The safety and efficacy of immunotherapy with aluminum hydroxide-adsorbed venom extract of Vespula spp. An open, retrospective study.

BACKGROUND: specific immunotherapy for Hymenoptera Venom (VIT) is considered a life-saving treatment in insect sting allergy. A few studies with depot VIT have been published, but they are mainly focussed on patients sensitized to Apis.

METHODS: this retrospective study was designed to evaluate both efficacy and safety of depot VIT for Vespula. Thirty-six patients (age range 6-73 years) with a history of systemic reactions (grade III to IV according to Mueller) after a Vespula sting, and specific sera IgE RAST to Vespula at least class 2, were administered a depot preparation of venom reaching 50 microgram as monthly maintenance dose. After the first year the maintenance dose was administered every other month. Thirty-three patients were treated for a minimum of 5 years. Reactions to any new field sting of the relevant insect were recorded during the treatment and for 6 to 24 months after its interruption.

RESULTS: the treatment showed an excellent tolerance, with only a few local side effects. Thirteen patients (11 Grade IV according to Mueller before VIT) under treatment showed only local reactions after each field sting (18 field stings in total) by the relevant insect. Four patients (3 Grade IV according to Mueller before VIT) had a total of 6 field stings after the interruption of the 5-year treatment, with only local reactions.

CONCLUSIONS: according to our results, and in agreement with previous published studies, VIT for Vespula spp. with depot extracts has an excellent tolerance and is clinically effective.