Allergy

Question 1

What is atopy?

Answer 1

Personal and/or family tendency to produce IgE antibodies in response to ordinary exposures to potential allergens, usually proteins
Strongly associated with asthma, allergic rhinitis and conjunctivitis, eczema and food allergy

Question 2

Eczema

Answer 2

Atopic or non-atopic
Atopic = evidence of IgE antibodies to common allergens, classed as an allergic disease
Many children have a FHx of allergy
Close relationship with food allergy (in particular egg allergy)
Screening by skin prick or IgE blood testing considered

Question 3

Allergic rhinitis and conjunctivitis

Answer 3

Atopic or non-atopic
Underestimated cause of childhood morbidity
Intermittent or persistent and mild or severe
Temperate climates often classified as seasonal (grass, weed or tree pollen) or perennial (house dust mites and pets)
Associated with eczema, sinusitis and adenoidal hypertrophy, closely associated with asthma

Question 4

Mechanism of allergic disease

Answer 4

polymorphisms or mutations in certain genes linked to development of allergic disease lead to susceptibility to allergy
Allergic reaction occurs when individuals make an abnormal immune response to harmless environmental stimuli, usually proteins
Developing immune system must be ‘sensitised’ to an allergen before an allergic immune response develops - sensation can be ‘occult’ meaning that sensitisation can happen even when trace amounts of food are ingested

Question 5

Main stimuli for allergens

Answer 5

Inhalant allergens - house-dust mite, plant pollens, pet dander, moulds
Ingestant allergens - nuts, seeds, legumes, cow’s milk, eggs, seafood, fruits
Insects stings/bites, drugs and natural rubber latex

Question 6

IgE mediated allergic reactions (phases)

Answer 6

Early phase: within minutes of exposure to allergen
- release of histamine etc from mast cells
- cause of urticaria, angioedema, sneezing and bronchospasm

Late phase occurring after 4-6 hours:
- causes nasal congestion in upper airway, cough and bronchospasm in lower airway

Question 7

Allergic march

Answer 7

Allergic children develop individual allergic disorders at different ages:
- eczema and food allergy usually develop in infancy (often both are present) - presence is predictive of asthma and allergic rhinitis later in life
- allergic rhinitis, conjunctivitis and asthma occur most often in preschool and primary school years
- rhinitis and conjunctivitis often preceed development of asthma

Question 8

Allergy Mx:

Answer 8

Allergy is considered a systemic disease - identify triggers to avoid and to manage children with multi-system or severe disease
Specific allergen immunotherapy can be used for allergic rhinitis, conjunctivitis, insect stings, anaphylaxis and asthma
Solutions of allergen are injected subcut or sublingual on a regular basis for 3-5y to develop immune tolerance
sublingual is safer