Session 2 - Food Allergy Flashcards by Emma Williamson

What is an allergy?

Is not a disease itself but a mechanism leading to disease.
Immunological hypersensitivity that can lead to a variety of different disease via different pathomechanisms with different approaches in diagnosis, therapy and prevention.

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What is an allergen?

Any substance stimulating the production of IgE or a cellular immune response. Usually a protein but can be carbs.

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What is sensitivity?

Normal response to a stimulus

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What is hypersensitivity?

Abnormally strong response to stimuli

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What is sensitisation?

Production of IgE antibodies (detected by serum IgE assay or SPT) after repeated exposure to an allergen.

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What is atopy?

A tendency to produce IgE antibodies in response to ordinary exposure to potential allergens. Strongly associated with asthma, rhinitis, eczema and food allergy.

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What is anaphylaxis?

A serious allergic reaction with bronchial, laryngeal and cardiovascular involvement that is rapid in onset and can cause death.

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What is food?

A substance whether processed, semi-processed or raw, which is intended for human consumption (including drinks), and any substance used in the manufacture, preparation or treatment of food.

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What is a food allergy?

Immunologically mediated adverse reaction to food

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What are the major allergic reactions?

Allergic rhinitis (hay fever) 
Allergic conjunctivitis 
Asthma 
Atopic dermatitis/eczema 
Urticaria (Hives) 
Insect allergy 
Drug allergy 
Food allergy

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How does allergic rhinitis (hay fever) present.

Blocked/runny nose, itchy nose, sneezing. Trigggered by pollen, let’s or HDM.

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What is allergic conjunctivitis?

Red, swollen, itchy, watery eyes. Can occur with allergic rhinitis.

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What is asthma?

Chest symptoms of wheeze, cough, shortness of breath and tight chest. Not always allergic.

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What is atopic dermatitis/eczema?

Commonest chronic inflammatory skin disease with itch and excoriation

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What is urticaria/hives?

Acute/chronic macula-papular pruitic rash without or with angioedema

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What is an insect allergy?

Mainly to bee or wasp stings. Mild (local), moderate (urticaria), severe (anaphylaxis).

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What is a food allergy?

Clinically broad symptom spectrum varying in timing of presentation and in severity.

Name some key facts relating to milk allergy.

commonest food allergy in infants
always presents by 12 months of age
symptoms can present many weeks after first ingested

What are the 2 types of presentation of a milk allergy?

1) immediate onset IgE mediated:
- typical allergy symptoms affecting skin, Resp, and Gi tracts.
- symptoms of urticaria, cough, wheeze, vomiting, diarrhoea
- can cause anaphylaxis and even be fatal

2) delayed onset, non IgE mediated:
- predominantly multiple GI systems
- difficult to diagnose, younger presentation similar to colic reflux

What are the major food allergens?

Celery 
Cereals containing gluten 
Eggs 
Fish 
Milk 
Mustard 
Nuts 
Peanuts 
Sesame seeds 
Soya

Define food intolerance.

Numerous (frequently reported) adverse responses to foods that do not involve an immune response

What are the IgE mediated Adverse food reactions?

acute urticaria/angioedema
anaphylaxis
pollen food syndrome
food associated exercise induced anaphylaxis

What are the non-IgE mediated Adverse food reactions?

proctocolitis
enterocolitis
eosinophillic oesophagitis
food protein induced enterocolitis syndrome (FPIES)

What is the difference in Symptom onset betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = immediate 5-30 min

Non IgE mediated = delayed = hours to days

What is the difference in common foods betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = milk and eggs, peanuts and tree nuts, fish and shell fish, fruit and vegetables Non IgE mediated = milk and soya, wheat, rice, oats

What is the difference in presenting age betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = variable (age of contact), all milk allergy by 1 year, OSF in adolescence Non IgE mediated = infancy and early childhood, all milk allergy by 1 year

What is the difference in natural history betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = milk and egg allergy can resolve, others persistent into adulthood Non IgE mediated = resolve earlier than IgE, many by school age

What is the difference in skin presentation betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = pruitus, erythema, acute urticaria (localised or generalised), acute angioedema (most commonly of the lips, face and around the eyes) Non-IgE mediated = pruitus, eczema, atopic eczema

What is the difference in gastrointestinal system presentation betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = angioedema Of lips, tongue and palate, oral pruitus, nausea, vomiting, diarrhoea, colicky abdominal pain Non IgE mediated = food refusal, abdominal pain, GORD, loose/frequent stool, blood/mucus in stool, constipation, perinatal redness, pallor and tiredness, faltering growth with at least 1 or more of GI symptoms

What is the difference in respiratory system presentation betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = blocked/runny nose, sneeze, itch, wheeze, cough, DIB None

What is the difference in cardiovascular system presentation betweeen IgE mediated and non IgE mediated food allergy presentation?

IgE mediated = pallor, drowsy, hypotension None

What are the essential elements of a medical history in suspected food allergy?

Context Symptoms Food

When taking a history for a food allergy what would be covered in context?

Thorough description of reaction: - age of onset - complete list of all suspected foods causing symptoms - route of exposure - activity at time of exposure (exercise or alcohol can potential reaction) - any intercurrent illness at time of reaction (can mimic allergic reaction) - list of foods previously ingested without symptoms

When taking a history for a food allergy what would be covered in symptoms?

- all observed symptoms and each ones severity - timing of symptom onset in relationship to food exposure - duration of symptoms, treatment provided and response to treatment

When taking a history for a food allergy what would be covered in food?

- manner in which food was prepared (cooked, raw, added ingredients) - minimal quantity of food exposure required to cause symptoms

What are the treatment options of managing a food allergy?

- appropriate assessment - dietary advice - medical advice

What is appropriate assessment in relation to food allergy management?

- allergy focussed history and examination | - appropriately selected allergy investigations = identify food causing symptoms

What is dietary in relation to food allergy management?

- exclusions = which food/food groups/ food formats to avoid - inclusion = which food/groups/ formats not to avoid - label reading = ingredient labelling, patient advisory labels - food reintroduction

What is medical advice in relation to food allergy management?

- emergency management of allergic/anaphylactic reaction

How is a milk allergy managed?

Selection of replacement infant formulas: - extensive hydrolysed formula - amino acid formula - soya - dairy free weaning advice followed by milk introduction

Describe the lactase evolution and action.

- detectecion from 8 weeks gestation, rise from 32 weeks to peak at birth - activity decreases within months - present on menu all brush border apex - hydrolysis Of lactose into mono-saccharides galactose and glucose

What is lactose intolerance?

- occurs in most humans (variable) - typical symptoms = bloating, flatulence, explosive diarrhoea - onset = subtle, progressive years - most diagnosed as adolescent or adult - not always symptomatic with milk