With one in five Irish children affected by the disease, should we be getting worried, asks FIONA REDDAN.
IRELAND
HAS the fourth highest prevalence of asthma in children in the world and one in
five Irish children will now develop the illness. But what’s behind the rise? “The
short answer is that no one knows for sure, but there are plenty of theories,”
says Dr Peter Greally, consultant respiratory paediatrician based in the
National Children’s Hospital, Tallaght and Our Lady’s Hospital for Sick
Children, Crumlin.
Dr
Basil Elnazir, medical chairman of the Asthma Society of Ireland and paediatric
respiratory consultant at Tallaght hospital and clinical senior lecturer at
Trinity College Dublin, agrees. “The right answer to this is we don’t know;
it’s a very complicated issue,” he says.
One
of the most common theories put forward is the “hygiene hypothesis”, whereby in
the developed world, children’s immune systems don’t have enough to do fending
off parasitic infections, so part of it turns on itself. In underdeveloped
parts of the world, asthma and allergies are far less common. Indeed, Greally
points to data linking a country’s GDP with the prevalence of asthma. “In
general terms, poorer underdeveloped countries have lower rates of asthma,” he
notes, adding, “It’s certainly an attractive theory, and it does explain a part
of it, but there are always exceptions to any theory. “Genetics play a
significant role, but there hasn’t been a significant change in the genetic
pool to account for this sharp increase [in asthma],” Elnazir notes, adding
that it could be down to the interaction between genetics and the environment. “Genetics
load the gun, but the environment pulls the trigger,” he says.
What
is clear is that asthma runs in families. Maternal history of asthma is
typically a strong predictor in a child, while if both parents have an atopic
condition (asthma, eczema, nasal conditions or allergies), then the risk of the
child developing asthma is about 80 per cent. On the other hand, if neither
parent has such a condition, then the child’s risk of developing asthma is just
14 per cent. However, while asthma might be at elevated levels, if one in five
children displays symptoms of asthma, the majority will nonetheless have a mild
version. “Only a minority of patients have it very, very severe. We grade
asthma according to how much medication is required to control the condition,”
Greally says. In order to treat asthma effectively, it can be important to
identify the trigger, which can include viral infections, exposure to dust
mites or pollen, and a change in the weather. Like most diseases, asthma comes
in many shapes and forms. Younger children, particularly pre-school, get
asthma-type symptoms in conjunction with a viral infection.
The
most common form of asthma however is allergy-based asthma, whereby children
have an allergy to house dust mites. “A dust mite allergy is the most common
one we find, and avoidance of dust mites is a very common recommendation,” says
Greally. This means using a special type of fabric for pillows, keeping the
child’s bedroom at a low humidity, and as dust free as possible. A change in
temperature is another trigger. In a trend that is reproducible every year,
about two weeks into the new school year there will be an upsurge in the number
of asthma incidents. According to Greally, this is due to the re-emergence of
the cold virus in the community. “People with asthma are very sensitive to the
cold virus, and this can be an important trigger,” he says. But the good news
for many parents is that most children will grow out of it. “The best guidance
we have, based on international studies, is that 60-70 per cent will outgrow
it,” says Elnazir. “Those with a good prognosis are male, have generally milder
asthma that doesn’t require hospitalisation, and need less treatment to control
it,” Greally adds, noting that while more boys are diagnosed with asthma than
girls in childhood, more boys also tend to grow out if it, meaning that the
gender balance reverses in adulthood.
Given
that asthma can’t be prevented, controlling it is important, and in this
regard, it is important that parents understand the myths that surround asthma.
For example, many parents of children with asthma may have been advised to stay
away from dairy products such as milk but, according to Greally, there is no
medical reason to do so, describing it as an “urban myth”. “Many parents come
to me asking if excluding milk could improve asthma. But there’s no basis for
that in terms of the science behind asthma and it’s highly unusual for a
clinician to recommend an exclusion diet to treat asthma,” he says.
Another
myth is that there is a simple test for asthma. “We don’t have one test for
asthma. What we have is a constellation of symptoms and clinical examination
and investigations,” says Elnazir, adding that another misconception, which
frequently comes up, is that taking an inhaler makes you dependent on it. “Inhalers
do not cause any dependency,” he advises. And early in the new school year, it
might be time to reflect on your child’s illness. “The message for parents is
that if your child is having regular symptoms, such as coughing on exertion or
night coughing, has a diagnosis of asthma and is using a lot of relieving
inhaler, then you really need to get the condition under control,” Greally
says. As Elnazir says, you want to be able to say, “I have asthma but asthma
doesn’t have me.”
Irish Times
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