dose of 0.5mL/kg to a
maximum of 4mL), which reduces
laryngeal inflammation, thus improving the child’s airway. In the circumstance of a child requiring adrenaline,
the GP should call an ambulance for
transfer to hospital.
Nebulised adrenaline lasts for up
to two hours, but rebound worsening of the airway narrowing can occur
and this must be borne in mind.
Repeat doses of adrenaline should be
given as needed. A small number of
children with croup will require intubation to maintain their airway.
Nebulised budesonide (one
1mg/2mL nebule) can be used as an
alternative to adrenaline, although
its onset of action is not as rapid.
The main role for nebulised budesonide is for parent-initiated therapy
in those rare circumstances when
children have a history of frequent
severe episodes and access to ambulance support is poor.
Prognosis
Overall most children with croup
have a mild illness that can be managed at home, with fewer than 5%
requiring admission to hospital. Of
those admitted, only 1-2% need intubation, with a mortality rate for intubated children of about 0.5%. Fortunately, complications are rare in
children with croup although secondary bacterial infection can occur, leading to pneumonia or tracheitis.
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Influenza
Signs and symptoms
INFLUENZA is a highly infectious respiratory disease
caused by the influenza
viruses. Three subtypes cause
disease in humans — influenza
A, B and C — but only the
first two cause clinically significant disease. Influenza
infections are often more
severe than infections caused
by other respiratory viruses
and cause constitutional as
well as respiratory symptoms.
Epidemiology
Outbreaks of influenza are
unpredictable and occur in distinct patterns. Pandemics
occur every 30-40 years and
are due to the emergence of a
novel virus. Pandemics typically occur outside the usual
season and spread rapidly
throughout the world. They
typically have high attack rates
in all age groups and result in
high rates of mortality, even in
previously healthy young
adults.
Epidemics occur much more
frequently, usually every 1-3
years, and are associated with
lower excess mortality. They
occur as a result of antigenic
drift of the viruses, a process
that results in the emergence
of new strains of virus caused
by mutations within the virus
antibody binding sites.
Pathogenesis
Influenza is spread from
person to person via respiratory droplets. The virus binds
to respiratory epithelial cells,
which are rich in receptors,
and enters the cell, where it
replicates. New influenza virions are then shed into the respiratory secretions.
During this process, inflammatory cytokines are produced, which are responsible
for the systemic symptoms of
influenza.
The pathogenesis and virulence of the influenza virus
depend on host factors such
as immunocompetence, and
viral factors, including antigenic variation, ability of viral
shedding to take place and
restriction of the cytopathic
effect of the virus to allow continued replication to take
place.
The incubation period for
influenza is usually 1-4 days.
Children can be infectious for
several days before their symptoms appear and can continue
to shed the virus for more than
10 days.
Uncomplicated influenza
results in respiratory symptoms including dry cough, sore
throat, rhinitis and otitis
media, accompanied by systemic symptoms including
fever, myalgia, headache,
malaise, fatigue, nausea and
vomiting. These symptoms are
typically of acute onset but can
be difficult to differentiate
from other respiratory infections such as RSV.
Influenza usually lasts for up
to a week, although the cough
and malaise can persist for 2-3
weeks in some individuals.
Influenza virus may be responsible for most of the respiratory illness discussed in this
article — bronchiolitis, bronchitis, croup and pneumonia.
Complications of influenza
can occur in patients with preexisting respiratory disease,
but infection can also result in
secondary bacterial pneumonia, cause febrile convulsions
and be associated with
encephalopathy, transverse
myelitis, myocarditis and
myositis in previously healthy
children.
Assessment and diagnosis
The influenza virus may be
isolated from cell culture and,
while this remains the gold
standard and is essential for
monitoring circulating strains,
it is too slow to be useful as a
bedside test.
Suitable samples include
nasopharyngeal aspirates or
swabs, throat swabs, sputum
when available, or bron-
choalveolar lavage fluid.
Rapid results are obtained
by directly detecting viral antigens from these samples using
the technique of reverse-transcription PCR, which provides
a sensitive assay able to differentiate influenza A and B from
other viruses.
