1. Allergy and anaphylaxis

2. • Definitions
• Basic immunology of allergy
• Testing for specific IgE
• Food allergy
• Insect allergy
• Drug allergy
• Anaphylaxis
• Management of anaphylaxis

3. Definitions (EAACI/WAO)
• Hypersensitivity is objective reproducible symptoms
or signs, initiated by exposure to a defined stimulus
that is tolerated by normal subjects
• Allergy is immune mediated hypersensitivity
• Allergens are antigens, usually proteins, that cause
allergy
• Atopy is a personal and/or familial tendency to
become sensitised (ie. produce IgE) in response to
normal exposure to allergens, with development of
asthma, rhinoconjunctivitis and eczema

4. • Anaphylaxis is a severe potentially life-threatening
systemic allergic reaction characterised by rapid
onset of life-threatening airway breathing of
circulatory problems, and is usually but not always
associated with skin or mucosal changes

5. Allergy Nomenclature
Hypersensitivity
Allergic hypersensitivity
(immunological mechanism
defined or strongly suspected)
Non-allergic hypersensitivity
(immunological mechanism
excluded)
IgE-mediated Non IgE-mediated

6. IgE

7. Mast cells

8. Sensitisation
1.1

9. Sensitisation
1.2

10. Allergy = allergen specific IgE and symptoms upon
exposure to allergen
1.4

11. Ref: ASCIA 20101.7
Signs and symptoms of allergy and anaphylaxis
Some individuals experience anaphylaxis without prior mild or
moderate symptoms

12. Testing for Specific IgE
• Skin prick testing
• Intradermal testing
• Serum fluoroenzymeimmunoassay (AKA
ImmunoCap, “RAST”)
• Basophil activation assays (whole blood)

13. Detection of specific IgE in serum
Principle
• Allergen in solid phase
• Patient serum containing
specific IgE
• Detection
ALLERGEN
Detection Ab
IgE

14. Skin Prick Testing

15. t = 1 minute

16. t = 4 min

17. t = 8 min

18. t = 10 min

19. t = 15 min
Rye grass 8mm
Bermuda grass 7mm
Johnson grass 9mm
Bahia grass 9mm
Ragweed 6mm
D. pteronyssinus 10mm
D. farinae 8mm
Cat dander 6mm
Dog dander 5mm
Mould mix 4mm
Positive control 6mm
Negative control

20. Serum tryptase
Ref: Simons, Camargo. 2010; Yunginger, Squillace et al. 1989; Sampson, Menderson et al. 1992.
• Serum tryptase should be measured within 4 hours after anaphylaxis
• Serum tryptase is often normal after food anaphylaxis
3.9

21. Food allergy can be IgE mediated
and/or non-IgE mediated

22. IgE mediated food allergy
• Acute urticaria/angioedema
• Contact urticaria
• Anaphylaxis
• Immediate gastrointestinal hypersensitivity
• Food-dependent exercise induced anaphylaxis
• Oral allergy syndrome (food-pollen allergy
syndrome)

23. Food allergy or food intolerance?
Food intolerance:
• does not involve the immune system
• does not result in IgE mediated reactions including anaphylaxis
• symptoms can sometimes resemble those of mild or moderate
food allergy
There is no reliable skin or blood test to diagnose food intolerances
Diagnosis of food allergy and risk of anaphylaxis should always be
medically confirmed
1.2

24. Food allergy
Whilst 90% of food allergic reactions are caused by allergic reactions to
these foods, any food can cause an allergic reaction
1.11

25. Food allergy is common
2.3
In Australia:
• Children < 1yr: 10%
• Children < 5 yrs: 4-8%
• Adults: up to 2%

26. Natural history of food allergy
• Peanut, tree nut, fish, sesame and shellfish allergies
usually persist
• Milk, egg, soy and wheat allergy commonly resolve
• 85% of young children in population based studies
outgrow their allergy to milk or egg by age 3-5 years
2.4ref: http://foodallergens.ifr.ac.uk Skripak, JACI 2007, Savage, JACI 2007.

