A 69-year-old woman was fit and well until one August when she was stung on the back of her right hand by a wasp. She had previously been stung on several occasions, the last time 2 weeks earlier. Within 5min, she felt faint, followed shortly by a pounding sensation in her head and tightness of her chest. She collapsed and lost consciousness and, according to her husband, became grey and made gasping sounds. After 2-3min, she regained awareness but lost consciousness immediately when her husband and a friend tried to help her to her feet. Fortunately, a doctor neighbour arrived in time to prevent her being propped up in a chair: he laid her flat, administered intramuscular epinephrine (adrenaline) and intravenous antihistamines and ordered an ambulance. She had recovered fully by the next day.
Her total serum IgE was 147iu/ml (N < 120iu/ml). Her antigen-specific IgE antibody level to wasp venom was 21U/ml (RAST class 4) but that to bee venom was 0.3U/ml (RAST class 0). The patient was a candidate for specific allergen injection immunotherapy (hyposensitization) for her wasp venom anaphylaxis. The slight but definite risk of desensitization was explained and balanced against the major risk of anaphylaxis should she be stung again. The first injection consisted of 0.1ml of 0.0001µg/ml of wasp venom vaccine given subcutaneously. No reaction occurred, but local reactions are common. Over the next 12 weeks, gradually increasing doses were given without adverse effects. Over this period, she tolerated injections of 100µg venom. She then continued on a maintenance regimen of 100µg of venom per month for 3 years.