GP therapy
The main treatments for
influenza are symptomatic, in
particular, maintaining fluids
and encouraging rest. Antibiotics have no role unless secondary bacterial infection is
suspected. In recent years
antiviral therapy with
oseltamivir (Tamiflu) and
zanamivir (Relenza) have
become available.
The difficulty is picking
which children have influenza
as the cause for their symptoms.
A recent Cochrane review
showed that oseltamivir
reduced the median duration
of illness by 26% (36 hours) in
healthy children with laboratory-confirmed influenza.
There were not enough
data on ‘at-risk’ children (eg
chronic respiratory or cardiac
causes) to make a recommendation although there is no
reason why a similar biological
response would not be anticipated. Commencement of
therapy within 48 hours of
symptom onset is required.
There is some evidence that
oseltamivir may be effective
for prophylaxis if a household
contact has confirmed
influenza.
When to refer
Patients who look unwell or
in whom the complications
described above are suspected
should be referred to a paediatrician or emergency department with facilities to care for
children. There should be a
lower threshold for referral
among patients with complex
underlying medical conditions.
Influenza vaccination
This is really in the domain of
preventive therapy. For many
years there has been a standard recommendation for children with complex medical
conditions to receive influenza
vaccination (see The Australian Immunisation Hand3
book 9th edition).
However, otherwise healthy
children can benefit too. A
recent report from SA highlighted that there were more
hospitalisations from influenza
in the <2-year age group than
in those over 65, and even in
those over 85. After three
deaths from influenza in 2007
in WA in previously healthy
children, routine vaccination
for children aged between six
months and five years has
been recommended in that
state.
Children can be immunised
with influenza vaccine from
six months of age. Children
under nine years need two
doses at least one month apart
the first time they receive the
vaccine (single doses are
required in subsequent years).
The principal contraindication
is allergy to eggs.
Pertussis
WHOOPING cough is an acute respiratory tract infection first described
in the 1500s. Most cases are caused
by Bordetella pertussis, with B parapertussis responsible for about 5%
of cases.
Epidemiology
Whooping cough epidemics occur
every 2-5 years. There are 20-40 million cases of whooping cough annually worldwide, 90% of which occur
in low-income countries and result
in an estimated 200,000-300,000
fatalities a year.
Whooping cough is spread by respiratory droplets and is highly contagious. After exposure to an acute
case, 70-100% of unvaccinated
household contacts and 50-80% of
unvaccinated school contacts will
become infected. Infants under 12
months are at highest risk of complications and death.
Young infants do
not always have
the characteristic
whoop and can
present with
apnoea even
before the cough
is recognised.
whooping cough are paroxysms of
cough followed by an inspiratory
whoop and/or vomiting. These
symptoms are usually preceded by a
catarrhal phase lasting a week or two
that resembles the common cold,
with coryza and a non-productive
cough. The paroxysmal phase lasts
for several weeks, usually reaching
its peak of severity in the first two
weeks before gradually improving
over the next 6-12 weeks.
Young infants do not always have
the characteristic whoop and can
present with apnoea even before the
cough is recognised. Infants with
pertussis may look well between
paroxysms, without chest signs.
Petechial and/or subconjunctival
haemorrages may be evidence of the
severity of the coughing paroxysms.
Young infants are at greatest risk of
complications including encephalopathy, pneumonia and feeding problems.
Pathogenesis
Humans are the sole reservoir for
B pertussis and B parapertussis. B
pertussis is a Gram-negative pleomorphic bacillus that spreads via
aerosolised droplets from coughing
of infected individuals. B pertussis
attaches to and damages ciliated respiratory epithelium.
Signs and symptoms
The characteristic symptoms of
Assessment and diagnosis
Pertussis can be diagnosed clinically
in any patient with an acute cough
that has lasted for two weeks or
more and which does not have
another explanation, especially if
there is also a history of paroxysms,
whoop or post-tussive vomiting.
Contact history is also helpful.
The clinical diagnosis can be confirmed by specific diagnostic tests,
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which include direct testing of
nasopharyngeal swabs with nucleic
acid amplification testing (NAAT),
culture, PCR or direct immunofluorescent assays. An additional finding
may be of a significant lymphocytosis
although this is non-specific. Serology (B pertussis-specific IgA) is often
insensitive in the early stages of the
disease and particularly unreliable
from infants.
