BACKGROUND:
Large local reactions to insect stings cause significant
morbidity and impair quality of life. Venom immunotherapy
is not recommended because of a low risk for future systemic
reaction and unproven efficacy in preventing large local
reactions.
OBJECTIVE:
To determine the feasibility of performing a controlled
trial to examine the efficacy of venom immunotherapy in
reducing the size and duration of large local reactions.
METHODS:
Sting challenge in 41 patients with previous large local
reactions and positive venom skin tests caused large local
reactions 16 cm or larger in 34 patients, and 29 consented
to treatment. Venom immunotherapy was initiated in 19, and
10 were untreated controls. Sting challenge was repeated
after 7 to 11 weeks (control patients then beganvenom immunotherapy),
and annually for as long as 4 years.
RESULTS:
After 7 to 11 weeks of treatment, the size and duration
of large local reactions decreased 42% and 53%, respectively,
in treated patients and 18% in controls (P<.01 for both).
The response was similar after 1 year, and improved after
2 to 4 years to 60% and 70%, respectively.
CONCLUSIONS:
Venom immunotherapy significantly reduced the size and duration
of the large local reactions, and the efficacy improved
over a period of 2 to 4 years of treatment. Further studies
are needed to establish the safety and efficacy of venom
immunotherapy for large localreactions, the optimal duration
of treatment, and the mechanism for the differences in degree
and rate of clinical response compared with venom immunotherapy
in systemic reactors.