Children's Allergies - top tips from Dr George Du Toit
Dr George Du Toit, Consultant Paediatric Allergist at Guy's & St Thomas’ NHS Trust, holds outpatient clinics at The Portland and leads our pioneering Allergy Challenge Service; this service is also led by Professor Gideon Lack. Dr Du Toit is a popular speaker at our GP educational events; here Dr Du Toit offers some allergy tips:
1. Early onset eczema is a significant risk factor for development of food allergy:
There are now many studies that show a significant association between eczema and food allergies in childhood. The associations are strongest for eczema that is of a moderate to severe severity and of earlier onset i.e. before four months of age. The onset of sensitisation to food allergens occurs in early childhood and commonly in children with eczema and therefore eczema in early childhood should be seen as the harbinger of allergic woes to come, known as the Atopic March. It is very important therefore that early-onset eczema is treated as best possible in an attempt to reduce sensitisation to food and aero-allergens as this frequently occurs through the skin.
2. Early onset egg allergy is a significant risk factor for development of peanut allergy:
As for eczema there are many studies that demonstrate that egg allergy, which is one of the commonest food allergies, is a significant risk factor for the development peanut allergy. Indeed, at least 25% of egg allergic children in the UK will go on to develop peanut allergy. Where one allergy is suspected in the family, particularly egg, and even milk allergy, testing should be performed for other food allergens in order that safe dietary expansion and indeed restriction can be advised for the family.
3. 60% of peanut allergic children will become allergic to other nuts:
Mono food allergy has become increasingly rare and most children will now present with more than just a single allergy. There are patterns of co-reactivity between allergens such as between peanuts (a legume/pulse) and tree nuts and/or sesame; indeed, 25% of peanut allergic children will become allergic to sesame. This knowledge justifies expansive allergy testing in children who present with a single nut and/or seed allergy as this will not only prevent further reactions but also allow for safe dietary expansion.
4. Diagnostic allergy testing can be performed in young infants:
There is a misconception that allergy testing cannot be performed in younger children. Recent data demonstrates that up to 3% of infants at a year of age are peanut allergic (this was demonstrated in Australia but the rates are likely to be similar in the UK), this represents a significant disease burden at such an early stage of life among unselected children. Recent knowledge demonstrates very clearly that allergic sensitisation for many children will develop in the first few months of life and often before known exposure to the allergen. For example, 90% of peanut reactions occur with first known exposure with most reactions occurring in the first year or two of life. The implications are therefore that in the high risk setting (strong family history, early-onset eczema, milk or egg allergy suspected) and when early complementary solid feeding has commenced beyond traditional safe weaning foods (e.g. root vegetables, baby rice, fruit, oat) then it is prudent to perform diagnostic allergy testing (Skin Prick Test and/or Specific-IgE ).
5. The gold standard investigation for the diagnosis of allergy to antibiotics is a supervised oral provocation test:
Around 10-20% of the general population are labelled as being penicillin allergic. This suspicion commonly arises due to a rash that developed at the time of illness in early childhood. Many illnesses in children are associated with rashes and so it is easy for confusion to arise and for a label of penicillin allergy to be diagnosed. Diagnostic testing to antibiotics using skin prick testing and IgE’s is generally of little help and we therefore now commonly proceed (after performing a thorough allergy history) with a supervised oral drug challenge. The majority of the antibiotic challenges we undertake have negative outcomes which allows for the removal of the ‘allergic label’ from the patients records. This is an important diagnostic process as there are infections for which Beta-Lactam antibiotics remain the drug of choice and this class of antibiotics have beneficial safety and therapeutic characteristics that are not always shared by alternate antibiotic classes.