Allergic Diseases in Children: The Science, the Superstition and the

Transcription

Allergic Diseases in Children: The Science, the Superstition and the
Final Reading
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General
Introduction
Allergic diseases have become the most common group
of diseases in children, affecting more than 20% of
children worldwide. During the last three decades there
has been a tremendous increase in allergy disorders in
children, mainly in the developed countries (Fig. 1).
Allergic diseases are a growing health problem across
the world.
The increase in allergic diseases can be attributed to
adoption of a Western lifestyle: It is the price we have to
pay when we reach a higher standard of living (Fig. 2).
In general, it can be stated that the wealthier a country
is, the more commonly allergy will occur among its
children.
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
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Prevalence
Diagnosed asthma
Fig. 1 The increase in incidence of asthma in Singapore from
1967 to 2001. (from: Wang and co-worbers, Arch Dis Child
(2004) 89:423.)
Fig. 2 A modern child’s bedroom contains more than
a bed. Most children have their own television set and
computer, spending more time in the bedroom.
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
© World Scientific Publishing Co. Pte. Ltd.
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Table 1 Inheritance of Allergy
Parents
Risk for children
1.
both are non-allergic
15 – 20%
2.
only father is allergic
40%
3.
only mother is allergic
50%
4.
both are allergic
70%
5.
both are very allergic
For most people with an
allergic disease, allergy would
first appear during infancy or
childhood. It is not surprising,
then, that allergic disorders rank
first among children’s chronic
diseases.
Any child can become allergic,
but children from families with a
history of allergy are more likely
to become allergic. Children may
inherit the tendency to become
allergic from their parents, but
not all of them will develop
active allergic disease (Table 1).
On the other hand, children
with no allergy in the family can
develop symptoms of allergy.
The mechanisms of inheritance
are still poorly understood. One
thing is for sure: inheritance of an
allergy is a complex phenomenon
as many modes and many types
of genes are involved.
> 90%
The more allergies in the
parents, the higher the risk for
the child to become allergic.
However, even if both parents
are non-allergic, there is still a
15 – 20% risk that the child will
become allergic.
Allergies can show up in
different ways in children. Some
children develop skin rashes
(eczema or hives) from allergy;
others suffer from asthma and
still others develop allergy of the
nose (allergic rhinitis), such as hay
fever (also referred to as seasonal
allergic rhinitis).
Allergic rhinitis is the most
common of all allergy problems,
followed by asthma and eczema
(Fig. 3).
Allergic rhinitis (Fig. 4) is
characterized by a runny, itchy
nose, sneezing, postnasal drip
(dripping of phlegm in the
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Fig. 3 Asthmatic girl treated with a nebulizer during
an acute asthma attack.
Fig. 4 A child with allergic rhinitis.
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
© World Scientific Publishing Co. Pte. Ltd.
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throat which results in cough)
and nasal congestion. The child
with this allergy may also have
itchy, watery and red eyes and
chronic ear problems. Allergic
rhinitis can occur at any time of
the year, seasonally or year-round.
In most Asian countries with a
tropical climate, seasonal rhinitis
is extremely rare because of the
lack of seasons (no pollen season
in tropical countries).
Asthma is an allergic disease of
the lower airways (of the bronchi).
Asthma presents as attacks of
shortness of breath, cough and
wheezing (i.e. a whistling sound
during breathing). Asthma can
also present as a chronic cough.
Allergy is not the only cause of
asthma. In particular in young
children, asthma can also be
triggered by viral infection of the
airways.
Eczema or atopic dermatitis
is characterized by the existence
of a chronic itchy rash. Usually
children with eczema (Fig. 5)
have very dry skin and show red
patches on the face, neck, elbow
folds, back of the knees, ankles
and wrists.
Other allergic manifestations
are: urticaria (hives) (Fig. 6),
vomiting and chronic diarrhea,
and failure to thrive. In some
children, allergy can present as
a severe and dangerous event,
called anaphylactic shock. These
children need urgent and intensive
treatment, as manifestations of
anaphylactic shock can become
fatal.
The Allergens usually causing
allergic symptoms are inhaled
allergens that can cause the
symptoms through the airways.
In other cases, various different
foods, such as peanuts or seafood,
can be responsible for allergic
symptoms.
Just remember
• Allergies are common in
children and can manifest in
different ways
• T h e m o s t c o m m o n
manifestation of allergy is
allergic rhinitis
• Allergy to inhalants is far
more common than allergy to
foods
• In tropical regions, house dust
mites (Fig. 7) are the main
cause of allergy
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
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Fig. 5 A child with eczema. Baby with severe
eczema in the face.
Fig. 6 Child with acute urticaria (courtesy of Prof. Peter
Smith, Australia).
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
© World Scientific Publishing Co. Pte. Ltd.
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Fig. 7 House dust mite. The various different types
of house dust mites are the most common cause of
childhood allergies in tropical countries.
About the
book
The purpose of this book is to
share information and knowledge
on allergic disorders in children
with everybody, especially with
parents of allergic children.
Allergic disorders in children are
a common and growing problem.
From my experience, many
parents lack correct information
on allergy. This has led to wrong
approaches in dealing with
the problem, as well as false
expectations and disappointment.
Moreover, parents will keep
looking for a cure for their child,
and may end up with all kinds of
non-scientifically proven testing
and treatments. Sometimes these
treatments can be harmful for
the child.
The book comprises twelve
chapters, each covering a specific
aspect of allergy in children. The
first part covers general issues,
such as underlying mechanisms,
allergens, and epidemiology of
allergic diseases. In the second
part, specific allergic diseases
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
© World Scientific Publishing Co. Pte. Ltd.
http://www.worldscibooks.com/medsci/7304.html
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are covered. The book ends with
considerations on diagnosis and
treatment, and offers suggestions
for future research on allergy in
children. At the end, common
questions on allergy are answered
briefly.
I hope that this book will
provide useful information to
the public, especially parents of
allergic children. Based on current
scientific information, the book
should help allergic children to
obtain optimal diagnosis and
treatment of their allergic disease.
In case you have any questions or
remarks or views, please email me
on: allergyinchild@wspc.com
I will try to answer ASAP.
Hugo Van Bever
ALLERGIC DISEASES IN CHILDREN - The Science, the Superstition and the Stories
© World Scientific Publishing Co. Pte. Ltd.
http://www.worldscibooks.com/medsci/7304.html
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