Serum sickness-like syndrome due to mosquito bite.

Local inflammatory reactions at the site of a mosquito bite are frequent. Immediate systemic reactions have occasionally been reported. The first case of a patient with relapsing episodes of a serum sickness-like syndrome following mosquito bites is reported herein. A 62-year-old patient came to the emergency room complaining of sudden malaise, chills, fever, headache, cervical lymph node enlargement, arthromyalgia, generalized purpura and leukopenia 6 h after a mosquito bite. He had experienced multiple similar episodes in the last 20 years, also following mosquito bites. Infectious and autoimmune diseases were ruled out. Serum IgE was 9,102 kU/l. Prick test of whole-body Culex pipiens extract was positive. Specific IgE to Aedes communis was 2.25 kU/l. SDS-PAGE immunoblotting of the patient's serum with whole-body C. pipiens extract revealed 43 and 17 kDa IgG-binding proteins and 22 and 17 kDa IgE-binding proteins, neither of which were found with control sera. Skin biopsy was consistent with leukocytoclastic vasculitis. The presence of both mosquito-specific IgE and IgG in the patient's serum suggest a possible cooperative immune response leading to clinical manifestations of serum sickness.