Session 2 - Lecture 1 - Food Allergy

Question 1

1 - Title

Answer 1

Food allergy:
Assessment and diagnosis

Dr David Luyt
Consultant Paediatrician
Leicester Children’s Allergy Service

“paediatric consultants at LRI – the reason why we’ve put this together is bc it’s a big area, if you work with children OR adults, you will have a lot of exposure to allergy if you work in primary care. So we thought it prudent to have a session with a general focus on allergy”

Question 2

2 - Synopsis

Answer 2

Synopsis
Learning objectives

• What is allergy?
  • Why is allergy important?
  • Key words and definitions.
  • How does allergy present?

- Food allergy:
• What is food allergy?
• How does food allergy present?
• How do we diagnose food allergy?
• How do we manage different food allergies? 

“1c. cover presentations (briefly) as we can’t cover the entire topic.
2. Chosen food allergy as we can’t cover all allergies – put together theme and cases, will be the theme of the afternoon – these are sort of common presentations that we might get from primary care. Most of that are referrals, even though we are a sort of secondary, tertiary service, come from GP colleagues, so if you are going to be in GP, going to see a lot of this – and what we want to look at is how we diagnose allergy”

Question 3

3 - Learning objectives

Answer 3

Synopsis
Learning objectives

• What is allergy?
  • Why is allergy important?
  • Key words and definitions.
  • How does allergy present?

- Food allergy:
• What is food allergy?
• How does food allergy present?
• How do we diagnose food allergy?
• How do we manage different food allergies?

Question 4

4 - Why is allergy important?

Answer 4

Why is allergy important?

• Allergy is COMMON:
  • ALLERGIC RHINITIS (AR) affects up to 30% of adults.
  • ASTHMA is diagnosed in >1 IN 10 UK schoolchildren.
  • FOOD ALLERGY is confirmed in about 6% of children.
  • Nearly half of UK adults suffer from at least one allergy.
• Allergy is associated with SIGNIFICANT MORBIDITY:
  • Persistent symptoms of AR impair sleep and REDUCE PRODUCTIVITY.
  • Recurrent hospital admissions for asthma cause HIGH ABSENTEEISM.
  • Restrictive diets in food allergy cause SOCIAL EXCLUSION and malnutrition.
• Allergy can be FATAL
  • Around 1200 people die from asthma in the UK each year.
  • Admissions for anaphylaxis increased >600% in the 20 years to 2012.

www.AllergyUK.org

“So why is it important? Well it’s common – about a 1/3 of people have AR. Asthma is diagnosed in >1 in 10 people in the UK at sometime in their lives and food allergy is CONFIRMED in about 6% - you’ll see that it’s suspected in a much higher proportion of children and adults. Nearly half of UK adults suffer from at least one allergy. There is a significant morbidity with allergy – will talk about AR this afternoon but a lot of evidence to say it impairs sleep and reduces productivity e.g. poorer school grades, causes recurrent hospital admissions for asthma causing high absenteeism. It can be fatal, food allergy not so common but asthma is – you can see statistics,, year or 2 old but probably still relevant, anaphylaxis admissions declining – not mirrored by increase in mortality despite diagnosis.”

Question 5

5 - What is allergy?

Answer 5

What is allergy?
Key words and definitions

ALLERGY:
• Is NOT A DISEASE itself, but a MECHANISM leading to disease.
• Originally defined in 1906 as “specifically altered reactivity of the organism”.
• Now defined as:
• “IMMUNOLOGICAL HYPERSENSITIVITY that can lead to a
• variety of DIFFERENT DISEASES via different PATHOMECHANISMS
• with different approaches in DIAGNOSIS, THERAPY and PREVENTION”.

Ring J. What is allergy? Global atlas of allergy (2014)

“1. Well this is a working diagnosis, but not a disease itself – but a mechanism leading to disease

2. something that has been around for more than 100 years – well known.
3. Here’s some sort of conditions:
   3a. Immunological mechanism – repeated immunological mechanism: immunological hypersensitivity
   3b. variety of different diseases with a variety of different mechanisms and
   3c. obvs diff approach to diagnosis, prevention and therapy.”

Question 6

6 - Define frequently used terms in allergy (1)

Answer 6

What is allergy?
Key words and definitions

Definitions of terms frequently used in allergy

• ALLERGEN: Any substance stimulating the production of IgE or a CELLULAR IMMUNE RESPONSE. Usually a PROTEIN, but can be carbohydrates (much less common).
• SENSITIVITY: NORMAL response to a stimulus.
• HYPERSENSITIVITY: ABNORMALLY STRONG response to a stimulus.
• SENSITISATION: Production of IgE antibodies (detected by serum IgE assay or SPT) after repeated exposure to an allergen.
• ALLERGY: A hypersensitivity reaction initiated by specific IMMUNOLOGICAL mechanisms. This can be IgE mediated (e.g. peanut allergy) or non-IgE mediated (e.g. milk allergy).

