Allergies on the rise

Whether it's pollen, wasps, nuts or mites - more and more children are developing allergies. This is how their immune system defends itself. Sometimes a hypersensitivity develops, but it often lasts a lifetime.

Laura is allergic to eggs. «It was dramatic when she reacted for the first time,» says the mum of the almost two-year-old. She gave her vegetable mash with boiled egg for the first time when she was around one year old, which she ate without any problems. She then saw red spots when changing her nappy. «But as Laura has atopic dermatitis, I didn't think much of it,» says Sarah Meier*. A short time later, the girl vomited in gushes. «She was fiery red from top to bottom, with wheals everywhere,» remembers her mother.
Together with her husband, she drove to the paediatric emergency department. Laura was given medication and monitored until the symptoms subsided. An allergist later confirmed the egg allergy. «Laura reacts to the smallest amounts,» says Sarah Meier. The young family's life has become more complicated. Eating out or travelling is difficult. «You wouldn't believe how many places have eggs in them!» says Sarah Meier.

The earlier a child is exposed to viruses and bacteria, the better.

Allergies are on the rise. A recent paper published in the «New England Journal of Medicine» states that allergies to peanuts have doubled in the last ten years. And according to surveys, one in two Europeans will suffer from an allergy in 20 years' time. Many substances can trigger hypersensitivity.

The immune system in defence mode

«An allergy is nothing more than a malfunction of the immune system,» explains Peter Schmid-Grendelmeier, Head of the Allergy Ward at the Dermatology Clinic at the University Hospital Zurich. In an allergic reaction, the immune system works too well: it reacts hypersensitively to harmless substances and fights them.
Genetic components play a role in the development of an allergy. «If the father or mother suffers from an allergy, the risk for the offspring is 30 per cent. If both parents are affected, this can rise to 70 per cent,» emphasises Peter Schmid-Grendelmeier. There is also the hygiene hypothesis: according to studies, children who grow up on a farm or have early contact with their peers have fewer allergies.

The earlier and more frequently young children are exposed to bacteria and viruses, the better it is for the development of their immune system. Because children today live in a hygienic, i.e. low-germ environment, their defence system reacts more strongly to harmless substances.
According to paediatric pneumologist Alexander Möller, the variety of pathogens to which children and their mothers are exposed also plays a role in the development of asthma; this also includes the food that infants eat.

Many unexplained approaches

There are many attempts to explain why allergies are on the rise. «At the moment, allergy research is increasingly focussing on nutrition and the microbiome - i.e. the intestinal flora,» explains Peter Schmid-Grendelmeier. Millions of bacteria from around 1,400 different species live in the gut. «The microbiome influences the immune system, and the diet in turn influences the microbiome,» emphasises the allergy expert.
According to Alexander Möller, this new approach, which has not yet been fully clarified, is particularly relevant for children, as babies are born «sterile». «Colonisation of the intestinal flora only begins after birth.» The way in which the microbiome is built up and the balance or imbalance in the intestinal flora is therefore relevant here.
The question of whether early administration of antibiotics increases the risk of allergies is also being discussed. This is because a new study indicates that antibiotics in the first two years of life can have a lasting effect on the intestinal flora and thus influence the immune system.
Although psychological and physical factors can play a role depending on age, in children it is primarily environmental factors. A major risk factor is when children are exposed to tobacco smoke. This is especially true during pregnancy, in the womb, emphasises Alexander Möller.

Search for allergy triggers

An inherited tendency to allergies can manifest itself as hay fever, asthma, food allergies or neurodermatitis. Affected children can «grow out» of one type of allergy, but then develop the next type of allergy: first atopic dermatitis, then asthma and later hay fever.
The sequence of these three atopic diseases (allergies in which the immune system reacts to the allergen within seconds or minutes) during childhood is often referred to as an «allergy career». Pollen, animal dander, food, house dust mites and insect venom are the most common allergens.

If both parents suffer from allergies, the risk for the children is 70 per cent.