27. Cause of Allergic ReactionPercent
Peanut 60% 0.190968 37
Tree nut 27% 0.087742 17
Fish 2% 0.005161 1
Milk 8% 0.025806 5
Shrimp 3% 2
62
0% 10% 20% 30% 40% 50% 60% 70%
Peanut
Tree nut
Fish
Milk
Shrimp
Percent of Cases
Cause of Fatal Anaphylaxis
Common causes of fatal food anaphylaxis
Ref: Pumphrey, Garland. 2007 2.8
Shrimp (prawn)

28. AATHP 28 August 2011
• Majority of food-allergic individuals need to eat >500 mg
• Significant minority reacts to lower amounts
*Lowest Observed Adverse Effect Levels (LOEALs)
• Touching or smelling the allergen may cause mild/moderate
reaction but unlikely to cause anaphylaxis
Ref: Pumphrey. 2004, http://foodallergens.ifr.ac.uk, VITAL, 2007. 2.9
Small amounts of food can trigger anaphylaxis in
some very sensitive individuals

29. Oral allergy syndrome
1.3
Aero-
allergen
Homologous
food allergen
• Mild oral
symptoms
• ≈ 7%
anaphylaxis

30. Oral allergy syndrome

31. • Occurs in response to physical exertion
• Symptoms only occur if exercise within few hours of eating
specific food/s
• Most common foods:
– Wheat, other grains and nuts in Western populations
– Wheat and shellfish in Asian populations
– Fruits, vegetables, seeds, legumes, various meats, cow’s milk
and egg
• Symptoms include extreme fatigue, warmth, flushing, pruritus
and urticaria progressing to anaphylaxis
• Diagnosis usually based on clinical history
• Avoid culprit food/s for at least 4-6 hours before exercise
Food dependent exercise induced anaphylaxis
1.11

32. Insect stings are a common trigger of
anaphylaxis
7.1
Common triggers:
• Honey Bees (most common)
• Paper wasps
• European Wasps (becoming more common)
• Australian Jack Jumper Ant stings

33. 7.2
Bites less commonly trigger anaphylaxis than
insect stings
Although bites are common in endemic areas, anaphylaxis
is rarely triggered by:
• Ticks
• Mosquitoes
• March Flies

34. Reactions
• Typical local reactions:
– Erythema and painful swelling (up to 5cm) that
develops within minutes and resolves within hours
• Large local reactions
– 10%
– 10cm
– Peak at 48 hours and resolve over 5 – 10 days
– Risk of systemic reactions 5 – 15%
– May be IgE mediated
• Anaphylaxis

35. • Systemic toxic reactions
– Dose dependent
• Unusual reactions
– Toxic or non-IgE immune mediated
– Serum sickness like syndromes
– Hypersensitivity vasculitis

36. • Anyone with insect venom
anaphylaxis should be referred to a
clinical immunology/allergy
specialist, even if no immunotherapy
to allergen currently exists
• Adrenaline autoinjector should be
prescribed for all patients with
anaphylaxis to insect venom;
consider alert bracelet
When to refer for immunotherapy – insect venom
allergy
36

37. Drug allergy allergy
Adverse reactions to drugs is a significant problem, however allergic reactions (IgE
mediated) are rare:
• Antibiotics
– Uncommon
– Testing is only available for a limited range of antibiotics
• General anaesthetics
– Rare
– Specialised testing required
• Local anaesthetics
– Rare
– Vasovagal reactions are common
• Vaccination
– Rare, occurs in approximately 1/250,000 doses
• NSAIDS
– The majority of reactions are not IgE mediated
– IgE mediated reactions to NSAID are characterised by urticaria, angioedema or
anaphylaxis
1.13Ref: Up-to-date, 2010

38. Anaphylaxis
• Anaphylaxis is a severe potentially life-
threatening systemic allergic reaction
characterised by rapid onset of life-
threatening airway breathing of circulatory
problems, and is usually but not always
associated with skin or mucosal changes

39. Triggers of anaphylaxis
Common
• Foods
• Insects
• Medications
Uncommon
• Latex
• Exercise (with or without food)
• Cold temperature
• Immunisation (rare)
• Unidentified (idiopathic)
1.6

