Hypersensitivity to Vespula and Polistes: can we tell the primary sensitization from the clinical history?

OBJECTIVE To study the relationship between the primary sensitization to wasp venoms and the geographical and seasonal circumstances of the anaphylaxis-induced sting. METHODS We performed a retrospective review of 115 patients (age 10-80) who suffered a systemic reaction to a wasp sting. Season and type of locality (urban or rural) at the moment of the sting were recorded. Serum specific IgE levels to venoms from Vespula and Polistes were measured, and a primary sensitization was determined to whichever genus of wasp for which the highest class of specific IgE was observed. The primary sensitization in relation to the type of locality and the season was assessed using the chi-square test. RESULTS Most reactions occurred in urban areas (67.8 %), and in the summer season (63.4 %). Most patients were sensitized to Vespula venom (94.8 %). Primary sensitization was to Vespula in 56.5 %, to Polistes in 10.4 %, and undetermined in 33 %. The distribution of geographical areas did not show significant differences in relation to primary sensitization (p > 0.05). Most patients with primary sensitization to Vespula suffered the anaphylaxis-induced sting after the spring season, with a statistically significant result (p < 0.05). CONCLUSION In our population, the probability of Vespula sting is higher than Polistes sting when the reaction occurs after spring. This finding can help us to identify the responsible vespid when the diagnostic tests do not provide an accurate result.