The family history and previous history of allergies are relevant for the diagnosis. «It's about finding out what triggered the allergy,» says Schmid-Grendelmeier. «What were the symptoms and what could be related to the allergen?» The form of the symptoms is also revealing:
Are they attack-like, seasonal or localised? This is how the search for the allergen begins.
There are also various tests for this: skin tests in which various allergens are dripped onto the skin or applied in a plaster. «We choose the type of test depending on the suspected allergen.» Blood analyses are used to determine antibodies, and there are also intranasal (applied in the nose) or inhaled provocation tests. «If asthma is suspected, a lung function test is carried out,» says Alexander Möller. This involves the children breathing into a measuring device that measures the amount of air inhaled and exhaled per unit of time.

Contain reaction and increase tolerance

Allergy treatment involves avoiding allergens (substances that can trigger an allergic reaction) and training those affected to deal with emergency situations. Some allergies require medication containing antihistamines or cortisone. Although these reduce the allergic reaction, they do not combat its causes.
«Asthma often requires an inhalation spray containing cortisone,» says Möller, as children do not get enough oxygen during attacks, which has health consequences. The powder mist distributes the active ingredient in the airways. As the doses are in the micro and nano range, parents do not have to worry about the side effects of cortisone, says Möller. For him, who looks after many children with asthma, there is no compromise when they suffer. «We need a clear diagnosis and if their performance is impaired, we have to treat them.» Asthma often progresses to school age.

Children with allergies should not be marginalised, but should be able to lead a normal life.

According to Professor Schmid-Grendelmeier, one therapy that addresses the causes is desensitisation. «We often start this at school age,» he says. The treatment can be administered by injection, a variant with tablets or drops is also possible and is particularly popular with children. According to both doctors, the long-term effects are very good.
Recent studies also show that contact in infancy with possible allergenic substances such as peanut butter drastically reduces the risk of allergies. Both doctors believe it is important that affected children and their parents receive training. Peter Schmid-Grendelmeier also appeals to teachers: «Children with allergies should not be ostracised, but should be able to lead a normal life!» All carers must take responsibility here.

* Name changed
Image: Juice Images / Alamy Stock Photo

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Risk of allergic shock

Certain allergens can trigger a life-threatening allergic shock. Allergy sufferers should therefore always carry emergency kits with them. Typical symptoms: furry feeling in the mouth with itching, shortness of breath up to severe asthma attacks, reddening of the skin, wheals, vomiting, dizziness, rapid heartbeat and drop in blood pressure up to collapse. This is often characteristic of wasp or bee venom allergies.

Exhalomics research project - early diagnosis and prevention of asthma in children

Asthma is the most common chronic disease in childhood. However, diagnosis at preschool age is almost impossible, which is why many children do not receive adequate treatment. As part of the «Zurich Exhalomics» research project, researchers at the Children's Hospital Zurich are looking for specific biomarkers to enable early detection of asthma.

Further information at www.aha.ch

Allergies - an overview

The causes are often symptoms of an allergic reaction; neurodermatitis is a typical example.
Hay fever is an allergic reaction to pollen and is associated with the flowering phase of trees and cereals. The mucous membranes of the nose and eyes become itchy and swollen. The consequence is allergic asthma.
House dust mite allergy: The excretions of mites can trigger rhinitis or asthma.
Children often develop food intolerances to dairy products, eggs, cereals, fish or fruit.
A latex allergy is a hypersensitivity to the proteins in latex.
Animal allergies are usually directed against cats, dogs, horses and rodents.
Drug allergies are usually triggered by antibiotics, painkillers, anti-seizure drugs and tranquillisers.
Allergens are the most common triggers of bronchial asthma, such as pollen, animal dander, house dust mites and mould.
Many children suffer from sun allergies. The allergy manifests itself as pustules or blisters after the skin has been exposed to the sun.

Prevent allergies

Breastfeed babies for as long as possible, preferably four to six months.
Alternatively, give high-risk children hypoallergenic food for the first four to six months.
From the age of four months, give as many complementary foods as possible.
Stop sterilising baby utensils such as bottles or dummies.
Avoid anything that can promote an allergy, especially smoking!
Do not keep pets in high-risk families.
Wash cuddly toys regularly.
Expose children to bacteria and viruses as early as possible (crèche, toddler group, playgroup, farm visits).
Change of location during the pollen season.
Restraint with the use of antibiotics is recommended.
Have children with asthma vaccinated against whooping cough and pneumococcus.