GP management
Prevention
Vaccination remains the main preventive measure for control of
spread of this disease. The recommended schedule for pertussis vaccination is at two, four, and six
months, and four years of age.
Infants are not protected until they
have had three doses. An adult pertussis booster vaccine (Boostrix) is
given to adolescents who are in
year 10 at secondary school.
Adults who have not been vaccinated with pertussis-containing
vaccine for more than 10 years
have waning immunity and may
contract pertussis and pass it on.
More than half of infants aged
under one year admitted to hospital with pertussis have an adult
family member with clinical or laboratory-proven pertussis.
Although not yet funded (but
licensed for use) adults planning a
pregnancy should have adult pertussis-containing vaccine. Women
already pregnant can be vaccinated
immediately after delivery.
Treatment
Antibiotics do not alter the clinical
course of whooping cough but eliminate B pertussis from the nasopharynx, rendering patients non-infectious. The most effective antibiotic is
clarithromycin 7.5mg/kg (up to a
maximum of 500mg) twice daily for
seven days.
For patients unable to tolerate
macrolides, trimethoprim-sulfamethoxazole is an alternative antibiotic, given for seven days. The dose
is 20mg trimethoprim with 100mg
sulfamethoxazole per dose, twice
daily for children under six months
of age. This dose should be doubled
for older children.
A person who has been coughing
for more than 21 days is no longer
infectious, and antibiotic treatment
is not indicated.
Antibiotics should also be given
to household contacts if the household includes an infant under 24
months of age or a child of any age
who is not fully vaccinated. Antibiotics should also be given to a contact who is a pregnant woman
during the last month of her pregnancy.
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HOW TO TREAT Acute respiratory infections in children
from previous page
Exclusion from school or child care
Children with whooping cough must
be excluded from school or child care
until five days after they start their
course of antibiotics. The Australian
Immunisation Handbook recommends that unimmunised close contacts should be excluded from childcare for 14 days from the date of last
exposure or until five days after start3
ing a course of antibiotics. States and
territories also have guidelines/legislative requirements relating to exclusion
times for unimmunised children from
school or childcare, so GPs are advised
to contact their local public health unit
for information regarding their own
state/territory requirements.
When to refer
Infants under 12 months with pertussis
should be assessed by a paediatrician,
as they are at highest risk of complica-
tions such as apnoea, poor feeding,
pneumonia or encephalopathy.
Older children or adolescents (who
will not have been vaccinated for some
years) may simply present with a troublesome cough and at times the differential diagnosis is unclear. Pertussis
serology (pertussis-specific IgA) can
be helpful in these circumstances.
cardio-respiratory monitoring, fluid
support and continuous oxygen
therapy if there is hypoxia with
coughing.
Investigations such as nasopharyngeal PCR or culture are performed but antibiotics are usually
prescribed if the clinical suspicion
of pertussis is high.
Specialist management
Prognosis
Specialist management involves
Infants born prematurely and
patients with underlying cardiac,
pulmonary, neuromuscular or neurological disease are at high risk for
complications of pertussis (pneumonia, seizures, encephalopathy,
death).
The cough may persist for three
months (‘the 100-day cough’) and
recrudesce with any subsequent respiratory infection, although rarely
enough to warrant readmission to
hospital.
Pneumonia
PNEUMONIA can be
defined as inflammation and
consolidation of the lung
parenchyma, caused by an
infectious organism. Most
cases of pneumonia in children are community acquired
and occur in previously
healthy children. The diagnosis is clinical and does not
require chest X-ray confirmation.
Figure 2A. A chest X-ray of a four-year-old child who presented
with high fever, lethargy and cough. On examination there was
reduced air entry in the right lower zone with bronchial breath
sounds. The chest X-ray shows opacification in the right lower
lobe with some air bronchograms. Note: the right heart border
appears clear suggesting the infection is not in the middle lobe.
Figure 2B. The same four-year-old child after 36 hours of intravenous penicillin. He is more
tachypnoiec with high fever. The air entry on the right is further reduced and the percussion note is
stony dull. This suggests the pneumonia has become complicated by a pleural effusion or
empyema. The chest X-ray now shows more extensive opacification with mediastinal shift to the
left and evidence of the effusion/empyema.
Heart shifted
to the left,
suggesting
large volume
of pleural
fluid.
