Allergy in a

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Allergy in a nutshellGP guide to survival

• Dr Gillian Vance

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Allergy care
Starts with early diagnosis
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Session

• Better understanding of the basic immunological
  mechanisms underlying food allergic disease
• Apply mechanisms to clinical evaluation
  appropriate therapy

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Objectives

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

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Allergy

• 1st coined in 1906 by Austrian paediatrician,
  Clemens von Pirquet
• altered reactivity to any antigenic
  stimulation, whether
• Immunity protection
• Hypersensitivity adverse clinical response

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Allergy

• An exaggerated sensitivity to a substance
  (allergen) that is inhaled, swallowed or
  injected, or that comes into contact with the
  skin or eyes

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Allergic disease spectrum

• Food allergy
• Eczema
• Asthma
• Allergic rhinitis
• Drug allergy

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Allergy a public health problem

• Prevalence of asthma hayfever have increased
  over the last 20 years (3 - 8.2 and 5.8 - 20
  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)

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Epidemiology of Food Allergy

• Peanut allergy (3 yr olds)
• Sensitisation threefold increase 1989-1994-6
  from 1.1-3.3.
• Doubling of reactivity from 0.5-1 JACI
  2001107S231
• Admission rates
• Anaphylaxis risen 7-fold 5/million 1990/1- 36
  2003/4
• Food allergy risen 7-fold 16 - 107/million
• Urticaria doubled 20 44/million especially
  children

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Allergy a primary care problem

• 6 of GP consultations
• Primary Care Prescribing
• 1991-2004 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 AE attendances, outpatient
  consultations, hospital treatment
• BSACI, London, commissioned study, 2002

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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

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Adverse Reactions to Food
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Non-immune ARF

• Undefined
• Mechanism unknown
• Food additives, preservatives, colourings
• Generally Recognised as Safe products GRAS
• Sulphites, nitrites, nitrates, MSG
• Urticaria, rhinitis, asthma, migraine

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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

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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
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Step 2 Activation - Effector Phase
Vasodilatation
Pain
Cell recruitment
Mucosal oedema
Immune Modulation IgE induction
Tissue remodelling
Smooth muscle contraction Peristalsis
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Clinical Manifestations Immediate

• Erythema
• Pruritus (generalised)
• Urticaria
• Angioedema
• Rhinitis
• Laryngeal oedema
• Asthma
• GI upset

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Symptoms

• Immediate
• Delayed type / Chronic
• Inflammation
• Abdominal pain
• Altered gut function
• Poor asthma control

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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

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What foods?
Cows milk, Egg white, Soybean, Wheat, Peanut,
Tree nuts, Fish Shellfish account for gt90
reactions
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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

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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

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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

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Whats the diagnosis?

• Peanut allergy
• Tree-nut allergy
• Other

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Diagnostic Adjuncts

• Skin Prick Testing
• Cheap
• Painless
• Fast
• Sensitive specific
• Specific IgE measurement
• Blood test
• Hx of anaphylaxis
• Recent antihistamine use
• Widespread eczematous skin

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Skin prick test
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Results - cases

• Case 1
• SPT peanut 6 mm
• SPT tree nut panel negative
• Specific IgE peanut 5.6 kU/L
• Case 2
• SPT peanut 6 mm
• SPT brazil nut 4 mm remainder negative
• Specific IgE peanut 90 kU/L brazil 2.4 kU/L

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Interpretation

• Case 1 peanut allergic
• Case 2 peanut tree-nut allergic
• SPT weal size or Specific IgE level
• No relation with severity of reaction

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Red flag features of management

• Awareness
• Avoidance
• Asthma control
• Anti-histamine
• Adrenaline autoinjector

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Management

• AWARENESS
• Parents
• Wider family
• School
• Physician
• GETTING THE DIAGNOSIS RIGHT

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Management

• AVOIDANCE OF ALLERGENS

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Management

• AVOIDANCE

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Management

• ASTHMA CONTROL

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Management

• ANTI-HISTAMINE

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Management

• ADRENALINE (EPINEPHRINE)

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Who should get an epipen?
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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
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Lethal anaphylaxis predictable risk factors

• Peanut / treenuts
• Asthma
• Adolescents / young adults

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Lethal anaphylaxis unpredictable risk factors

• Severity history of previous food reaction
• Pumphrey
• 22 of fatal cases had had previous severe
  reaction

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Severity History
Macdougall et al, 2002, Arch Dis Child
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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

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Prognosis
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IgE mediated reactions

• Resolve Cows 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

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Frequently Asked Questions
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Is a food allergy causing my childs
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

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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

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Food Allergy behaviour

• Confirmed in follow on study
• 3-year old children (n153)
• 8/9 year old children (n144)
• 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

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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

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(Other) Indications for referral

• GI symptoms
• vomiting, diarrhoea, colic, FTT
• Atopic dermatitis
• severe, persistent, young child, allergen-related
• Chronic urticaria
• duration gt 6 weeks
• Wheezers / asthmatics
• Rhinitis / conjunctivitis
• Severe, persistent, treatment-resistant,
  allergen-related
• Insect allergy (not local reaction even if
  large)

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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

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Thank you for listening

• Feel free to discuss / refer your patients to the
  allergy team.