Objective: To investigate the prevalence of and factors associated with the presence of α-gal–specific IgE in a risk group of foresters and forest workers from La Rioja, Spain and in a control group.
Methods: The study population comprised 169 workers and 100 individuals who did not recall having had tick bites. A questionnaire including demographic data and number of tick bites per year was completed by a physician. α-Gal sIgE was assessed using ImmunoCAP with serum samples that had been taken in 2010. In 2015, second serum specimens were taken from all but 1 of the workers, who had positive specific IgE to α-gal in 2010. These new samples were tested for IgE to the α-gal epitope and to mammalian meat.
Results: The prevalence of positive sIgE to α-gal was 15% in the risk population and 4% in the control population. α-Gal sIgE positivity was associated with the number of tick bites per year and with seniority. Thirteen out of 21 patients sensitized to α-gal in 2010 showed positive specific IgE to α-gal in serum samples from 2015. Eleven had specific IgE to mammalian meat, but none reported symptoms of meat allergy.
Conclusion: The prevalence of α-gal sIgE antibodies in this risk population was higher than in the control group and was associated with the number of tick bites per year and with seniority. None of the workers sensitized to mammalian meat developed meat allergy, possibly owing to the low levels of sIgE to α-gal.

Key words: Allergens and epitopes, IgE, Anaphylaxis, Tick bites, α-Gal