When allergies turn life-threatening
By BRIGITTE ROZARIO
The immune system is a body's surveillance and defence system. It helps the body fight allergens, bacteria and viruses.
When a child's immune system is compromised it can result in allergies or allergy-like symptoms, immune deficiency, and autoimmune disorders and diseases.
Clinical immunologist / allergist and paediatrician Dr Amir Hamzah Abdul Latiff explains that allergies are just one disorder that can occur.
“It's a hypersensitivity reaction via the immune system, hence it's called an allergy. There are probably more hypersensitivity reactions not via the immune system and these are not allergies but rather an intolerance or adverse drug reaction,” explains Dr Amir, who is also president of the Malaysian Society of Allergy & Immunology (MSAI) and council member of the World Allergy Organisation (WAO).
Most of the children who come to see Dr Amir Hamzah are allergy cases.
“Worldwide, about 30-40% have an allergy and here in Malaysia it is heading towards that percentage as we become a developed nation. When we talk about allergy we talk about eczema, food allergy, allergic rhinitis and allergic asthma. In children, asthma tends to be due to some form of allergy and of course it's mainly going to be environmental allergens, be it indoors or outdoors. Here in Malaysia, it's mainly indoor allergens and that would be the house dust mites.
“We don't have good figures here for the number of food allergy cases but worldwide 6-8% of children can have food allergy and the commonest is still cow's milk, egg whites, soya and wheat. As the kids go towards teenage years, it's allergy to peanuts and the tree nuts like hazelnut and almonds.
“It can happen at any time as long as you are exposed to those foods. You may become sensitive but you may not have the symptoms until you get the full-blown scenario,” he says.
According to Dr Amir, the symptoms typically are rashes, itchiness, hives, vomiting, diarrhoea and abdominal pain.
There is a whole spectrum of reactions involved with regards to allergies. It could be just mild hives or it could affect a child's breathing.
It could be a reaction to eating or touching the item or in some cases, even just being in the same room as the item you are allergic to.
Common allergies and their symptoms
According to Dr Amir, eczema tends to manifest more or less around the same time as food allergy in children which is in early childhood, within the first three years.
After that, it might go away and later on the child might develop asthma and allergic rhinitis.
The symptoms for these common allergies are:
Eczema – Dry flaky skin and itchiness.
Asthma – Wheezing episodes.
Allergic rhinitis – Runny nose, blocked nose, sneezing, nose and eye itchiness.
Explaining how an allergy is different from having a cold or the flu, Dr Amir says an allergy is persistent and always occurs after exposure to an allergen.
“Usually, there's no fever and they're pretty well, but they can be a bit tired because of all the symptoms.”
These are the allergies that Dr Amir sees the most. Most allergies are a nuisance and affects the child's quality of life but they are generally pretty mild.
However, parents must always be alert and monitor symptoms as there is also the more severe life-threatening allergic reaction which is anaphylaxis, which is a severe whole-body allergic reaction.
“That usually occurs when two or more systems of the body is affected. For example, a child might have hives, bad blotchy rashes, and at the same time he is also wheezing very badly and finding it difficult to breathe. Or he might have Laryngeal Oedema, where his throat becomes obstructed.
“So, there are two systems affected – skin and respiratory. When it involves two or more systems then it is life-threatening. It can be severe. Or if you have rashes and you're feeling faint – that's because your blood pressure is starting to drop. So you can have low blood pressure and go into anaphylactic shock and the person can faint.
“The extreme result of anaphylaxis is actually death. That's why it should be taken seriously. No doubt anaphylaxis is not going to be an issue for a child with allergic rhinitis. However, with asthma, as we know, the child can go into a really bad bronchial spasm and their airways become so narrowed that they can't breathe at all and they can still die from that.
“For up to 90% of children who have asthma, it's going to be allergic asthma. Up to 16 years old, probably up to 70% of asthma cases are due to allergy and that's still going to be house dust mite allergy.
“Anaphylaxis can be caused by allergy to food, drugs and venom stings from bees, wasps and hornets. These three are the top of the list for allergies that cause anaphylaxis. In children, in some studies, up to 80% of anaphylaxis episodes is due to food allergy. When you think about it and when you compare it to adults, the rate is actually very high,” he says.
In adults, 1-3% of allergies is due to food allergy. In adults, anaphylaxis due to food is probably 30-40%. The majority have unknown causes, but they are still severe life-threatening allergy-like reactions.
How does one confirm an allergy?
Dr Amir says that there are two tests that can be performed to test if the child has specific IgE (Immunoglobulin E). If the result it positive, all it means is that the child is sensitised to the item (such as peanuts). This means that they can potentially develop an allergy to peanuts because they have the specific IgE which one shouldn't have. While the potential is there, that doesn't mean it's a 100% confirmation that they will get that allergy.
