Food allergy and anaphylaxis

Question 1

What is allergy?

Answer 1

• The response of the body’s immune system to normally harmless substances
• Result in symptoms ranging from itch to anaphylaxis

Question 2

How is allergy scientifically defined?

Answer 2

• Variety of different diseases
• From immunologically-mediated and allergen specific hypersensitivity
• Seen in almost every organ, but particularly in skin and mucous membranes
• Leading to different diseases via different pathomechanisms
• With different approaches to diagnosis, management and prevention

Question 3

Define atopy

Answer 3

• Personal and/or family tendency to produce IgE
• In response to ordinary exposure to potential allergens, usually proteins
• Strongly associated with asthma, eczema , hay fever, food allergies

Question 4

Why is allergy important?

Answer 4

• Common
• Associated with significant morbidity - reduce productivity, absenteeism, anxiety, social isolation/exclusion
• Fatal

Question 5

Define allergen

Answer 5

• Any substance stimulating the production of IgE or a cellular immune response
• Usually proteins but can be carbohydrates

Question 6

Define sensitivity vs hypersensitivity

Answer 6

• Sensitivity is normal response to a stimulus
• Hypersensitivity = objectively reproducible symptoms/signs following exposure to a defined stimulus usually tolerated by others

Question 7

Define sensitisation

Answer 7

• Production of allergen specific IgE after repeated allergen exposure
• Sensitisation to an allergen is not synonymous with allergy

Question 8

Define anaphylaxis

Answer 8

• A serious allergic reaction (with laryngeal, bronchial and/or cardiovascular involvement
• Rapid onset
• Can cause death

Question 9

Outline the steps that lead to silent sensitisation

Answer 9

• Clinical picture - no symptoms suggesting immediate onset allergy
• Despite current sensitisation, IgE without corresponding clinical picture

Question 10

Outline the steps that lead to allergy

Answer 10

• Clinical picture - symptoms suggestive of immediate type allergy
• Specific IgE with corresponding clinical symptoms

Question 11

What are the symptoms and triggers of allergic rhinitis?

Answer 11

• Blocked/running nose, sneezing and itching
• Triggers of pollens, pets and house dust mites

Question 12

What are the symptoms and triggers of allergic conjunctivitis?

Answer 12

• Red, itchy, swollen and watery eyes
• Triggers of pollens, pets and house dust mites

Question 13

What are the symptoms and triggers of allergic asthma?

Answer 13

• Wheeze, cough, DIB, exercise symptoms
• Possible triggers of pollens and moulds

Question 14

What are the symptoms and triggers of eczema?

Answer 14

• Dry skin with pruritic inflammation
• Allergy triggers rare, especially food

Question 15

What are the symptoms and triggers of urticaria?

Answer 15

• Acute/chronic (+/- 6 weeks) maculo-papular (hives) pruritic rash +/- swelling
• Chronic spontaneous

Question 16

What are the symptoms and triggers of insect allergy?

Answer 16

• Reaction to wasp or bee sting
• Can be local sting, or large
• Local reaction or systemic

Question 17

What are the symptoms and triggers of drug allergy?

Answer 17

• Commonest culprits are antibiotics (beta lactams) and analgesics (NSAIDs)
• Need confirming

Question 18

What are the symptoms and triggers of food allergy?

Answer 18

• Wide range of potential trigger foods, but mostly eggs, milk and nuts
• Wide presentation

Question 19

Define food allergy

Answer 19

• An abnormal immunological response following exposure (usually ingestion) to food
• Multiple types of food allergy, each with distinct clinical and pathophysiologic features

Question 20

Define food intolerance

Answer 20

• Numerous suspected adverse responses to foods that do not involve the immune system

Question 21

What are some types of non-immune mediated adverse food reactions?

Answer 21

• Food characteristics: pharmacologic (caffeine) and toxic
• Host characteristics: metabolic (e.g. lactose intolerance) and psychological ( e.g. anxiety, food aversion)

Question 22

Give examples of IgE immune mediated adverse food reactions

Answer 22

• Acute urticaria/angioedema
• Anaphylaxis
• Pollen-food syndrome
• Food-associated-exercise-induced anaphylaxis

Question 23

Give examples of non-IgE mediated adverse food reactions

Answer 23

• Proctocolitis
• Enterocolitis
• Eosinophilic oesophagitis
• Food protein induced enterocolitis syndrome (FPIES)

Question 24

Compare the symptom timing of IgE mediated vs non-IgE mediated adverse food reactions

Answer 24

• IgE mediated: 5-30 minutes (max 2 hours)
• Non-IgE mediated: delayed - hours to days

Question 25

Compare the food allergens of IgE mediated vs non-IgE mediated adverse food reactions

Answer 25

• IgE-mediated: cow’s milk, eggs, peanuts, tree nuts, sesame, fish, shellfish, fresh fruit
• Non-IgE mediated: milk, soya, wheat, rice, beef poultry

Question 26

Compare the presenting age of IgE mediated vs non-IgE mediated adverse food reactions

Answer 26

• IgE-mediated: varies depending on age when eaten. In milk allergy all <1 year (older than non-IgE)
• Non-IgE mediated: early contact ages to trigger foods. Milk allergy <3mo.