Allergy and Allergic Diseases

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Allergy and Allergic Diseases

• Incidence steadily rising
• Trebling in the last 20 years
• 1/ /3 of the population will develop clinical
  allergic condition
• Amongst the highest rates in the World
• Costs Quality of Life issues
• 3 million consultations costing 300 million
  70,000 Admissions costing 80 million 1
  billion drugs expenditure

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Allergic Diseases adverse, heightened
immunological responses (hypersensitivity) to
external agents
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Allergic disease prevalence

• Asthma
• X 6 in Children
• X 3-4 in Adults
• Population Prevalence 12 15

Atopic Dermatitis Allergic Rhinitis Food
Allergy also increasing Anaphylaxis 7-fold
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Asthma / Allergic Disease Genetics

• Strong Genetic Association
• Cytokine genes IL-4, IL-5, IL-10, TGF-b
• IgE receptor genes
• LPS responsiveness genes
• Skin barrier function genes - fillagrin
• Twin Concordance 75
• 1 affected parent - 40
• 2 Affected Parents - 60
• Same Disease - Even Higher

but genes do not explain the growing prevalence
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Asthma Epidemiology
Socioeconomic factors

• West Germany Vs East Germany
• Prevalence Studies
• Inverse relationship with
• Family Size
• Family Order
• Day Care in Early Years Outside the Home
• Place of residence Farm / Animal exposure Vs
  City

Asthma Prevalence Vs GNP per capita adapted from
ISAAC study
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The Hygiene Hypothesis
Centers for Disease Control, Atlanta
Promotion of Allergic Immune Responses
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The Infant Immune System
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The Infant Immune System Normal Maturation
Controlled Inflammation
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Allergy Investigation

• HISTORY
• Laboratory tests (RASTs) / in-vivo skin testing
  IgE-dependent
• Challenges Useful Experienced Monitored
  setting
• Usefulness Disease / Interpreter
• Alternative testing no basis in logic

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Allergy Management
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Allergy Management cont./
Immune Manipulation

• Conventional Immunosuppression
• Variable
• Not Widespread

• Allergen Desensitization Therapy / Immunotherapy
• Molecular engineering
• Allergen sequencing
• IgG4 / TGF-b production

• TH Redirection
• M. Vaccae
• Probiotic therapies
• Allergen / Cytokine / CpG motif Conjugate
  Vaccines

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Allergy Management cont. 2/
Anti-IgE Therapy
Stopping the Cascade

• Humanised Mouse MAb
• Omalizumab
• Asthma
• Reduced steroid use hospitalization rescue
  treatments
• Reduced IgE IgE Receptor
• FDA Approval 2003
• Incorporation in Asthma Guidelines

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ANAPHYLAXIS
/ - Stridor Breathing / Speaking Difficulty
Hypotension Collapse GI Symptoms
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Epidemiology

• Sharp increase
• Under-reported
• 30 950 / 100,000 / year US meta-analysis
• 0.5 2.0 lifetime prevalence
• 1 / 12 / year recur
• UK 75 / 100,000 / year
• Fatalities 1 / 2.5 million / year lower in
  children

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Triggers

• Potentially anything careful history
• Commonest -
• Foods peanuts Other tree nuts fish and
  shellfish milk
• Venoms wasp, bee
• Drugs penicillins anaesthetics ASA and
  NSAIDs ACEIs
• Other Medical Contrast media Latex

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Why Does This Happen?
Foods peanut egg milk seafoods Drugs penicillin
s suxamethonium Mabs Latex Venoms
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Adrenaline Autoinjectors

• UK Resuscitation Council Guidelines
• Irish Consensus Document from IGI IMJ Jan 2008
• Definite
• Anaphylaxis in Asthma
• Limited access to care
• Trace amount triggers
• Severe hypotension ( venoms)
• Probably
• High incidence of Severe reactions ( nuts /
  shellfish)
• Comorbidities
• No
• Asthma alone positive skin tests alone clear
  avoidable trigger positive family history

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Food Sensitivity and Other Allergic Disorders

• Does Food Allergy Cause Other Conditions?

• Atopic Eczema
• Co-existence of conditions
• High Frequency of RAST / PST Positivity
• Severe gt Mild Younger gt Older
• Exclusions
• Challenges

• Asthma
• Severe acute reactions
• Early food allergy positively predicts later
  asthma
• Younger gt Older
• Consider in difficult asthma

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Asthma / Allergy Prevention

• Food allergen avoidance / Breastfeeding
• - food allergy prevention
• Other allergic disorders ?
• Exposure to allergens in infancy e.g. house dust
  mite food antigens pollens --? IgE production
• Early food exposure as a preventative in at risk
  infants?
• Conflicting evidence re pet exposure
• RESEARCH

Early Allergen Exposure