The skin prick test – this is done by pricking the child's skin with a series of needles that contain extracts of allergic triggers.
The blood test – the child's blood is sent to the lab for analysis.
Although, the results may come up negative, the child may still show allergy signs. This is where a detailed history of what the child eats, touches and where he goes is important.
Dr Amir explains that parents should only start being concerned and get it checked if the child keeps getting the same allergy symptoms after exposure to the same foods, animals or items in the environment.
“So, then we start to think there is a definite persistent consistent temperal relationship of the allergy-like symptoms.
“I say allergy-like because there are symptoms that look like an allergy but when you do the test, the results are negative.
“It could also be that the blood and skin prick tests are negative but 15 minutes after exposure there are always symptoms. So, the doctor has to look carefully and interpret the results and the history carefully,” says Dr Amir.
What's the point of doing the tests then if they cannot always confirm what a child is allergic to or that he even has an allergy?
“Because by getting a negative result it means that the likelihood of allergy is probably only 2-5%. The gold standard for any food allergy is to do a double-blinded placebo-controlled food challenge test. But that is so cumbersome as both patient and doctor won't know which preparation is the food and which is the placebo. Anyway, in children we don't need to do that. That's just in an ideal situation,” he adds.
Dr Amir admits if parents suspect their child has an allergy they will need to keep track of what the child has eaten, where he has been, what he has come in contact with – a lot of detective work on their part.
He explains that if a child comes in to his clinic and is suspected of having a food allergy, he would have to find out what kinds of food the child eats and even how the food is cooked.
Even if an allergy is confirmed, there is no way for parents or specialist doctors to predict how bad the next allergic reaction will be.
Dr Amir highlights the common cow's milk allergy, for those who are not on breastmilk.
“Here in Malaysia, people tend to switch milk formulas and then go on to soya milk if their child is allergic to cow's milk. Rightly, actually there is a protocol for the cow's milk allergy. They can either go on the high-hydrolysed formula or the amino acid formula, also known as elemental formula; not soya. Soya is an alternative but there are others, too. People need to know that it's not always changing to soya because up to 50% of children with milk allergy can also have soya allergy.
“So they have to be careful and because you cannot predict how bad the next bout of symptoms will be and because even just a small drop can cause a child to not only break out in rashes but could also result in a fit, the child collapsing and going into a shock.
“Unfortunately, parents and doctors sometimes assume you can just change to soya milk, not knowing that they can also cross react and be allergic to the soya as well,” he says.
There is also a risk of misdiagnosis. Often, people tend to not diagnose allergies. They suspect it very strongly but they don't go on to do the tests, assuming it is nothing that could be potentially dangerous and life-threatening.
“Most probably this is because they do not realise how serious it could become if the next reaction is severe.
“Some people say the tests are not accurate, and they're too expensive; but why should all these be excuses? If you think you have diabetes, you do the tests; that's easy enough. There will be some cost to doing an allergy test, moreso because you're testing against a biological thing. But certainly doing the skin prick test is much cheaper than doing the blood test.
“I would recommend that parents bring their children in if the child has allergy-like symptoms consistently. If it's a one-off reaction and isn't consistent enough then you could be excused for not thinking it's an allergy, although it could still be an allergy,” says Dr Amir.
If you suspect your child may have an allergy, then see a doctor and they will find out your child's history of symptoms and then decide if it could be an allergy. If the doctor decides it could be an allergy, you should do the tests to confirm it.
“If you take a good detailed history you will be able to decide. In any medical problem, you find out the history first and from that you can make your diagnosis. It should be accurate 80-85% of the time and when you do the physical examination, you will get the 90-95% accuracy, and the last 5% is the test to confirm it.
“Likewise with allergies. If you suspect it is an allergy but you don't do the last 5% (the tests) to confirm it, you might be avoiding that particular food for no reason. What if the child is not allergic to that and he just avoids that food? Then they come to me all scrawny because they've not had all the nutritional value from the foods they have been avoiding.
“And when I take the history it doesn't really suggest a food allergy and the blood or skin prick test would have shown it to be negative.
“We run into the danger of people who are misdiagnosed, not tested and self-medicating. Sure, you can get away with self-medicating for something like a headache but not if you have allergy-like symptoms and it's too persistent,” says Dr Amir.
Besides the usual antihistamine medication, there is immunotherapy – a “potential” cure.
“I say potential rather than an outright cure because nobody knows why allergy happens in the first place but we understand the mechanism, the intricacies of why the symptoms come about.
“What we do with allergen-specific immunotherapy is we reeducate the immune system to be now tolerant again to the harmless thing. It involves exposing the child to the food he is allergic to over a period of time in incremental amounts,” he says.
This normally takes about three to five years and by that time the body will remember that it is not a harmful food to him.
In the initial period, the child will probably need to have to be on medication because the symptoms may be more then.
This article was first published in www.parenthots.com on 11 July 2011.