Food Allergy

Question 1

Define allergic rhinitis/ hay fever

Answer 1

Blocked/ runny nose
Itchy nose
Sneezing
Triggered: pollen, pets, HDM

Question 2

Define allergic conjunctivitis

Answer 2

Red, swollen, itchy, watery eyes

Can occur with allergic rhinitis

Question 3

Define asthma

Answer 3

Chest symptoms wheeze/ cough/ shortness breath/ tight chest

Not always allergic

Question 4

Define atopic dermatitis/ eczema

Answer 4

Commonest chronic inflammatory skin disease

Itch and excoriation

Question 5

What is urticaria (hives)?

Answer 5

Acute/ chronic (+-6w) macula-popular pruritus rash without or with angioedema

Question 6

Different categories of insect allergy

Answer 6

Often bee or wasp

Mild - local
Moderate - urticaria
Severe - anaphylaxis

Question 7

What is allergic conjunctivitis?

Answer 7

Red, swollen, watery, itchy eyes

Question 8

Compare the prevalence of food allergies in children and adults

Answer 8

Children 6%

Adults 2%

Question 9

Why is the most common food allergy in infants? When does it present?

Answer 9

Milk
2-3%
Always presents by 12months
Symptoms can present many weeks after first ingested

Question 10

Two types of presentation of milk allergies

Answer 10

Immediate onset - IgE mediated 40%
Allergy symptoms affecting skin, respiratory and GI tracts
Urticaria, cough, wheeze, vomiting, diarrhoea. Can cause anaphylaxis and be fatal

OR

Delayed onset - non-IgE mediated 60%
Multiple GI symptoms
Difficult to diagnose - younger presentation similar to colic, reflux

Question 11

14 major food allergens

Answer 11

Celery
Cereals contains gluten 
Crustaceans
Eggs
Fish
Lupin - in flour
Milk 
Molluscs
Mustard 
Nuts
Peanuts
Sesame seeds
Soya
Sulphur dioxide (sulphites)

Question 12

Define allergy

Answer 12

Not a disease but mechanism leading to disease
Immunological hypersensitivity can lead to variety of different diseases via different pathomechanisms with different approaches in diagnosis, therapy, prevention can be IgE mediate dor non-IgE mediated

Question 13

Define allergen

Answer 13

Any substance stimulating production IgE or a cellular immune response, usually a protein/ can carbohydrate

Question 14

Hypersensitivity define

Answer 14

Abnormally strong response to a stimulus

Question 15

Define sensitisation

Answer 15

Production IgE antibodies detected by serum IgE assay or skin prick test after repeated exposure to an allergen

Question 16

Define atopy

Answer 16

Tendency produce IgE antibodies in response to ordinary exposure to potential allergens
Strongly associated: asthma, rhinitis, eczema and food allergy

Question 17

Define anaphylaxis

Answer 17

Serious allergic reaction with bronchial, laryngeal and CVS involvement
Rapid onset and can cause death

Question 18

What is a food?

Answer 18

Substance intended for human consumption including drinks and any substance used manufacture, prep or treatment of food

Question 19

Food intolerance meaning

Answer 19

Adverse responses to foods doesn’t involve immune response

Question 20

Food allergy presentation IgE mediated vs non IgE mediated. Symptoms onset, common foods, presenting age, natural history

Answer 20

IgE: immediate 5-30mins, milk/ eggs/ peanuts/ tree nuts/ fish/ shellfish/ fruit/ veg, age of contact, all milk allergies by 1 yr, pFS (f&v) in adolescence, milk/ eggs can resolve, others persist

Non IgE - delayed hrs- days, milk/ soya/ wheat/ rice/ oats, infancy and early childhood, resolve earlier than IgE- many by school age

Question 21

Symptoms in IgE and non IgE mediated allergies skin

Answer 21

IgE: skin - pruritus, erythema, acute urticaria/
angioedema

Non-IgE: priorities, eczema, atopic eczema

Question 22

Symptoms in IgE and non IgE mediated allergies GI

Answer 22

IgE- angioedema, oral pruritus, colicky abdo pain

Non IgE: food refusal/ aversion, abdo pain, infantile colic, gastro-oesophageal reflux disease, loose/ frequent stools, blood/ mucus stools, constipation, perianal redness, pallor, tiredness, faltering growth + GI symptoms +/- eczema

Question 23

Respiratory and CVS symptoms IgE and non IgE

Answer 23

IgE: blocked/ runny nose, sneeze, itch, wheeze, cough, DIB

Pallor, drowsy, hypotension

Non-IgE: none

Question 24

What is food associated exercise induced anaphylaxis?

Answer 24

Food triggers anaphylaxis only if ingestion if followed temporally within 2hrs by exercise

Question 25

What is pollen food syndrome?

Answer 25

Pruritus and mild oedema confined to oral cavity uncommonly progressing, associated with hay fever

Question 26

What is protocolitis

Answer 26

Passage bright red blood in mucous stools in otherwise asymptomatic infants Milk breastfeeding

Question 27

What is enterocolitis

Answer 27

Multiple/ varying GI symptoms include feed refusal, persistent vomiting, abdo cramps, loose/ frequent stools, constipation Milk eggs wheat

Question 28

What is eosinophilic oesophagitis

Answer 28

Symptoms oesophageal inflammation and scarring of feeding disorders, reflux symptoms, vomiting, dysphagia, food impaction Milk eggs wheat

Question 29

What is food protein induced enterocolitis

Answer 29

Primary infants Profuse vomiting leading pallor, lethargy, possible shock, diarrhoea Milk soya rice wheat meat

Question 30

High food allergies tend to present in infancy, early childhood and adolescence?

Answer 30

Infancy - milk, eggs, peanuts Early childhood - soya, wheat, tree nuts, fish, shellfish, kiwi, sesame Adolescence - fresh fruit and veg

Question 31

How can temperature and food matrix effect allergies? Why?

Answer 31

Heating, baking, boiling, canning Can reduce allergens in some ppl, e.g. 70% milk allergic can tolerate baked milk, same with egg Food processing destroys conformational (folded) epitopes

Question 32

Give examples of cross- reactive food allergens

Answer 32

Cows milk - 92% react goats milk Tree nut - 37% react other tree nuts Fish - 50% Shellfish - 75% Pollen - 55% react fruit and veg

Question 33

Steps of evaluating a child with possible food allergy

Answer 33

Medical history - context, symptoms, food considerations Physical exam - manifestations, deferential diagnosis, other allergic conditions Screening test - IgE mediated FA: skin prick, blood specific IgE. IgE and non: elimination diet Diagnosis verification - controlled oral food challenges

Question 34

Essential elements of a medical history in suspected food allergy

Answer 34

``` Age of onset List of all foods suspected Route of exposure Activity at time (exercise/ alcohol) Intercurrent illness (mimic) List of foods previously ingested without symptoms All symptoms & severity Timing symptoms Duration Treatment provided Manner food prepared Minimal quantity of food required to cause symptoms ```

Question 35

How is a typical immunoassay for detection to specific IgE carried out?

Answer 35

Allergen absorbed and immobilised to solid phase Patients serum added -> incubation 30-60mins -> washing steps -> allergen bound IgE detected by enzymatically labelled anti-human IgE monoclonal antibody Most commonly used: ELISA-plates, western blots, strips, immunoCAP, microarrays

Question 36

How can you detect IgE?

Answer 36

Serum specific IgE - circulating in blood OR Skin prick tests - response mast cells Determine presence of sensitivity Level of sIgE/ size SPT correlates with likelihood of allergy (positive predictive thresholds developed for common allergens)