1. Childhood allergies and childhood allergy medicine
Dr Tom Blyth
Paediatric Consultant Maidstone and Tunbridge Wells NHS Trust
Eugene Weinburg – head of asthma and allergy clinic at the Red Cross Hospital in Johnasburg – sebatical at St Mary’s

2. Subjects covered Terminology Reasons for allergy
Types of allergic conditions
Food allergy
IgE-mediated ‘immediate’
Non-IgE mediated ‘delayed’
Prevention
Eczema and food allergy
Summary and questions

3. Terminology Various terms eg Hypersensitivity Allergy Intolerance
To avoid confusion, just describe the actual symptoms

4. Hygiene Hypothesis
‘Why is allergy becoming more common?’

5. Hygiene Hypothesis Developed world Developing world Family size
Exposure to parasites
Infections
Antibiotic exposure
Farming exposure
Small
Low
Few
High
Large
Many
Microbiological exposures
Allergy and autoimmune disease
No allergy or autoimmune disease

6. Gut tolerance induction
Microbiological exposures tolerise the gut immune system.
These immune cells migrate to systemic lymph system, leading to systemic tolerance
Main effect is early in life
Can sometimes induce specific tolerance by later allergen exposure

7. Types of allergic conditions
Asthma
Hayfever
Eczema
Food allergy

8. Food allergy

9. IgE mediated allergy (‘immediate’ ie peanut allergy)

10. IgE mediated food allergy:
affects upto 6% of infants <3 years
affects upto 2-4% of all children
in the UK is predominantly due to: milk, egg in infancy and nuts (esp peanut), fish in older children
Usually outgrow allergy to milk and egg by school age
Approx ¼ will outgrow peanut allergy

11. IgE mediated allergy Diagnosis

12. Clinical history
IgE mediated food allergy should have the following features:
Acute onset of symptoms (itchy nettle rash, swelling, asthma, stomach pain/ vomiting/ faintness/ collapse)
Occurring immediately/ soon after ingestion of food
on more than one occasion
on every exposure
recently

13. Clinical history
If a child can eat a portion of the food without problem, then he/she is not allergic
I ask if they can eat: peanuts, other nuts, milk, egg, fish, bread, peas/beans, fruits, sesame
Sometimes families don’t realise their child is allergic

14. Allergy tests Specific IgE blood tests ‘RAST tests’ Skin prick tests
Food challenge – the only definite test
Others
Do you need to allergy testing at all?

15. Skin prick testing and specific IgE
Can’t do a blanket screen – have to look for individual allergens.
No relation between test result and severity of allergy
Test result relates to the likelihood of being clinically allergic
Cannot interpret test result without the history

16. IgE mediated allergy Management

17. Dietary issues Nuts Not usually allergic to all nuts
Common patterns – single allergy to peanut, allergy to cashew and pistacchio
Need to discuss which nuts the child should avoid, both at home and when at school/ restaurants etc
Need to discuss what to do about ‘may contain traces’

18. Dietary issues Nuts (cont)
Not usually allergic to pine nut (be careful of pesto sauce)
Coconut allergy not associated
No current treatments available
Clark et al 2014 (Cambridge) showed desensitisation to peanut may work. Not currently in clinical practice.
Review every 2-3 years

19. Dietary issues Milk and Egg Fish
Discuss introducing baked milk/ baked egg(eg milk in biscuits, egg in cake) to induce tolerance
Gradually increase milk/ egg content using milk/ egg ladders
Likely to outgrow allergy to whole milk/ cooked egg by 3-4 years of age (often sooner)
Fish
Only food that aerosolises
Usually allergic to all fish except tuna

20. Management plans
I usually recommend Adrenaline autoinjectors to food allergic children with
Asthma OR
Previous cardiorespiratory reaction
My view is that avoidance advice is more important than whether to prescribe Epipen or not.

21. Follow-up Ensure asthma is well controlled
Ensure family are successfully avoiding allergic reactions
Advise regarding whether allergies have been outgrown
Check Adrenaline autoinjectors
Inform about any new treatments

22. Non-IgE mediated (delayed) allergy
Variety of clinical features
Eczema, infantile colic, GORD, diarrhoea, blood in stools, constipation, tiredness etc
No tests
Diagnosis based on exclusion (2-6 weeks) and reintroduction
Assess nutritional implications of exclusion

23. Prevention of allergy
Recent studies (LEAP/ EAT studies) introduced peanuts (and other foods) early.
Results show reduced allergy in those infants given foods early.
UK advice currently is to introduce allergenic foods from 6 months
No benefit from delaying introduction
If high risk of allergy – aim to breastfeed

24. Eczema and food allergy
Consider food allergy in:
– children who have reacted immediately to a food
– infants and young children with moderate or severe uncontrolled atopic eczema, particularly with gut problems or failure to thrive.

25. What do I do in allergy clinic?
Use targeted allergy history to identify possible allergies
Confirm suspected allergies with allergy testing
Advise on what to do to manage the confirmed allergies, and when/how to reintroduce foods
Try to give reassurance

26. Take home messages Allergies are common
They are manageable, without major impact on a child’s daily life
Allergy tests are not definitive
There is a general move towards safe tolerance induction, rather than strict avoidance.
Many allergies do outgrow

27. Questions