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What is allergy?

Definition of allergy

  • A misguided reaction to foreign substances by the immune system, the body system of defense against pathogens
  • The allergic reaction is misguided in that these foreign substances are usually harmless
  • The substances that trigger allergy are called allergen
  • Examples include pollens, dust mite, moulds, animal dander and certain foods.
  • People prone to allergies are said to be allergic or atopic

Mechanism of allergic reaction

  • Prevalence of allergic disease
  • Food allergy: Classification
  • Clinical presentation of food allergy
  • Diagnosis of food allergy
  • Treatment of food allergy
  • Asthma
  • Allergic rhinitis
  • Eczema
  • Prevalence of allergic disease
  • Food allergy: Classification
  • Clinical presentation of food allergy
  • Diagnosis of food allergy
  • Treatment of food allergy
  • Asthma
  • Allergic rhinitis
  • Eczema

Allergy epidemic

  • Most common long-term condition in UK children
  • 39% children diagnosed with allergic disease
  • 12.5 million GP visits per year
  • Annual cost to the NHS exceeds £1 billion

Food allergy rates in young children

How common is allergic rhinitis?

Allergic reaction in a child

Clinical presentation

  • Most food-induced allergic reactions occur on first known oral exposure
  • Especially in the case of eggs and peanuts
  • Most likely in children with a history of severe, early onset eczema

Clues to food allergy in eczema

  • Atopic family history
  • Early onset of eczema
  • Severity of eczema
  • Resistant to treatment
  • Gastrointestinal symptoms
  • Faltering growth

Medical history in a workup for food allergy

Medical history in a workup for food allergy

Secondary care referral

IgE mediated symptoms

  • Anaphylaxis
  • IgE mediated food allergy and concurrent asthma
  • Possible multiple food allergies
  • Strong clinical suspicion despite negative tests

Non IgE mediated symptoms

  • Faltering growth and gastrointestinal symptoms
  • Symptoms do not respond to single elimination diet
  • Significant eczema where multiple food allergies are suspected
  • Persistent parental suspicion of food allergy despite lack of supporting history

In vivo tests

In vitro tests

Food challenge test

Management Principles

  • Allergen avoidance
  • Recognition & treatment of reactions
    Parental and child education
    Management in school
    Follow up
  • Asthma control

Allergen avoidance

  • Can’t be overemphasized
  • Most severe reactions occur in known food allergy, where food accidentally eaten in commercially prepared food
  • Most reactions occur at home but 20% in school
  • Paediatric dietician is central

Food labelling

  • 2004 EU regulations to draw attention to presence of 14 allergens
  • Foreign foods
  • Cross contamination
  • Restaurants/takeaways

EU 2004 labelling

  1. Cereals containing gluten (i.e. wheat, rye, barley, oats, spelt, kamut)
  2. Crustaceans
  3. Eggs
  4. Fish
  5. Peanuts
  6. Soybeans
  7. Milk (including lactose)
  8. Nuts
  9. Celery
  10. Mustard
  11. Sesame seeds
  12. Sulphur dioxide and sulphites (> 10 mg/kg)
  13. Lupin
  14. Molluscs

Recognition and treatment

  • Educate all family members and carers (including school staff)
  • Written treatment plan
  • Stress early treatment
  • Carry medications all the times
  • Medicalert
  • Planning eg overseas travel

The management of anaphylaxis in childhood: position paper of the European academy of allergology and clinical immunology

Cross-Reactivity between Common Food Allergens

Natural History of Food Allergy

Asthma Control

  • Approximately 50% of children with food allergy will wheeze
  • Active asthma is the major risk factor for severe allergic reactions
  • Almost every recorded child death from food allergy also had poorly controlled asthma

Allergic asthma

  • Allergic asthma is the most common form of asthma
  • Many of the symptoms of allergic and non-allergic asthma are the same
  • However, allergic asthma is triggered by inhaling allergens

Allergen exposure and asthma

Allergen avoidance

  • HDM reduction measures to prevent asthma – NO
  • HDM reduction measures in HDM sensitized individual for symptom relief:
  • Asthma – NO
  • Perennial allergic rhinitis – YES (extensive only)
  • Pet dander control for allergic asthma
  • No trials on pet allergen reduction or rehousing – ?

Asthma Management

Asthma in the UK

  • UK rates of wheeze 2-3 times higher than rates in Europe, but mortality is 5-10 times higher
  • Emergency admission rate for asthmatic children 26-642/100,000 (25-fold variation) in 2012

NRAD – 195 deaths 2012-2013

  • Excessive prescription of reliever medication
  • Inadequate prescription of preventer medication
  • Inappropriate prescribing of LABAs
  • 23% had personalised asthma action plan (PAAP)
  • Use of PAAP reduces risk of hospital admission 4-fold

NRAD – 18 deaths in children

  • Majority of children dies before reaching hospital
  • 8 out of 10 (80%) aged <10 years
  • 13 out of 18 (72%) aged 10 – 19 years
  • 43% were managed only in primary care
  • 78% aged 10-19 years died between March-Sept
  • 39% had known allergic comorbidities

NRAD Recommendations

  • PAAP in all children
  • Details of asthma triggers
  • Current asthma treatment
  • What to do in exacerbation and how to seek help
  • Review at least annually
  • Inhaler technique training
  • Compliance with preventer treatment
  • Minimise exposure to allergens and smoke
  • 12 reliever prescription should trigger urgent review
  • How, why and when they should use asthma medication

Allergic rhinitis and asthma

  • Asthma is increased in allergic rhinitis
  • 19–38% AR vs. 3–5% general population
  • Allergic rhinitis almost always present in asthma
  • 78% asthmatics vs 20% general population
  • AR increases asthma severity risk
  • 3-fold risk of frequent wheezing attacks
  • 10-fold risk of frequent GP visits for asthma

Allergic rhinitis

Common causes of Allergic Rhinitis

  • Grass pollen
  • April-September
  • Tree pollen
  • February-May
  • Perennial allergens
  • House dust mite
  • Animals

ARIA Classification of allergic rhinitis

Treatment of allergic rhinitis


Emollients: 500g/week

Take home messages

  • Think of food allergy in child with early onset severe eczema
  • Differences between IgE and non IgE mediated food allergy
  • Stress early use of adrenaline autoinjector if breathing difficulties or lethargic
  • Children with food allergy need optimum treatment of their asthma

Take home messages

  • Look for allergic rhinitis in children with asthma
  • All children with asthma should have a personalised asthma action plan
  • Most effective treatment for allergic rhinitis is intranasal steroid spray (used correctly)
  • In children with eczema use 500g emollient/week