Sensitization to horse allergens in Italy: a multicentre study in urban atopic subjects without occupational exposure.

Background: Horses play a significant role in people's leisure time in Italy and other countries, but few data are available on IgE-mediated sensitization to horse allergens in patients without occupational exposure. We assessed, in a multicentric survey, the prevalence of horse sensitization in atopic subjects and its clinical characteristics.

Methods: Allergists from the whole Italian territory were required to collect the results of skin prick tests from at least 100 consecutive subjects. Those patients with a positive skin test to horse dander underwent a detailed interview concerning clinical history, pet ownership and possible exposure.

Results: Data from 3,235 outpatients were collected and 2,097 had at least 1 skin positivity. Among them, 113 (5.38%) were sensitized to horse dander (9 monosensitized). Thirty patients reported direct horse contact (4 owners and 26 for riding or occasional contact), 23 patients were sometimes in contact with horse owners and 60 subjects denied any direct or indirect exposure. Among 9 horse monosensitized patients, 6 had intermittent and mild rhinitis and 3 persistent moderate/severe rhinitis plus asthma. Three of them were horse owners or riders and the remaining had no contact with the animal.

Conclusions: Our data evidence that the rate of sensitization to horse dander is not negligible and probably underestimated. In susceptible, not occupationally exposed individuals, horse contact, but also indirect or no apparent exposure, may induce sensitization. We recommend inclusion of horse allergen in the routine panel for the diagnosis of respiratory allergy.