A paediatrician on common allergies in kids
According to DR LIEW WOEI KANG, who specialises in allergies, immunology and rheumatology, this inflammatory skin disease, which is often characterised by itchy skin and rash, affects 10 to 20 percent of children, especially infants. Subtypes include seborrheic eczema (cradlecap), irritant eczema and atopic eczema. General management includes avoidance of triggers, frequent moisturising and topical anti-inflammatory medications, he says.
#2 FOOD ALLERGIES
Food allergies affect five to eight percent of children, says Dr Liew. “The most common food allergens include eggs, cow’s milk, peanuts, soy, wheat, fish and shellfish in young children. Most of these allergies are outgrown with time, but some persist into later childhood. Food allergens that particularly affect older children and adults include peanuts, tree nuts and shellfish.” Treatment for food allergies is typically strict avoidance, while oral immunotherapy in the form of regular baked or cooked food may be suitable in some instances, he explains.
A chronic respiratory condition in which the airway to the lungs spasms, asthma affects up to 20 percent of children, and usually causes coughing, wheezing, shortness of breath and chest tightness. “The most common type is viral-induced asthma, or ‘childhood asthma’, where wheezing is triggered by respiratory tract viral infections. This tends to be outgrown with time as immunity improves,” says Dr Liew. “In these cases, the wheezing is secondary to recurrent respiratory tract infections; so, when the immunity matures with time, the reduced frequency of respiratory tract infections leads to less irritation to the respiratory tract, allowing for complete recovery of bronchial hyperactivity.”
There’s also allergic asthma, which is associated with environmental allergens, especially house dust mites, pets, cockroaches, mould or pollen. “The respiratory allergies are treated with allergen avoidance, and the use of bronchodilators like Ventolin, and preventers like montelukast and inhaled corticosteroids. Sublingual immunotherapy, where the patient is given small doses of an allergen under the tongue, can also be considered for persistent cases,” says Dr Liew.
#4 ALLERGIC RHINITIS
This type of inflammation in the nose occurs when the immune system reacts to allergens, resulting in a stuffy or runny nose, sneezing, itchy and watery eyes. According to Dr Liew, allergic rhinitis affects 20 to 30 percent of children, and is often associated with allergic conjunctivitis (eye inflammation). He says the causes and treatment are similar to those of allergic asthma. Dr Liew also notes that hay fever, which is a type of allergic rhinitis, is usually a seasonal allergy to grass pollen, while perennial allergic rhinitis here in Singapore is usually due to house mite allergies. Dr Liew adds, “Allergic rhinitis can improve with age, as many exacerbations in young children are secondary to recurrent infections. The more optimal the control of the respiratory allergies, the more likely the child will have a good outcome, including having optimal lung function in adulthood.”
Prevalence and progression
While the commonness of asthma and allergic rhinitis has remained stable, the pervasiveness of food allergies and atopic eczema has increased in recent years.
“We don’t know why the prevalence of atopic eczema and food allergies is increasing, but reasons could include environmental pollution, modifications of food sources and the environment being too hygienic, making the immune system more skewed towards allergies,” says Dr Liew.
And, while some allergies can be outgrown, if there’s a family history of allergy then there’s a possibility that a child may develop other allergies. The most important thing, Dr Liew says, is to get the right diagnosis in order to manage things correctly.
“Patients with asthma require a special highlight, as food allergies are more dangerous if the underlying asthma is not diagnosed or optimally controlled. This is one of the main reasons why food anaphylaxis can lead to fatalities, something we see reported around the world.”
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