Epidemiology
Pneumonia is most common
in younger children, with an
annual incidence of 35-40
cases per 1000 children under
five years of age, which falls
to seven cases per 1000 in
adolescents aged 12-15 years.
The age of the child is
important in determining the
likely pathogen responsible.
In neonates, group B streptococcus and Gram-negative
enteric bacteria are the most
common pathogens.
Beyond the neonatal
period, viruses are by far the
most commonly implicated
pathogens in children during
the preschool years, with
RSV, parainfluenza, adenovirus,
rhinovirus, influenza and
cytomegalovirus all potential
causes in this age group.
In children over five years
of age, S pneumoniae is the
most common cause, with M
pneumoniae and Chlamydia
pneumoniae the next most
frequent causative organisms.
Pathogenesis
S pneumoniae is carried in
the nasopharynx in about
50% of healthy children
without causing symptoms.
Various factors can lead to
invasive disease, such as the
acquisition of a new serotype
or concomitant viral infection
such as influenza, which
increases the attachment of
the streptococcus to the respiratory epithelium.
The organisms reach the
lower respiratory tract by
haematogenous seeding,
although inhalation of infectious particles may be implicated. In the alveoli, the
organisms multiply and
spread from alveolus to alveolus via the pores of Kohn.
Signs and symptoms
Pneumonia frequently starts
with a high fever accompanied by tachypnoea. Cough
is often absent initially, particularly when the infection is
due to S pneumoniae. This is
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| Australian Doctor | 8 May 2009
More extensive
opacification
which may be
the pleural
space fluid or
more extensive
pneumonia.
because the inflammatory
process occurs predominantly
within the alveoli (where
there are few cough receptors) in the early stages of this
infection. Cough then
becomes more prominent as
inflammation spreads and
debris accumulates in the airways.
Respiratory rate can be
hard to count in healthy restless children, but tachypnoea
is an important sign in pneumonia, as it is associated both
with severity and with
increased likelihood of underlying consolidation. Chest
recession may be an accompanying clinical feature.
Auscultation typically
reveals crackles and/or
bronchial
breathing.
Localised signs increase the
chance of the infection being
bacterial, while generalised
signs may be more typical of
viral or mycoplasma infection. However, these are not
particularly specific or sensitive findings.
The presence of wheeze suggests either a viral or, particularly in school-age children, a
mycoplasma infection. The
classic mycoplasma prodrome
is high fever and headaches
before the cough appears, but
almost any presentation could
also be mycoplasma. It is generally stated that mycoplasma
is more common in the
school-age group (compared
with preschoolers/infants),
although this assertion is being
questioned.
Children with pneumonia
may present with abdominal
pain, particularly if the infection involves the lower lobes.
The pain can be quite severe
and is due to referred pain
from the diaphragmatic
pleura. Older children may
also complain of chest pain.
Assessment and diagnosis
Pneumonia can be diagnosed
clinically in most cases,
although it is extremely difficult to distinguish bacterial
from viral causes on clinical
grounds. Routine chest X-ray
in children with uncomplicated lower respiratory tract
infections is not necessary. A
chest X-ray is helpful if the
diagnosis is in doubt, or the
child does not respond to
therapy as expected, or complications (such as parapneumonic effusion or empyema)
are suspected. Other investigations, including FBC and
acute-phase reactants, are also
unnecessary in most cases and
do not help distinguish
between viral and bacterial
pathogens.
Urine testing for the presence of antigens is another
unhelpful test, as their presence is not specific for pneumonia. However, culture of a
clean-catch sample of urine
should be performed in a
febrile child if the infective
cause is unknown, to exclude
the possibility of an underlying UTI.
Serology
(IgM)
for
mycoplasma has little role in
the GP setting because of the
delay in receiving results.
Blood cultures should be
performed in children with
more severe disease who
require admission to hospital,
although these prove positive
in fewer than 10% of cases.
Nasopharyngeal aspirates
are useful for diagnosing viral
infections, particularly in
younger children who require
admission to hospital.
The presence of bacteria in
these samples cannot be used
to make a diagnosis, as they
are commonly found as commensals. In children with
pneumonia complicated by
parapneumonic effusion,
pleural fluid should be
obtained if possible.
