Pattern of sensitization to honeybee venom in beekeepers: a 5-year prospective study.

Beekeepers are at increased risk for honeybee (Hb) venom allergy and they represent a unique population for Hymenoptera venom studies. The aim of this was to prospectively examine the pattern of Hb venom sensitization over a 5-year period in new beekeepers and define possible predisposing factors. Thirty-five beekeepers were tested every 6 months for 5 years with in vivo and in vitro methods to detect the possible development of sensitization to Hb and common wasp (Cw) venom. Inclusion criteria included the lack of previous beekeeping activity and absence of sensitization or reported reaction to Hymenoptera stings. Subjects with both in vivo and in vitro tests that were definitely positive or with one definitely positive and the other doubtful were considered sensitized. Ten of 35 new beekeepers (28.6%) and 3 of 36 controls (8.3%) developed sensitivity to Hb venom during the 5-year period. The risk ratio in incidence studies was calculated at 3.43 (SE of log risk ratio = 0.61; 95% CI of risk ratio = 1.03-11.42). All sensitized beekeepers were detected within the first 18 months of occupational exposure; 8 of 10 (80%) beekeepers were detected during the initial 12 months and the 2 remaining beekeepers were detected between 12 and 18 months. One of 35 (2.9%) beekeepers and 1 of 36 controls (2.8%) were sensitized to Cw venom. The number of stings per year and atopy had no effect on sensitization rate. Although predisposing factors to sensitization or anaphylaxis could not be identified, beekeepers developed sensitization to bee venom in <18 months.