Venom Hypersensitivity

Transcription

1 Venm Hypersensitivity

2 Venm Allergy Large lcalised reactin ~ 10% in adults Systemic allergic reactins Up t 3% f adults Severe sting reactins in up t 1% f children In Australia, apprximately 2 fatalities per year Mst ccur between years, male US: > 50 cases per year

3 Fig 1. Causes f anaphylaxis deaths. There were 112 deaths between 1997 and 2005 in Australia. Causes are shwn. Liew et al. Anaphylaxis fatalities and admissins in Australia, JACI 123(2) 2009;

4 Aetilgy 3 families f hymenptera Bees (hneybees, bumblebees) Vespids (yellw jackets, hrnets, Eurpean/German wasps, cmmn wasp, paper wasp) Stinging ants (bull ant, jack jumper ant) Venms cntain multiple prtein allergens Hneybee venm immunchemically distinct frm ther hymenptera Vespid venms have high degree f crss reactivity Paper wasps nt as clsely related (50% YJ allergic)

5 Clinical Features Nrmal: transient pain, itch & swelling Large lcal reactins Delayed & prlnged lcal inflammatin, IgE-dependent mechanisms Increases ver hurs, reslve 3-10 days Systemic Reactin Cutaneus (60% children vs 15% adults)/gi/respiratry/cvs Reprts f chrnic urticaria & cld urticaria ccurring after insect stings Unusual patterns: nephrpathy, neurlgic syndrmes, ITP & rhabdmylysis

6 Current sting Identify insect: presence f sting Time f nset f reactin Signs f anaphylaxis Previus stings Histry Number f stings Time curse and severity f previus reactins Histry f asthma Scial histry: Risk f future sting Lcatin, time t nearest hspital

7 Risk f systemic reactin Sensitisatin t venm ccurs in > 30% f adults after a sting 15-25% f adults have a psitive venm test (SPT/sIgE) Cmmnly transient with 12% becming negative every year Asymptmatic sensitisatin assciated with a 17% incidence f systemic reactin t a subsequent sting Once a systemic reactin ccurs, risk f future reactin much higher Future reactins usually fllw same symptm pattern with sme variatin in severity

8 Risk f systemic reactin

9 Investigatins Diagnstic testing indicated if high risk f future anaphylaxis (> 10%) where immuntherapy culd be cnsidered Testing family members is nt recmmended (frequent ccurrence f psitive venm tests in asymptmatic individuals)

10 Investigatins Measure serum tryptase (& baseline) Mastcytsis Skin testing Intradermal testing using venm prtein extracts Psitive 65-85% f patients with cnvincing histry Negative: lss f sensitivity after remte sting reactin Perid f anergy weeks after repeat in 1-6 mths Insect venm sige Less sensitive Sting challenge Cnsidered impractical & unethical If negative, still 15-20% chance f systemic reactin frm subsequent sting

11 Management Preventin Cver up: lng sleeves, pants & glves utdrs Bees usually act in self-defence: light-clured clthing, avid perfumes Wasps nest in lgs, walls & undergrund Attracted t fd & drink Dn t drink blindly frm cans when utdrs Remve nearby nests prfessinally Drive with windws up

12 Management Lcal Reactins Oral H1-antihistamines Cnsider ral crticsterids Ice pack/analgesia Anaphylaxis Epipen & anaphylaxis actin plan Optimise asthma cntrl Immuntherapy

13 Immuntherapy Histry f systemic reactin t sting & psitive diagnstic test Varius recmmended schedules Achieve 100mcg maintenance dse 4-weekly Sme patients stretched t 8-12 weekly

14 Immuntherapy VIT reduces risk f systemic allergic reactin t 5% (wasp) & 15% (bees) Venm IgE initially rises then declines steadily ver time Systemic symptms ccur in 10-15% f patients Majrity reactins are mild 1/3 require medical treatment

15 Relapse after immuntherapy When sting reactins ccur after stpping immuntherapy, mst mild and usually less severe than pre-treatment reactin Risk factr fr relapse (?indefinite treatment) Very severe (near-fatal) sting reactin Systemic reactin during therapy (sting r injectin) Hney bee allergy Less than 5 years f VIT Children with 3-5 years f VIT have very lw chance f systemic reactin, even years after stpping treatment

16 Summary Children wh have had anaphylaxis at 40% risk f future systemic allergic reactin Immuntherapy reduces the risk f systemic allergic reactin Risk f relapse

17 Eczema Irvine et al. N Engl J Med 2011; 365: Lee et al. Aust Prescr 1 Jan 1998; 21:9-11 Allergic rhinitis & Asthma References Larche et al. Nature Reviews Immunlgy Octber : Natinalasthma.rg.au Walls et al. Med J Aust 2005; 182 (1): Greiner et al. The Lancet 17 Dec (9809): Busquet et al. ARIA Allergy April 2008 (63) ASCIA: Ecnmic Impact f Allergies Reprt 2007 Urticaria Zuberbier et al. Allergy 69 (2014): Magerl et al. Allergy 71 (2016) Latex Allergy UptDate ASCIA resurces: allergy.rg.au Venm Allergy Glden. JACI March (3) Glden. Immunl Allergy Clin Nrth Am May; 27(2):261-vii