There are three ways of testing allergies in children.
one is a blood test, second is a skin prick test.
and third is an oral food challenge. In the blood test, we take the blood from
the child and we test for any number of antigens that we suspect that can be causing problems.
In the skin prick test, we take the antigen and we do the skin prick. We prick the skin
with all these antigens and we read the results in 15 minutes. Both the tests have equal sensitivity
and specificity. That means the reliability of both the tests is exactly the same. These
tests are not 100%. If the test is positive, that does not mean the child is allergic
to it. They may be sensitized to it. On the other hand, if the test is negative, that
again does not mean that the child can have the substance because they can still be allergic
to it. To confirm the diagnosis, we do what we call
an oral food challenge, in which the child is given a substance to eat in a controlled
setting in a hospital, with all the resuscitation equipment to hand. If the child is
able to tolerate it, then obviously, the child is not allergic to it. On the other hand,
if the child develops a reaction, then the child is allergic to the substance. That is
the best test that we can do for allergy.
We don’t know to be honest, but there are
certain families which have the tendency to develop allergies. They have allergic conditions
like cow’s milk protein allergy, various nuts allergies, eczema, asthma, allergic rhinitis.
They are called atopic families. There is something in their genetics which make these
children or even adults prone to be allergic to certain conditions.
Most people are okay with nuts, but if you give nuts to these children, they’ll react
to it. Their body recognises that a nut is a foreign antigen and they mount an allergic
reaction to it. We don’t know what causes allergy but we do know that it runs in families.
Why have allergies have become so common is controversial and we’re not 100% sure why it’s happened.
But there are certain factors to blame like the hygiene hypothesis. What that means is that we
have become very hygienic. We try to clean everything and keep everything 100% bacteria-free.
That is apparently not a good thing because our body has forgotten how to fight against
various antigens and bacteria. The body is now recognising these antigens like normal
things which are absolutely fine. The body thinks that these are foreign bodies and they
try to mount a reaction to it. That we think might have led to the increase in the allergies
in this day and age. Also, we used to eat everything without any
problem. Nowadays, there was actually a guidance which advises mothers, expectant mothers to
not to eat nuts and various allergenic food. That was not a good advice because that has
led to an increase in allergies. Now, the recent advice is to eat everything as much
as you can if you’re already not known to be allergic to that particular substance.
Allergy symptoms are different in different age groups. For example, in a baby who’s
only given milk, the development of dry skin or eczema, if the baby starts to vomit after every
feed, is very irritable, constipated or has runny stools or sometimes passes blood in the stool,
these can be symptoms of milk allergy. For food, it’s very obvious. If you eat
that particular food, for example a peanut, and you start developing redness around the
face, itchy throat, you may start to vomit or sometimes difficulty in breathing. That’s
again a very clear symptom of allergy. There can be some situations in which the allergies
are a bit more difficult to diagnose where you may have gastrointestinal symptoms like
chronic diarrhoea or you may have a very dry skin in which case you may be allergic to
something which will have to be tested to confirm. You may have hay fever and maybe
allergic to pollen. That again has to be tested and that’s the way to confirm that you are
allergic to pollen which might be causing your hay fever.
It depends on what food allergy you have. If you have allergy to milk, that can be two
types. One is called IGE mediated and the other is non-IGE mediated. Non-IGE mediated,
you grow out of by the time you’re one to two years of age. If its IGE mediated milk
allergy, then it can take a while. It can take up to 10 years before you grow out of it.
Egg allergy, you grow out of it between seven to eight years of age. Nut allergy is a difficult
one. The chances of growing out of nut allergy are not that common. If you have a peanut
allergy, which is actually a legume, then the chances of growing out of that is 1 is to 10 that is 10%. While if
you have a tree nut allergies like hazelnut, cashew nut, or Brazil nut, then the chances
of growing out of it is only 1 in 20, so that's even less than peanut. Nut allergies are really difficult to grow out of.
There is something called immunotherapy which is recently being tested. It’s not available
via the NHS at the moment. But immunotherapy is something where we give the substance you’re
allergic to in small quantities and we expect you to develop a tolerance. That's again
in experimental phases at the moment.
The treatment is mainly symptomatic. If you
have eczema, then we use emollient and steroids and obviously, the main treatment is avoidance
of the allergen. If you are allergic to milk, then we have to try a different type of milk
which does not have the cow’s milk protein. If you’re allergic to nut, then you avoid
those nuts. If you’re allergic to house dust mite, then you keep the house as dust
mite free as possible. The treatment in terms of medication is depending
on the symptoms. If you have asthma, then it’s treated with the inhalers like, you must have heard of the relievers
and preventers, which are usually steroids. The relievers are some bronchodilators which
help to dilate the lungs. The mainstay of treatment is antihistaminics because histamine
causes a lot of problems related to allergy to we take antihistaminics like Piriton which
is chlorphenamine or cetirizine or fexofenadine. If you have real difficulty in breathing,
which is called anaphylaxis in which you can collapse, the treatment is via adrenaline,
which has to be given intramuscularly. Children with nut allergy who have had breathing problems
usually carry what we call an adrenaline auto-injector like epi pen which is lifesaving.