Childhood allergies and childhood allergy medicine

1. Childhood allergies and childhood allergy medicine Dr Tom Blyth Paediatric ConsultantMaidstone and Tunbridge Wells NHS Trust

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

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 allergyManagement

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 • 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