1. Allergy in a ‘nutshell’ GP guide to survival
Dr Gillian Vance

2. Starts with early diagnosis
Allergy care
Starts with early diagnosis

3. Session
Better understanding of the basic immunological mechanisms underlying food allergic disease
Apply mechanisms to clinical evaluation & appropriate therapy

4. Objectives Recognise typical features of allergic disease
Appreciate areas of complexity
Explain what, how & why we evaluate at the allergy clinic

5. ‘Allergy’
1st coined in 1906 by Austrian paediatrician, Clemens von Pirquet
‘altered reactivity’ to any antigenic stimulation, whether
Immunity – protection
Hypersensitivity – adverse clinical response

6. ‘Allergy’
‘An exaggerated sensitivity to a substance (allergen) that is inhaled, swallowed or injected, or that comes into contact with the skin or eyes’

7. Allergic disease spectrum
Food allergy
Eczema
Asthma
Allergic rhinitis
Drug allergy

8. Allergy – a public health problem
Prevalence of asthma & hayfever have increased over the last 20 years ( % and % respectively) Upton, BMJ 2000
12 million people per year may seek treatment for allergy
Children: 20.4% asthma; 18.2% hayfever; 47% 1 or more current symptoms (ISAAC study, 1999)

9. Epidemiology of Food Allergy
Peanut allergy (3 yr olds)
Sensitisation: threefold increase from %
Doubling of reactivity from 0.5-1% JACI 2001;107:S231
Admission rates
Anaphylaxis risen 7-fold; 5/million 1990/ /4
Food allergy risen 7-fold; /million
Urticaria doubled; 20 – 44/million – especially children
Figures more impressive for food allergy.
Rpt birth cohort survey of 3-4 year olds on IOW:
Impact of FA on healthcare usage:

10. Allergy – a primary care problem
6% of GP consultations
Primary Care Prescribing
: community prescriptions increased
Nasal allergy - by 60% (to 4.5 million)
Anaphylaxis – 12 fold (to 124,000)
Ocular allergy – by 50% (to 1.4 million)
Costs NHS £900 million pa
Excludes costs of A&E attendances, outpatient consultations, hospital treatment
BSACI, London, commissioned study, 2002

11. Why should children with suspected allergy be tested?
May be lifelong
Specific treatment
Early treatment may influence severity
May be life threatening
Associated with poor quality of life
May herald other allergic diseases
‘Allergic March’

12. Eczema
Asthma

13. Adverse Reactions to Food
Adverse Reaction to Food
Toxic
Food poisoning
Non toxic
Aversion
Non-immune mediated
Enzymatic
Pharmacological
Undefined
Immune mediated
Allergy
IgE
Non IgE

14. Non-immune ARF ‘Undefined’ Mechanism unknown
Food additives, preservatives, colourings
‘Generally Recognised as Safe products [GRAS]
Sulphites, nitrites, nitrates, MSG
Urticaria, rhinitis, asthma, migraine

15. Food Allergy - Definition
An immune-mediated adverse reaction to food that occurs in genetically predisposed individuals
IgE urticaria; oral allergy; anaphylaxis
Non IgE Cell-mediated; mixed
Consistent
Reproducible

16. How does the immune system malfunction in food allergies
How does the immune system malfunction in food allergies? Step 1: Sensitisation
IgE production
B cell
Th2-biased cytokine production
Th cell
Allergen Exposure
Processing
Presentation

17. Step 2: Activation - Effector Phase
Vasodilatation
Pain
Cell recruitment
Mucosal oedema
Immune Modulation
IgE induction
Tissue remodelling
Smooth muscle contraction
Peristalsis

18. Clinical Manifestations: Immediate
Erythema
Pruritus (generalised)
Urticaria
Angioedema
Rhinitis
Laryngeal oedema
Asthma
GI upset

19. Symptoms Immediate Delayed type / Chronic Inflammation Abdominal pain
Altered gut function
Poor asthma control

20. Clinical Manifestations: non IgE-mediated reactions
Delayed type
SKIN: eczema flares
GUT:
Mucousy / bloody stools in an infant
Chronic diarrhoea, vomiting
Failure to thrive
Malabsorption
Dysphagia, abdominal pain
Proctitis / dietary protein enteropathy / eosinophilic gastroenteropathies

21. What foods?
Cow’s milk, Egg white, Soybean, Wheat, Peanut, Tree nuts, Fish & Shellfish account for >90% reactions

22. Red flag features of allergy
Clear temporal relationship with trigger
Consistency of reaction
Trigger – likely allergen
Timing – within 2 hours of ingestion
‘Typical’ clinical symptoms
Other features of atopy
Family history of atopy

23. Example 1 3½ year old girl Eczema since 1 year age
Ate 1 salted peanut 18 months ago
Developed
lip swelling & wheeze
No rash, GI upset or respiratory distress
Mum – asthma & hayfever

24. Example 2 11 year old girl No other atopic disease
Xmas - ate raisin from bowl of mixed nuts
Developed lip swelling & local urticaria 5 – 10 minutes later
Settled with oral piriton
Father – eczema & occasional ‘wheeze’