Muraro A et al. Food Allergy and Anaphylaxis Guidelines. Allergy (2014)
Boyle R. Allergy Illustrated textbook of Paediatrics (2017)

“So what’s an allergen? Any substance that stimulates the production of IgE (can also talk about non-IgE mediated food allergy) or a cellular immune response (not conclusively added) Usually a protein (most cases), but can be a carbohydrate, but this is much less common. Sensitive – normal stimulus response; hypersensitivity – abnormally strong response. Sensitisation – individuals start developing an immune response to repeated allergen exposure, an allergy is when all of these come together – so hypersensitive reaction mediated by specific immunological mechanism – see as we talk this morning about IgE mediated and non IgE – v important concept in food allergy.”

Question 7

7 Define frequently used terms in allergy (2)

Answer 7

What is allergy?
Key words and definitions

Definitions of terms frequently used in allergy

• ATOPY: A tendency to PRODUCE IgE ANTIBODIES in response to ordinary exposure to potential allergens. Strongly associated with asthma, rhinitis, eczema and food allergy.
• ANAPHYLAXIS: A SERIOUS allergic reaction with bronchial, laryngeal and cardiovascular involvement that is RAPID in onset and can cause DEATH.
• 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.
• FOOD ALLERGY: IMMUNOLOGICALLY mediated adverse reaction to food.

Muraro A et al. Food Allergy and Anaphylaxis Guidelines. Allergy (2014)
Boyle R. Allergy Illustrated textbook of Paediatrics (2017)

“1. perhaps a slightly dated term – talk about an atopic individual – one who has a potential for allergy, strongly associated with clinical conditions.
2. worst diagnosis – clearly, if you need to involve CV/resp system needs to be involved for that to occur”

Question 8

8 - How does allergy present?

Answer 8

How does allergy present?
Major allergic diseases
- Allergic rhinitis (Hay fever): Blocked/runny nose, itchy nose, sneezing. Triggered by pollen, pets or HDM.
- Allergic conjunctivitis: Red, swollen, itchy, watery eyes. Can occur with allergic rhinitis.
- Asthma: Chest symptoms of wheeze, cough, shortness of breath and tight chest. Not always allergic.
- Atopic dermatitis Eczema: Commonest chronic inflammatory skin disease with itch and excoriation
- Urticaria (Hives): Acute/chronic (±6w) maculo-papular pruritic rash without or with angioedema
- Insect allergy: Mainly to bee or wasp stings. Mild (local), Moderate (urticaria) Severe (anaphylaxis)
- Drug allergy: Especially to antibiotics, but only a minority who are labeled /drug allergic/ are truly allergic.
- Food allergy: Clinically broad symptom spectrum varying in timing of presentation and in severity.

“So, how does allergy present? Well I think you probably know – don’t need to be a doctor to know these – v common conditions, common in English languages. Hayfever – recognise characteristic symptoms and triggers – inc pollen or house dust mites, true allergic raction. Conjunctiitis often goes with AR, with similar triggers. Asthma – today is not about asthma, in fact actually it is a small part of my work in an allergy clinic altho quite a few of my pts will have a bg of asthma. Association with allergy is tenuous though, so allergen removal mechanisms or immunological manipulation mechanisms don’t fare v well in controlling asthma. Eczema is also the condition tht doesn’t sit very well with allergy and v often is not associated; not caused by allergy but see common in individuals who are allergic. Urticaria (hives) – manifestation of certainly acute allergic reactions that can occur on its own – and in that instance can be either acute or chronic, acute period lasting < or chronic > than 6 wks respectively. Insect allergy e.g. wasp sting allergy, anaphylaxis, much more common in adults than in children. Drug allergy – often presumed when individuals given an antibiotic to an illness (probably viral) then associated with a rash – then allergy is presumed - minority labelled are TRULY allergic. And last is food allergy, and we will speak more about that this afternoon.”

Question 9

9 - How does allergy present?

Answer 9

How does allergy present?
Major allergic diseases

[pictures which correspond to diseases on Slide 8]

• Allergic rhinitis (Hay fever)
• Allergic conjunctivitis
• Asthma
• Atopic dermatitis (Eczema)
• Urticaria (Hives)
• Insect allergy
• Drug allergy
• Food allergy

Question 10

10 - How does allergy present?

Graph

Answer 10

How does allergy present?
Graph
EDIT

“Important to us to think about Presentation of allergy in children – useful study, a demi study which illustrates that. Change in prevalence according to disease, Eczema rhinoconjunctivitis, etc. eczema is much more prevalent in infancy and then reduced in prevalence as you get older – food allergy is the same, about 6% of children allergic to food but only about 2% of adults. Most of these allergies disappear with age. Asthma peaks around 10-15 age, allergic rhinitis is a late developing station becomes the predominant allergic condition.”

Question 11

11 - How does allergy present? The Allergic March

Answer 11

How does allergy present?
The Allergic March

• Rhinitis
• Asthma
• Eczema
• Food Allergy

“And so we’ve got this what we call the allergic march – which is a sort of graphical presentation of what we just showed - age on x-axis, prevalence on y-axis.”

Question 12

12 - How does allergy present?

Answer 12

How does allergy present?
Changes in prevalence of sensitisation with age

[GRAPH EDIT]

Nissen SP et al. The natural course of sensitization and allergic diseases from childhood to adulthood (2013)

“And parallel to that, is also sensitisation, and individuals that become sensitised, quite sensitised before these clinical manifestations appear, so food sesnitisations apartment sensitisation in pre-school children then as you get older, pollen dust mite become important in AR, and These therefore mirror clinical presentations. “

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