This should be sent for bacterial antigen detection as well
as microscopy and culture.
GP therapy
It is difficult to differentiate
viral, mycoplasma and bacterial causes of pneumonia by
clinical examination. Added
to this is concern regarding
the increasing incidence of
antibiotic resistance. Thus,
young children presenting
with mild symptoms of lower
respiratory tract infection do
not require antibiotics.
In more severe cases, if
antibiotics are prescribed,
amoxycillin (10-25mg/kg
eight-hourly) should be the
first choice, as it is effective
against the most common
pathogens, is well tolerated
and cheap.
Alternatives to amoxycillin
include roxithromycin (2.54mg/kg
12-hourly).
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Macrolide antibiotics may be
used as first-line treatment in
children over five years, as
mycoplasma
infections
become more common in this
age group.
An essential part of the
management of pneumonia in
children in the community is
the provision of information
to the child’s family to allow
them to manage fever, prevent dehydration and identify
signs of deterioration in the
child’s condition.
When to refer
If pulse oximetry is available,
a key indication that the child
is likely to require admission
to hospital is hypoxaemia,
that is, an oxygen saturation
of <92%.
Other indications include
tachypnoea (respiratory rate
>70 breaths/minute in infants
less than 12 months or >50
breaths/minute in older children) as well as poor feeding
or evidence of dehydration,
apnoea or grunting, or if the
family is unable to provide
appropriate care.
Patients should be reviewed
regularly within the first 48
hours of illness, as failure to
improve, or deterioration,
within this time frame is an
indication for review by a
paediatrician.
Specialist management
Oxygen is provided if the
child is hypoxic. Antibiotics
are given if this has not been
done previously, and may be
administered intravenously in
severe cases of pneumonia or
if the child is unable to
absorb oral antibiotics (eg,
due to vomiting).
The first-line IV antibiotic
for an uncomplicated pneumonia should be benzylpenicillin 30mg/kg six-hourly
(60mg/kg four-hourly if infection is severe, but referral in
these circumstances is
advised). Chest physiotherapy
is not beneficial and has no
place in the management of
pneumonia in children.
The development of respiratory failure may necessitate
transfer to the intensive care
unit for ventilatory support.
Parapneumonic effusions
may
require
surgical
drainage.
Prognosis
Death from pneumonia is
rare in the developing world
and the vast majority of children recover completely.
Most children with a S pneumoniae infection respond
within 24 hours; failure to do
so suggests more serious
infection or development of
complications such as parapneumonic effusion/empyema.
Other complications can
occur, such as lung abscess
and metastatic infections,
including osteomyelitis and
septic arthritis.
Children with no pre-existing conditions who follow a
standard course with rapid
resolution of symptoms do
not need a progress chest Xray if one was taken initially.
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HOW TO TREAT Acute respiratory infections in children
GP’s contribution
DR GED FOLEY
Mosman, NSW
Case study
JS, 18 months, presented with
a history of an URTI four
weeks before, followed by an
intermittent cough. Over the
preceding two days the cough
had become worse and was
associated with fever, malaise,
rapid breathing and poor
appetite. There was no relevant past or family history.
On examination, JS was
febrile with a temperature of
38.5°C and his respiratory rate
was 48 breaths/minute. ENT
examination was normal. Respiratory examination revealed
scattered expiratory wheeze
and scattered crackles. JS was
prescribed amoxycillin and
supportive measures and a
review in four days was
arranged.
He returned in three days,
at which time he was still
febrile and coughing. On
examination his temperature
was 38.0°C, pulse 120
beats/minute and respiratory
rate 40 breaths/minute. He
was once more found to have
scattered expiratory wheeze,
although now he had some
focal signs at the right midzone and base, with localised
inspiratory crackles and
slightly reduced air entry.
The possibility of an atypical infection was considered
and erythromycin was added.
He was also given inhaled
salbutamol via a spacing
device and second-daily review
was organised.
Initially JS improved on this
regimen and was more settled
after two days. However, at
further review (seven days
after initial presentation), he
had deteriorated again. He
was febrile with a temperature
of 37.9°C, tachypnoeic and O2
saturation was 94% on room
air. He had intercostal recessions and the focal signs at the
right base were more marked.
He was referred to the emergency department.
