A Randomised, Double-Blind Pilot Study of Enzyme-Potentiated Desensitisation for Prophylaxis of Large Local Reactions to Mosquito Bites

Abstract

Primary Objective. To test the hypothesis that two injections of enzyme-potentiated mosquito antigen significantly reduce the size of experimental mosquito bites in participants with LLR-MB. Design. Randomised, double-blind, placebo-controlled, parallel group comparison over 3 months. Setting. Hospital outpatient clinic. Participants. Fifty adult participants of both sexes. Interventions. Two injections of mosquito antigen or matching placebo, 6 weeks apart. Main Outcome Measures. Early (1 hour) and late (24 hours) mean square root of erythema area (SREA) following controlled mosquito bite with the second bite given at least 6 weeks following the final injection. Results. At 1 hour, mean SREA was slightly higher in the EPD group compared to placebo after adjusting for baseline values (0.46, 95% CI −6.11 to 7.03), but this was not statistically significant (P = 0.89, ANCOVA analysis); neither were the results at 24 hours (−2.58, 95% CI −11.73 to 6.57) (P = 0.57). The proportion of participants experiencing a decrease in wheal size at 1 or 24 hours was similar between groups. Conclusions. EPD was not demonstrated to be effective for immediate or delayed LLR-MB. Methodological problems included a high variability in LLR-MB between subjects, suggesting that a crossover design should be used in future.

Insect hypersensitivity beyond bee and wasp venom allergy

“…Treating delayed cutaneous reactions with topical corticosteroids appears reasonable, but controlled studies do not exist. Immunotherapy trials have been carried out sporadically in the past and recently with mixed success [ 1 , 4 ].…”

EAACIposition paper: Comparing insect hypersensitivity induced by bite, sting, inhalation or ingestion in human beings and animals

“…Topical or systemic corticosteroids can be used to treat intense delayed reactions. Currently, no standardized allergen immunotherapy against biting insects is available; recent experimental approaches showed variable outcomes …”