Food Allergy Flashcards
What are the 2 different types of food allergy?
It can be classified into IgE-mediated and non-IgE-mediated reactions
What are the signs and symptoms of IgE mediated food allergy?
IgE possible food allergy:
- Skin: pruritus, erythema, acute urticaria and acute angioedema
- GI: angiodema of the lips, tongue and palate, oral pruritus, nausea, colicky abdominal pain, vomiting and diarrhoea
- URT symptoms: nasal itching, sneezing, rhinorrhoea or congestion
- LRT symptoms: cough, chest tightness, wheezing or shortness of breath
- Other: signs or symptoms of anaphylaxis or other systemic allergic reactions
What are the signs and symptoms of non-IgE mediated food allergy?
Non-IgE possible food allergy:
- Skin: pruritus, erythema and atopic eczema
- GI: GORD, loose or frequent stools, blood and/or mucus in stools, abdominal pain, infantile colic, food refusal or aversion, constipation, perianal redness, pallor and tiredness and faltering growth
- LRT symptoms: cough, chest tightness, wheezing or shortness of breath
Which type of food allergy (IgE or non-IgE) is acute?
IgE-mediated reactions are acute and frequently have a rapid onset.
Non-IgE-mediated reactions are generally characterised by delayed and non- acute reactions.
What is food intolerance?
Food intolerance is a non-immunologically mediated adverse reaction to food. It includes:
- Enzyme deficiencies e.g. lactase deficiency
- Pharmacological e.g. tachycardias in heavy tea/coffee drinkers due to caffeine
- Sensitivity to vasoactive amines in food, causing localized reactions such as lip swelling e.g. cured meats, cheeses, fish, ripe bananas, oranges, tomatoes and strawberries
- Toxin-mediated e.g. scrombroid poisoning (histamine from spoilt fish) and food poisoning
- Chemical effects (gustatory rhinitis with hot/spicy foods)
- Irritant reactions
- Infectious syndromes e.g. food poisoning or acute urticaria with viral illness
Briefly describe the history taking of food allergy
Careful history taking is important in a diagnosis of allergic disease, because it helps to differentiate allergic from non-allergic reactions, to identify potential triggers, and to direct investigations.
- Presenting symptoms
- Focus on gut, skin, and respiratory systems to differentiate IgE from non-IgE-mediated reactions
- Timing of the reaction from ingestion
- Previous exposure to the allergen and severity of reactions
- Detailed feeding history, including breastfed/bottle-fed; weaning; foods avoided and why
- Exposure to other common allergens
- Whether the reaction was preceded by exercise, viral illness or alcohol consumption
- History of other atopic diseases, including infantile eczema, asthma, and allergic rhinitis
- Family history of atopy
What are the common food allergies in children?
- Cow’s milk
- Egg
- Peanuts
- Wheat
- Soya
- Tree nuts e.g. hazelnut, cashew, almond and walnut
- Sesame
- Other legumes e.g. beans, lentils, chickpeas and peas
Briefly describe the diagnosis of IgE mediated food allergy
Based on the results of the allergy-focused clinical history, if IgE- mediated allergy is suspected, offer the child or young person a skin prick test and/or blood tests for specific IgE antibodies to the suspected foods and likely co-allergens.
Briefly describe the diagnosis of non-IgE mediated food allergy
There is no single diagnostic test for non-IgE-mediated food allergy:
- Use a 4wk exclusion period and assess symptom resolution
- Then re-introduce any of the suspected allergens into the diet, even if improvement in symptoms is seen
- Allergy is then confirmed and diagnosed if symptoms recur
Briefly describe the management of food allaergy
Key to initial management is dietary exclusion of the allergenic food. Practical, individualised advice should be provided on allergen avoidance and dietary alternatives:
- Levels of exclusion depend on the child; some children may tolerate trace amounts or a cooked form (e.g. baked egg or milk)
- Parents, carers, and children should be educated on allergen avoidance, allergy recognition and treatment
- A written personal management plan should be provided
- Children with multiple food allergies or young children with cow’s milk allergy should have dietetic input to avoid nutritional deficiencies
- Monitor growth as children with multiple food allergies are at risk of nutritional deficiencies
- Ensure antihistamines are prescribed and assess the need for an adrenaline autoinjector
Briefly describe the advice surrounding ‘may contain’ food labels
Simple rules to help risk-assess these food labels are:
- Check the product every time as ingredients can change
- Particularly avoid ‘may contain’ products when unwell (illness lowers the threshold for anaphylactic reactions)
- Only consume these foods when able to easily access help
- Only consume these foods when rescue medication is available
- Do not consume these foods if a previous severe (anaphylactic) reaction has occurred to the index food
- Do not consume if suffering from uncontrolled asthma
Briefly describe the prognosis of various food allergies
Milk, egg, wheat, and soy allergies are most likely to be outgrown.
Eighty per cent of milk and 60% of egg allergies will resolve by age 5y, so yearly follow-up is appropriate.
For peanuts and tree nuts, resolution rates are lower (20% by age 5y), so follow-up every 2–3y is sufficient.
Briefly describe the follow up of food allergies
Follow-up should be focused around key transition points, e.g. school changes, teenage years.
- At follow-up, review if any accidental exposure has occurred and any reaction confirming ongoing allergy
- Review the need for medications and retrain in adrenaline autoinjector use if needed
- Assess and optimize management of associated conditions e.g. eczema and asthma
- Egg allergy and immunisation
Briefly describe the advice surrounding egg allergy and immunisations
All egg-allergic children can be immunized with MMR (measles, mumps, and rubella) vaccine in primary care.
Seasonal influenza vaccine is safe for egg-allergic children, except those with anaphylaxis to egg which required intensive care. It can be administered in primary care or schools.
Children with severe anaphylaxis to egg should be referred to hospital for vaccination with an inactivated vaccine with very low ovalbumin content.
Yellow fever vaccine is indicated in all, except if there is a history of anaphylaxis to egg.
Briefly describe allergy resolution for both non-IgE and IgE mediated food allergy
For non-IgE-mediated allergy, re-introduction can occur at home, using a staged plan.
For IgE-mediated allergy where resolution is suspected (no history of reactions and significant reduction in specifc IgE/SPT), a hospital-based oral food challenge should usually be undertaken as the risk of anaphylaxis is higher.
Briefly describe the iMAP milk ladder for home re-introduction of milk
