Background: Exposure to laboratory animals often causes the appearance of immunologic sensitization and symptoms.
Objective: Our aim was to determine the incidence of occupational rhinoconjunctivitis and the timing of symptoms and their determinants in apprentices starting exposure to laboratory animals.
Methods: Data from 387 (92.8%) of 417 students entering career programs in animal health in 5 schools were kept for analysis. Questionnaires and skin prick tests with common and occupational inhalants were carried out on entry and at follow-up visits scheduled at 8, 20, 32, and 44 months, depending on the schools. Responsiveness to inhaled methacholine was assessed at entry.
Results: Ninety-three (24%) subjects showed incident occupational rhinoconjunctivitis symptoms, and 37 (9.6%) had symptoms combined with skin sensitization to an animal-derived allergen. Symptoms such as sneezing, rhinorrhea, and itchy eyes tended to develop early in the course of exposure. In two thirds of the subjects, symptoms persisted at subsequent visits. In a multivariate analysis the determinants of the appearance of rhinoconjunctivitis with or without allergic sensitization included sensitization to grass pollens (odds ratio [OR], 1.78; 95% CI, 0.99-3.19), as well as nasal (rhinorrhea in contact with dust: OR, 1.79; 95% CI, 1.05-3.05) and bronchial symptoms (chest tightness: OR, 3.31; 95% CI, 0.98-11.25; cough on exposure to strong odors: OR, 1.88; 95% CI, 0.98-3.59).
Conclusion: The incidence of occupational rhinoconjunctivitis symptoms with or without immunologic sensitization is high in apprentices starting exposure to laboratory animals. Symptoms related to histamine release are common in the early course of exposure. Determinants include immunologic and target-organ susceptibility.