Working with male rodents may increase risk of allergy to laboratory animals

Background: Our aim was to study the risk of laboratory animal allergy (LAA ) among research staff working in laboratories separate from the animal con finement area. The roles of atopy and exposure intensity in LAA were studie d with special regard to exposure to male rodents, who excrete higher level s of urinary allergens than female rodents. Methods: Eighty rodent-exposed subjects gave blood samples for the analysis of total IgE, Phadiatop, and specific IgE against rat (RUA) and mouse urin ary allergens (MUA), and answered questionnaires. Air samples were collecte d for RUA and MUA aeroallergen measurement in both laboratories and animal confinement facilities. Results: Twenty percent of the subjects had IgE >0.35 kU/l to RUA and/or MU A, and 32% had experienced animal work-related symptoms, although 90% of ae roallergen samples from the research,department laboratories were below the detection limit (<0.26 ng RUA per m(3) and <0.8 ng MUA per m(3)). Atopy (p ositive Phadiatop), total IgE > 100 kU/l, other allergies (especially to ot her animals), or more than 4 years of exposure significantly increased labo ratory animal sensitization and symptoms. Working with mainly male rodents gave odds ratios (95% CI) of 3.8 (0.97-15) for sensitization and 4.4 (1.4-1 4) for symptoms. Subjects with both exposure to mainly male rodents and ato py or elevated total IgE had a 10-fold higher frequency of sensitization th an exposed subjects with neither risk factor. Conclusions: A majority of subjects with a combination of exposure to mainl y male rodents and atopy or elevated total IgE developed sensitization to a nd symptoms from laboratory animals. Current low exposure seems to maintain the presence of specific IgE. Further measures must be undertaken to provi de a safe workplace for laboratory animal workers.