40. 112 anaphylaxis deaths in Australia between
1997 and 2005

41. Anaphylaxis deaths by
cause and age group

42. Fatal anaphylaxis - associations
• Asthma
• Delayed or no administration of adrenaline
• Age:
– Teenagers and young adults (food allergy)
– Adults (insect and drug allergy)
• Upright posture during anaphylaxis
• Food allergic individuals eating away from home
• Initial misdiagnosis
• Systemic mastocytosis
Previous mild/moderate reactions may not rule out subsequent
severe or fatal reactions
Ref: Bock. 2010; Liew, Williamson, Tang. 2008; Bock. 2007; Pumphrey. 2003; Bock. 2001
2.7

43. Signs of anaphylaxis
• Difficult/noisy breathing
• Swelling of the tongue
• Swelling or tightness in throat
• Difficulty talking and/or hoarse voice
• Wheeze or persistent cough
• Persistent dizziness or collapse
• Pale and floppy (young children)
Mild or moderate signs and symptoms may not
always precede anaphylaxis

44. All individuals at risk of anaphylaxis should:
• Know what to do in an emergency
• Have an ASCIA Action Plan for Anaphylaxis completed by their
medical practitioner
• Carry an adrenaline autoinjector and know how to use it
Management of anaphylaxis anaphylaxis
1.5

45. Why is adrenaline effective?
• Inhibits the release of inflammatory mediators
• Reverses the physiological effect of mediators by:
– Reducing airway mucosal oedema
– Inducing bronchodilatation
– Inducing vasoconstriction (thus increasing HR & BP)
– Increasing strength of cardiac contraction
Lasts ~ 15-20 minutes; repeated doses may be needed
after 5 minutes if no response
Ref: Tole, Lieberman. 20074.4

46. There are two brands of adrenaline autoinjectors –
EpiPen® and Anapen®
• Junior devices (150µg) recommended for
children 10 to 20 kg (aged ~1-5 years)
• Higher dose devices (300µg) recommended for
children over 20 kg (aged over ~5 years) and
adults
EpiPen Jr Anapen Jr
Anapen
5.2
EpiPen

47. Orange needle end
Blue safety
release
Viewing window
EpiPen with orange needle end and blue safety release
Expiry date
Instructions on
how to use
(on other side)
5.5
• Available in Australia mid 2011

48. How to give EpiPen with orange needle end and blue safety
release
5.6

49. Patient’s
photo and
personal
details
Confirmed
allergens
Contact details
for family and
doctor
Adrenaline
autoinjector
brand name
Signs, symptoms,
action for mild or
moderate
allergic reactions
Instructions
on how to
use the
device
Signs, symptoms,
action for
anaphylaxis
Additional
information
6.3

50. PBS supply of adrenaline autoinjectors in Australia
• Maximum of 2 (EpiPen or Anapen) for both children and adults
• Initial supply:
– When risk and clinical need has been assessed by, or in
consultation with a clinical immunologist, allergist,
paediatrician or respiratory physician
– After hospital or emergency department discharge for acute
allergic anaphylaxis treated by adrenaline
• Continuing supply for anticipated emergency treatment of acute
allergic reactions with anaphylaxis, where the patient has
previously been issued with an authority prescription for this
drug
5.14

51. Guidelines for prescribing an adrenaline autoinjector
Always recommended if…
•History of anaphylaxis (and continued risk)
•These patients should be referred to a clinical immunology/allergy
specialist
May be recommended if…
•History of a generalised allergic reaction and one or more risk
factors:
– Asthma
– Age (children >5 yrs, adolescents, young adults)
– Specific allergic triggers
– Co-morbidity (e.g. ischaemic heart disease)
– Geographical remoteness from emergency medical care
•These patients should be referred to a clinical immunology/allergy
specialist
5.15

52. Guidelines for prescribing an adrenaline autoinjector
Not normally recommended...
• Asthma with no history of anaphylaxis nor generalised allergic
reactions
• Positive allergy test without a history of clinical reactions
• Family history of anaphylaxis or allergy
• Bee stings
− local reactions only (children and adults)
− generalised rash only (children)
• These patients generally do not need referral to a clinical
immunology/allergy specialist
5.16