Cutaneous reactivity to mosquito bites: effect of cetirizine and development of anti-mosquito antibodies

Abstract

Cutaneous reactivity to mosquito bites was examined in 27 adult volunteers exposed to Aedes communis mosquitoes. Twenty-three subjects showed a combination of immediate wealing and delayed bite-papules, two subjects each experienced only immediate or delayed cutaneous reactions and two were non-responsive to the bites. The mean size of wealing and the mean score of pruritus was similar in 19 non-atopic and in eight atopic volunteers. These results confirm that normal subjects exhibit different stages of sensitization to mosquito bites. At the onset of the mosquito season, immunoblotting showed that four of 21 subjects (19%) had IgG-class antibodies to a recently described 21.5 kD Aedes communis mosquito antigen. After a 10-day exposure to a mean of 47 mosquito bites, these antibodies were found in 10 subjects (48%) who exhibited both strong and weak cutaneous bite-lesions. A placebo-controlled, double-blind study with cetirizine 10 mg was performed to examine the effect of this non-sedating antihistamine on mosquito bites. The bite lesions were measured and pruritus scored at 15 min, 60 min, 12 hr, and 24 hr. Cetirizine decreased significantly immediate wealing and pruritus (P less than 0.01), but had no effect on the delayed symptoms. This result supports the view that immediate mosquito-bite reactions are histamine-mediated.