Abstract

Background
Historical data suggest 15% of laboratory animal workers develop IgE sensitisation and 10% symptoms of laboratory animal allergy (LAA), including occupational asthma. Individually ventilated cages (IVCs) are replacing conventional open cages; we sought to evaluate their impact on the development of LAA.

Methods
We surveyed 750 laboratory animal workers and measured airborne Mus m 1 (mouse allergen) levels in seven UK institutions. We compared the prevalence of sensitisation to mouse proteins (by specific IgE assay or skin prick test) and of work-related allergic symptoms in IVC-only and open cage units.

Results
Full-shift Mus m 1 levels were lower in IVC than open cage units (geometric mean 1.00 (95% CI 0.73–1.36) versus 8.35 (95% CI 6.97–9.95) ng·m-3; p<0.001), but varied eight-fold across the IVC units (geometric mean range 0.33–4.12 ng·m-3). Primary analyses on data from 216 participants with =3 years exposure to mice revealed a lower prevalence of sensitisation in those working in IVC units compared with conventional cage units (2.4% (n=2) versus 9.8% (n=13); p=0.052). Sensitisation in IVC units varied from 0% to 12.5%; the use of fitted respiratory protection was less common in IVC units where prevalence of sensitisation was higher. Work-related allergy symptoms were more frequently reported by mouse-sensitised individuals (46.7% versus 10.9%; p<0.001) and only by those working in open cage units.

Conclusion
In contemporary practice, LAA is now largely preventable with the use of IVC systems and the judicious use of appropriate respiratory protection.

Full Text

Comments

This cross-sectional study of laboratory animal workers handing mice showed that allergen levels in the air and sensitisation was less in units where the mice were kept in individual ventilated cages (with HEPA filters on top), and less in units where fitted respiratory protection was used.

7/4/2019