25. What’s the diagnosis?
Peanut allergy
Tree-nut allergy
‘Other’

26. Diagnostic Adjuncts Skin Prick Testing Specific IgE measurement Cheap
Painless
Fast
Sensitive & specific
Specific IgE measurement
Blood test
Hx of anaphylaxis
Recent antihistamine use
Widespread eczematous skin

28. Skin prick test

29. Results - cases Case 1: Case 2: SPT peanut 6 mm
SPT tree nut panel negative
Specific IgE peanut 5.6 kU/L
Case 2:
SPT brazil nut 4 mm; remainder negative
Specific IgE peanut 90 kU/L; brazil 2.4 kU/L

30. Interpretation Case 1: peanut allergic
Case 2: peanut & tree-nut allergic
SPT weal size or Specific IgE level
No relation with severity of reaction

31. Red flag features of management
Awareness
Avoidance
Asthma control
Anti-histamine
Adrenaline autoinjector

32. Management AWARENESS Parents Wider family School Physician
GETTING THE DIAGNOSIS RIGHT

33. Management
AVOIDANCE OF ALLERGENS

34. Management
AVOIDANCE

35. Management
ASTHMA CONTROL

36. Management
ANTI-HISTAMINE

37. Management
ADRENALINE (EPINEPHRINE)

38. Who should get an epipen?

39. ‘KISS OF DEATH FOR NUT ALLERGY GIRL’
Lethal anaphylaxis
Uncommon
0.65-2% of severe anaphylaxis
‘KISS OF DEATH FOR NUT ALLERGY GIRL’
A teenage girl with an extreme allergy has died after kissing her boyfriend who had eaten a peanut-butter sandwich hours earlier.
Christina Desforges, 15, from Saguenay, Canada, went into anaphylactic shock. She was given an adrenalin shot and taken to hospital but died four days later from acute respiratory failure.
Doctors said that a nut allergy brought on by the kiss was the cause of death. The boy, who has not been named, had minute traces of peanut on his lips.
Nov ‘05

40. Lethal anaphylaxis: ‘predictable’ risk factors
Peanut / treenuts
Asthma
Adolescents / young adults

41. Lethal anaphylaxis: ‘unpredictable’ risk factors
Severity history of previous food reaction
Pumphrey
22% of fatal cases had had previous severe reaction

42. Severity History
Macdougall et al, 2002, Arch Dis Child

43. Red flag features of epipen prescription
Indicated:
History of severe reaction
Reactions becoming more severe
Asthma (requiring inhaled steroid use)
Consider:
If low dose (trace) exposure
At a distance from nearest medical facility
If having difficulty avoiding
If parents anxious +

44. Prognosis

45. IgE mediated reactions
Resolve: Cow’s milk, Egg, Soya, Wheat
By 5 years age, tolerance in
85% of CMA children
66% of egg allergic children
Persist: Peanut, Tree nut, Fish & Shellfish
However, around 20% of PA will resolve
Youngest patients
Low specific IgE
Mild reaction at presentation

46. Frequently Asked Questions

47. Is a food allergy causing my child’s hyperactivity?
Number of ways in which food could affect cognition & behaviour in children
Mechanism not ‘allergy’
Some benefit in ‘extreme’ subgroups
Complex behavioural problems +/- neurological deficits
Possibility that food additives may have a pervasive effect across the population

48. ‘Food Allergy’ & behaviour
Bateman study
277 children
Hyperactivity / atopy
Randomised, placebo-control, Double blind, cross-over: food colouring & Na benzoate
Assessed weekly by psychologists; parents daily
Parental ratings associated with dietary additives
No association with atopy

49. ‘Food Allergy’ & behaviour
Confirmed in follow on study
3-year old children (n=153)
8/9 year old children (n=144)
Within subject crossover – 2 active mixes; 1 placebo (3 year olds x2 56g sweets; 8 yr olds 2-4 bags sweets / day
Global Hyperactivity Aggregate increased in both age groups with active mix

50. My child has egg allergy – should he have the MMR?
YES
Unless
Immunocompromised
Had an anaphylactic reaction to previous MMR
Had an anaphylactic reaction to gelatin / neomycin
Close observation if
Previous acute severe reaction to egg
Current active, chronic asthma

51. (Other) Indications for referral
GI symptoms:
vomiting, diarrhoea, colic, FTT
Atopic dermatitis:
severe, persistent, young child, allergen-related
Chronic urticaria:
duration > 6 weeks
Wheezers / asthmatics
Rhinitis / conjunctivitis
Severe, persistent, treatment-resistant, allergen-related
Insect allergy (not local reaction – even if large)

52. What have we learned? Allergy has a wide range of manifestations
Diagnosis relies on careful history taking, & appropriate interpretation of IgE testing.
Management represents a ‘package’ of education, specific allergen avoidance measures, relevant pharmacotherapy & possibly desensitisation (inhalants)
‘Early’ evaluation can make a difference to both the child & family life

53. Thank you for listening
Feel free to discuss / refer your patients to the allergy team.