Insect-sting hypersensitivity — branching viva

Opening. Take me through how you recognise and manage this child in the first five minutes. [2]

Recognition. This is systemic anaphylaxis to a wasp sting — multisystem within minutes, with skin (flushing, lip and tongue swelling), respiratory (wheeze, distress) and early cardiovascular (dizziness) involvement. Up to a fifth of systemic sting reactions have no skin signs, so I would not wait for a rash. [2]

Immediate management. Call for help, remove any retained stinger by scraping sideways, lie him flat with legs raised because he is dizzy, give high-flow oxygen, and give intramuscular adrenaline into the anterolateral thigh — 300 micrograms, as he is around ten years and roughly 30 to 50 kilograms. Repeat every five minutes if no response, give an intravenous crystalloid bolus of 10 mL/kg for shock, and add an inhaled bronchodilator for refractory wheeze. [1] [2]

Branch — refractory. If he needs two or more adrenaline doses or remains shocked, escalate to an intravenous adrenaline infusion titrated to response. If he is on a beta-blocker and refractory to adrenaline, give glucagon. Manage refractory disease with senior or PICU support. [2]

Investigation. Anaphylaxis is clinical — treatment never waits for a test. I would arrange timed serum tryptase on arrival, at one to two hours, and at baseline at least twenty-four hours later. A normal acute tryptase never excludes venom anaphylaxis. [5]

Branch — tryptase and severity. Why does the baseline tryptase matter? Because the Ruëff data showed it is the strongest predictor of how severe the next sting will be, and an elevated value screens for clonal mast-cell disease (KIT D816V) — the severe-reactor phenotype. [5] [9]

Workup. At four to six weeks in the allergy clinic I would confirm the culprit with venom-specific immunoglobulin E and skin testing, measure the baseline tryptase, and use component-resolved diagnostics (Ves v 5 for genuine yellowjacket) if he tests positive to several insects. [1] [3]

Definitive prevention. Because he had a systemic reaction, I would refer him for venom immunotherapy with the vespid extract. The Cochrane review confirms it substantially reduces systemic reactions to subsequent stings, and once maintenance is reached it gives around 90 to 98 per cent protection over three to five years of treatment. [4] [3]

Discharge package. Before he leaves I would prescribe an adrenaline autoinjector by weight band, a written action plan, medical identification, and educate the family and school on avoidance (footwear, not flailing at insects) and device use. The autoinjector rescues the next reaction; venom immunotherapy prevents it. [2] [4]

Examiner's closer. Name the culprits and the regional twist. Honeybee leaves the embedded sac, vespids (yellowjacket and wasp) sting repeatedly and are the commonest temperate culprits, and the ants carry regional importance — the jack-jumper in south-eastern Australia, the fire ant in the southern United States. [1]