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

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

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

Hygiene Hypothesis ‘Why is allergy becoming more common?’

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

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

Types of allergic conditions Asthma Hayfever Eczema Food allergy

Food allergy

IgE mediated allergy (‘immediate’ ie peanut allergy)

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

IgE mediated allergy Diagnosis

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

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

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?

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

IgE mediated allergy Management

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’

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

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

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.

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

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

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

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.

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

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

Questions