Studies of the natural history of stinging-insect allergy: long-term follow-up of patients without immunotherapy.

This study reports the clinical and immunologic responses of 29 patients who were observed during a prolonged period after insect-sting anaphylaxis without venom immunotherapy. At the time of their initial evaluation, all patients had venom-specific IgE, detected by skin test or RAST. Their mean age was 21 years; 16 patients were 16 years of age or less. There were 18 male and 11 female patients. Eleven patients had urticaria and angioedema as their only symptoms of anaphylaxis, and 18 patients had respiratory and/or cardiovascular symptoms. Reassessment was done 5 or more years after the initial evaluation. The average time at reevaluation was 10.1 years after the initial sting reaction. There had been 25 re-stings in 17 patients, with three systemic reactions occurring in two patients, an overall reaction rate of 12%. The time interval between the initial sting reaction and the follow-up sting was 2 to 14 years, mean 7.3 years. In patients with initial urticaria/angioedema symptoms only, there were 11 re-stings with no reactions. In patients with initial cardiovascular/respiratory symptoms, there were 14 re-stings with three reactions. At the time of follow-up evaluation, venom-specific IgE had generally decreased. In six of 25 patients, venom skin tests became negative, and in eight of 24 patients, the RAST became negative. These observations suggest that in many patients, stinging insect allergy is a self-limited process, with loss of clinical sensitivity and immunologic reactivity.