JS was an inpatient for only
two days and was treated with
oxygen and roxithromycin.
Subsequent sero-logy indicated
infection with Chlamydia
pneumoniae. His cough persisted for many weeks, and six
months later he still has some
mild shadowing in the right
middle lobe on chest X-ray
(being monitored by the paediatric team).
Questions for the author
Is there a case for initiating
amoxycillin treatment together
with a macrolide antibiotic
when a child presents with
How to Treat Quiz
focal chest signs and a clinically severe infection?
No. The appropriate strategy was employed — starting
with a simple antibiotic
(amoxycillin) in this age group.
The development of focal signs
would warrant a chest X-ray if
the child was not improving.
Atypical organisms and viral
infections may cause localised
disease but I would be covering
for bacterial infection if signs
were localised.
Previous studies have suggested
that young children with purulent rhinorrhoea, fever and a
chesty cough have focal areas
of pulmonary infection that are
not apparent on examination.
Should we be initiating antibiotic treatment in such children?
No. This constellation of
features is most likely viral in
origin. If the child looks systemically well and there are no
pulmonary signs, there is no
need to start antibiotics.
Persistent symptoms, and
particularly tachypnoea and
chest signs, are likely to
warrant antibiotic treatment.
We are currently seeing many
cases of pertussis in the schoolage population. Should we be
offering antibiotic treatment to
classmates who have been in
close contact with a patient
with pertussis?
Data on contact prophylaxis
are scarce, and defining close
contact can be problematic.
The principles as outlined in
the ninth immunisation handbook are to protect young children (<24 months) who have
not been immunised completely (this would include all
infants under six months, none
of whom have had three doses
of DTPa).
If any contacts come from
such a household or include a
woman in her last month of
pregnancy (if she delivers, the
baby could be at risk of pertussis) the contact should
receive antibiotic prophylaxis. I
would also offer prophylaxis
(and immunisation) to contacts
who have not been immunised.
References
1. Smith SM, Schroeder K,
Fahey T. Over-the-counter
medications for acute cough
in children and adults in
ambulatory settings.
Cochrane Database of
Systematic Reviews 2008,
Issue 1. Art. No.:
CD001831. DOI:
10.1002/14651858.CD0018
31.pub3.
2. Matheson NJ, Harnden A,
Perera R, Sheikh A,
Symmonds-Abrahams M.
Neuraminidase inhibitors for
preventing and treating
influenza in children.
Cochrane Database of
Systematic Reviews 2007,
Issue 1. Art. No.:
CD002744. DOI:
10.1002/14651858.CD0027
44.pub2.
3. National Health and
Medical Research Council.
The Australian
Immunisation Handbook 9th
Edition 2008:
www.health.gov.au/internet/
immunise/publishing.nsf/
Content/Handbook-home
INSTRUCTIONS
Complete this quiz online and fill in the GP evaluation form to earn 2 CPD or PDP points. We no longer accept quizzes
by post or fax.
The mark required to obtain points is 80%. Please note that some questions have more than one correct answer.
Acute respiratory infections in children
— 8 May 2009
1. Jared, six months, presents with a twoday history of a fever and cough, preceded
by a runny nose for a few days. On
examination he is tachypnoeic with chest
wall recessions and widespread crackles
and wheeze. Your provisional diagnosis is
bronchiolitis. Which TWO features would be
suggestive of severe infection?
a) Fluid intake <50% of normal in the
preceding 24 hours
b) Respiratory rate of 40 breaths per minute
c) Lethargy
d) Oxygen saturation of 95%
2. Which TWO statements about
bronchiolitis are correct?
a) Bronchiolitis is best diagnosed by chest X-ray
b) Treatment of bronchiolitis in hospitalised
infants is largely supportive with
supplemental oxygen and fluid replacement
c) Bronchodilators are a useful additional
therapy in infants under 12 months of age
d) About 10% of children develop a postbronchiolitic syndrome with cough and
wheeze that can recur intermittently for
several years
3. Which TWO statements about bronchitis
in children are correct?
a) Most cases of acute bronchitis are due to
viruses
b) Antitussives and expectorants are useful for
symptomatic relief of bronchitis in children
c) Antibiotics will relieve symptoms of
bronchitis and result in shorter recovery
times in most patients
d) Recurrent episodes of bronchitis are
uncommon
4. Which TWO statements about croup are
correct?
