Allergies

Question 1

What are allergies?

Answer 1

• Hypersensitive disorder of the immune system
• Allergic reactions occur to normally harmless environmental substances known as allergens; these reactions are acquired
○ Usually proteins
○ Depending on the individual, allergen and mode of introduction, symptoms systemic or localised
○ e.g. asthma to respiratory system and eczema to dermis

Question 2

What are the different types of allergies?

Answer 2

○ Skin: Utica (hives)/ angioedema (swelling)
○ Upper respiratory: rhinitis
○ Lower respiratory: asthma
○ Systemic: anaphylaxis

Question 3

What are the risk factors for allergies?

Answer 3

○ Host factors: heredity, race and age
○ Environmental factors: alterations in exposure to infectious diseases during early childhood, environmental pollution, allergen levels, and dietary changes
○ Occupational: flour, latex, wood dust

Question 4

What are the symptoms of allergies?

Answer 4

○ Intermediate: sneezing, itch, nasal blockage, rhinorrhoea

○ Late: chronic obstruction, hyposmia, hyperreactivity

Question 5

What is the pathophysiology of type 1/ intermediate hypersensitivity reaction?

Answer 5

○ Sensitisation
- Plasma cells produce IgE
- Bind to mast cells
○ Re-exposure
- Mast cells degranulate
- Release histamine, leukotrienes, prostaglandins and chromatic factors
□ Vasodilation, vascular permeability, smooth muscle contraction, leukocyte infiltration, especially eosinophils

Question 6

What is the pathophysiology to the acute response?

Answer 6

○ Exposure to allergen
○ Ag+ specific IgE
○ Degranulation with release of histamine, cytokines, interleukins, leukotrienes, and prostaglandins from their granules causing systemic effects, such as vasodilation, mucous secretion, nerve stimulation and smooth muscle contraction.

Question 7

What is the late phase response?

Answer 7

○ 2-4 hours
○ This is due to the migration of other leukocytes such as neutrophils, lymphocytes, eosinophils and macrophages to the initial site.

Question 8

What are the factors which produce an allergic reactions?

Answer 8

• Asthma (9.4%)
• Allergic rhinitis (5.4%)
○ allergic inflammation of the nasal airways
○ Occurs when allergen is inhaled by an individual with a sensitized immune system
• Eczema (1%)
• Food allergies (1-2%)
• Multiple allergies (3.7%)

Question 9

What are the classifications of allergic rhinitis?

Answer 9

• Mild persistent
• Mild intermittent
• Moderate-severe persistent
• Moderate-severe intermittent

Question 10

What are the requirements of mild allergic rhinitis

Answer 10

• normal sleep
• No impaired daily activity, sport, leisure
• No impairment of work or school
• Symptoms present but not bothersome

Question 11

What are the requirements of moderate-severe rhinitis?

Answer 11

One of the following:

• Disturbed sleep
• Impaired daily activity, sport, leisure
• Impairment of work or school
• Bothersome symptoms

Question 12

Explain skin tests

Answer 12

responses to known allergens- high NPV, up to 15% false positives

Question 13

What does RAST test for?

Answer 13

presence and levels of allergen-specific IgE

Question 14

What blood tests can be done in regards to allergies?

Answer 14

○ Total Serum IgE
○ Nasal Allergen Challenge
○ Nasal Cytology

Question 15

How can one manage allergies?

Answer 15

• Allergen avoidance- Education
• Pharmacotherapy
○     Topical Intranasal steroids
○     Systemic Steroids
○     Antihistamines
○     Sodium Cromoglycate
○     Allergen Immunotherapy
○     Anti-IgE
• Immunotherapy