Food allergy Flashcards
What is an allergen?
Any substance stimulating the production of IgE or a cellular immune response. Usually a protein, but can be carbohydrates (much less common).
What is sensitivity?
Normal response to a stimuli
What is hypersensitivity?
Abnormally strong response to a stimulus
What is sensitisation?
Production of IgE antibodies (detected by serum IgE assay or SPT) after repeated exposure to an allergen
What is an allergy?
A hypersensitivity reaction initiated by specific immuno- logical mechanisms. This can be IgE mediated (e.g. peanut allergy) or non-IgE mediated (e.g. milk allergy)
What is atrophy?
A tendency to produce IgE antibodies in response to ordinary exposure to potential allergens. Strongly associated with asthma, rhinitis, eczema and food allergy.
What is anaphylaxis?
A serious allergic reaction with bronchial, laryngeal and cardiovascular involvement that is rapid in onset and can cause death.
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
What is a food allergy?
Immunologically mediated adverse reaction to food
What are the symptoms for allergic rhinitis? (hay fever)
Blocked or runny nose
itchy nose
sneezing
triggered by pollen, pets or HDM
How does allergic conjunctivitis present?
Red, swollen, itchy watery eyes, may occur with hay fever
How does asthma present?
Chest symptoms of wheeze, cough, shortness of breath and tight chest pain
only sometimes allergic
How does atopic dermatitis eczema?
Commonest chronic inflammatory skin disease with itch and excoriation
How does urticaria present?
Acute/chronic (±6w) maculo-papular pruritic rash without or with angioedema
How does insect allergy present?
bee or wasp mainly
mild-local
moderate-urticaria and severe- anaphylaxis
How does drug allergy present?
e.g. antibiotics
only minority who are labeled drug allergic are actually allergic
How does food allergy present
broad spectrum varying in timing of presentation and severity
Can children grow out of eczema, hay fever and food allergy ?
Yes
What is the allergy of adult hood?
Hayfever
How many UK adults suffer from at least one allergy?
1/2
How can an allergy cause disruption to life?
symptoms and impaired sleep reduces productivity
recurrent hospital admissions and restrictive diets cause social exclusion
fatal
What is a food allergy?
An adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a food. Definition encompasses immune responses that are IgE- mediated or non-IgE mediated.
What is food intolerance?
Numerous (frequently reported) adverse responses to
foods that do not involve an immune response.
What is prevalence?
milk eggs and peanuts mainly
self reported food allergy is 6x higher than proven allergy and
6% in child, 1-2% in adult
What is the difference between non-immune mediated and immune mediated adverse food reactions?
Immune mediated are allergies and are IGE or non IGE mediated
How long does IGE mediated symptoms take to onset?
5-30mins
What food may cause an IGE mediated response?
Milk, eggs, peanuts, fish, fruit and veg
What is the presenting age for IGE mediated response?
Variable as at age of contact
When would symptom onset start for non IGE mediated allergy?
Delayed- hours to days
What are common foods that cause non IGE mediated?
Milk, soya, wheat, rice and oats
What is presenting age of non IGE?
Infancy and early childhood
Which is more likely to resolve IGE or non-iGE?
Non IGE
both can resolve but non IGE quicker
What is the difference between IGE and non-IGE presentation?
IGE is multisystem
non- IGE is eczema and gastrointestinal system
What is Urticaria/angioedema?
Acute (rarely chronic) hives and swelling with gastro- intestinal but not respiratory or CVS symptoms
What is food associated exercise induced anaphylaxis?
Food triggers anaphylaxis only if ingestion is followed temporally (within 2 hours) by exercise.
What is pollen food syndrome?
Pruritus and mild oedema confined to the oral cavity (lips, tongue, mouth and throat) uncommonly progressing. Associated with hay fever
What is protocolitis?
Passage of bright red blood in mucousy stools in otherwise asymptomatic infants
What is enterocolitis?
Multiple and varying gastrointestinal symptoms including feed refusal, persistent vomiting, abdominal cramps, loose and frequent stools and constipation
What is Eosinophilic oesophagitis?
Symptoms from oesophageal inflammation and scarring of feeding disorders reflux symptoms, vomiting, dysphagia and food impaction
What is food protein induced enterocolitis syndrome?
Primary affects infants. profuse vomiting leaing to pallor, lethargy and possibly shock
25% diarrhoea
What are the most common food allergies in infancy?
milk
egg
peanut
What are the most common foods allergies in early childhood?
Soya
wheat
trees nuts
fish, shellfish, kiwi, sesame
What is the most common allergy in adolesence?
fresh fruit and vegetables
What may make a food be less allergic?
If high temperatures or change in food matrix e.g. baked milk, baked egg, boiled peanut, tuna and salmon canned
What 4 things would you do to evaluate a child with possible food allergy?
Medical history,
Physical examination,
screening test, diagnosis verification
What would you find out in a medical history with a child with possible food allergy?
Context of reaction, symptoms and food considerations
How would you physically examine a child with possible food allergy?
Indentify manifestations, differential diagosis, other allergic conditions
What screening tests would you do to a child with possible food allergy?
Skin prick test and blood specific IGE
and an elimination die
What would you do as diagnosis verification for a child with possible food allergy?
Controlled oral food challenges
If you are allergic to one thing are you likely to be allergic to something similar?
yes e.g. cow and goats milk
What is the typical immunoassay for detection of specific IGE in 3 steps?
- Allergen is adsorbed and immobilised
to a solid phase. 2. Patient’s serum is added followed by
incubation for 30-60 minutes
followed by several washing steps. 3. Allergen-bound IgE is detected by an
enzymatically labeled anti-human IgE
monoclonal antibody.
What are you looking at in an IGE test?
ige circulating in blood
What are you looking at in a skin prick test?
Response of skin mast cells to allergens
Does IGE circulating correlate with severity of reaction?
no
How are food allergies managed?
Anticipatory allergy testing. dietetic advice for exclusions, emergency medication if needed, early introductions to food in infancy, desensitisation to food allergens, oral food challenges for diagnostic verification
If you do a skin test, what size would show a 95% chance of food allergy?
8mm