a) Stridor at rest indicates airway narrowing of at
least 30%
b) Key features of severe croup include drooling
and a toxic appearance
c) All children under 12 months with symptoms
of croup should be referred for a paediatric
assessment
d) Features of severe croup may include
lethargy or restlessness
5. Tania, two years, presents with a hoarse
voice, barking cough and stridor, which
came on overnight. Which TWO statements
about the management of croup are
correct?
a) Steam inhalation is useful in the
management of mild croup
b) Oral corticosteroids should be prescribed
for all but the mildest cases of croup
c) Children with more severe croup may
require nebulised adrenaline
d) There is no role for nebulised budesonide in
the management of croup
6. Which THREE statements about influenza
in children are correct?
a) Children with influenza are not infectious
before their symptoms appear
b) Influenza virus may be responsible for
ONLINE ONLY
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bronchiolitis, bronchitis, croup and
pneumonia
c) Detection of the influenza virus by culture is
essential for monitoring strains but too slow to
be a useful bedside test
d) Children under nine years need two doses at
least one month apart the first time they
receive influenza vaccine
7. Which TWO statements about clinical
features and diagnosis of pertussis infection
are correct?
a) Whooping cough is not highly infectious, with
only about 30% of unvaccinated household
contacts becoming infected after exposure
b) The characteristic paroxysmal phase of
whooping cough is usually preceded by a 12-week catarrhal phase
c) Young infants with pertussis infection can
present with apnoea even before the cough is
recognised
d) Bordetella pertussis-specific IgA serology is
the gold standard test for diagnosis in the
early stages of the disease, especially in
infants
8. Which TWO statements about managing
and preventing pertussis infection are
correct?
a) Antibiotics will reduce the severity and risk of
complications of whooping cough
b) A person with whooping cough who has been
coughing for more than 21 days is no longer
infectious
c) Antibiotics should be given to household
contacts of those with whooping cough if the
household includes an infant under 24
months of age
d) Adults who received the full course of
recommended vaccinations in childhood have
lifelong immunity to pertussis
9. Which TWO statements about causes and
presentation of pneumonia in children are
correct?
a) Streptococcus pneumoniae is the most
common cause of pneumonia in preschoolaged children
b) Cough is frequently the first symptom in
children with pneumonia, particularly when
the infection is due to S pneumoniae
c) Tachypnoea is associated with increased
severity of pneumonia and increased
likelihood of underlying consolidation
d) Children with pneumonia may present with
abdominal pain
10. Which TWO statements about diagnosing
and managing pneumonia in children are
correct?
a) All children with a clinical diagnosis of
pneumonia require X-ray confirmation of the
diagnosis
b) An FBC will help to distinguish between viral
and bacterial causes of pneumonia
c) If oral antibiotics are prescribed, amoxycillin is
generally the first choice in children under five
years
d) Macrolide antibiotics may be used as first-line
treatment in children over five years
CPD QUIZ UPDATE
The RACGP now requires that a brief GP evaluation form be completed with every quiz to obtain category 2 CPD or PDP points for the 2008-10 triennium. You
can complete this online along with the quiz at www.australiandoctor.com.au. Because this is a requirement, we are no longer able to accept the quiz by post
or fax. However, we have included the quiz questions here for those who like to prepare the answers before completing the quiz online.
HOW TO TREAT Editor: Dr Wendy Morgan
Co-ordinator: Julian McAllan
Quiz: Dr Wendy Morgan
NEXT WEEK Excessive daytime sleepiness is a common symptom in general practice.The next How to Treat focuses on the primary brain disorders that can cause excessive daytime sleepiness (especially
narcolepsy and idiopathic hypersomnia). The authors are Dr Anup Desai, senior staff specialist, department of respiratory and sleep medicine, Prince of Wales Hospital, Randwick; consultant physician in
private practice, Camperdown (Brain and Mind Research Institute) and Randwick; and clinical senior lecturer, faculty of medicine, University of Sydney; and Dr Ben Kwan, respiratory advanced trainee registrar, Prince of Wales Hospital, Randwick, NSW.
34
| Australian Doctor | 8 May 2009
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