Slovak, Andrej Jan Michal; (1996) Laboratory animal allergy. Doctoral thesis (M.D), UCL (University College London).

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Abstract

Work with laboratory animals is associated with a range of allergic disorders including rhinitis, conjunctivitis, skin whealing, asthma and anaphyllaxis. These disorders were investigated in an exposed population of 147 workers in a cross-sectional study which was part-repeated as a follow-up 6-7 years later. Workers sensitised to animal allergens but remaining in exposure were studied in a cooperative survey involving several institutions to assess the effect of respiratory protective equipment (RPE) and additional barrier precautions. The sensitivity, specificity and predictive value of atopy as a marker of proneness to laboratory animal allergy was explored together with the constancy and reliability of different concepts of atopy. A series of experiments to optimise animal room ventilation in relation to antigen suppression were performed and the limitations of this approach were considered. The diagnosis of early and difficult cases of occupational asthma was explored in a short series of case histories. Laboratory animal allergy was shown to be a common disorder (30%) separable on functional and immunological grounds into two predominant types rhinitis/conjunctivitis (20%) and asthma (10%). Asthma was strongly associated with positive specific skin prick tests and atopy. However atopy was not sufficiently good a predictive discriminant (35%) for it to be recommended as a screening procedure for employment exclusion. RPE provided protection which was incomplete for sensitised workers and assessment of this data using two different analytical conventions produced different results. An optimal animal room arrangement was characterised for steady-state ventilation but this was easily and seriously disrupted by operator entry and activity. Histamine challenge before and after work week exposure was more sensitive to early airways lability than FEV₁ and REFR measurements. In challenge studies FEF₇₅₋₈₅ was similarly more sensitive than FEV₁ and PEFR. These techniques showed promise for early and difficult diagnosis. Atopy defined by subjective criteria, past personal and family history, was found to be inconstant with a 40% shift in population definition in 6-7 years.

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