Natural history of sensitization, symptoms and occupational diseases in apprentices exposed to laboratory animals

Abstract

The natural history of the development of sensitization and disease due to high-molecular-weight allergens is not well characterized. This study describes the timecourse of the incidence of work-related symptoms, skin reactivity and occupational rhinoconjunctivitis (RC) and asthma (OA); and assesses the predictive value of skin testing and RC symptoms in apprentices exposed to laboratory animals, in a 3-4-yr programme.Four-hundred and seventeen apprentices at five institutions were assessed prospectively with questionnaire, skin-testing with animal-derived allergens, spirometry and airway responsiveness (n~373). Depending on the school, students were seen 8 (n~136), 20 (n~345), 32 (n~355) and 44 (n~98) months after starting the programme.At all visits, the incidence was greater for work-related RC symptoms followed in order by skin reactivity, occupational RC, and, almost equally, OA and work-related respiratory symptoms. The incidence-density figures were comparable for each followup period and for most indices up to 32 months after entry into the study and then tended to decrease. The positive predictive values (PPVs) of skin reactivity to workrelated allergens for the development of work-related RC and respiratory symptoms were 30% and 9.0%, respectively, while the PPVs of work-related RC for the development of OA was 11.4%.Sensitization, symptoms and diseases occur maximally in the first 2-3 yrs after starting exposure to laboratory animals. Laboratory animals are a common cause of occupational asthma (OA) due to high-molecular-weight allergens [1]. Rat urine is the major and most potent source of inhaled antigens [1]. Although several crosssectional studies have been carried out as summarized elsewhere [1], very few longitudinal studies have followed laboratory animal workers prospectively. Cullinan et al.[2] followed a cohort of 342 previously exposed laboratory animal workers on a 6-month basis over a 3.5-yr interval. They reported incidence rates of 7.3/100 person-yrs for eye/nose symptoms, 4.1/100 person-yrs for the development of skin reactivity to rat urinary allergens, 4.8/100 person-yrs for skin symptoms and 3.5/100 person-yrs for respiratory symptoms. A cohort of 769 apprentices starting exposure to high-molecular-weight antigens, including 417 in animal-health technology programmes has previously been described [3]. In this specific programme, it was shown that 85 of the 394 participants 921.5% of persons at risk developed skin reactivity to laboratory-animal-derived allergens over the follow-up period, corresponding to 7.9/100 person-yrs [4]. It was also found that the incidence of OA defined by the presence of skin reactivity to a programme-specific antigen and significant changes in bronchial responsiveness to methacholine was 2.7% (28/1043 person-yr) [5]. The purpose of this analysis, carried out in the 394 participants in the prospective study of laboratoryanimal workers, was to describe the time-course of incident cases of skin reactivity, work-related rhinoconjunctivitis (RC) and ...

Controversies in epidemiology of occupational asthma

“…Determinants for the development of specific sensitisation, symptoms and disease are different in atopic and nonatopic subjects [46]. The rate of sensitisation was higher in the first 2 yrs (out of a total of 4 yrs) of training (10.3 and 10.7% for years 1 and 2, respectively), as was work-related rhinoconjunctivitis (12.5 and 13.9% for years 1 and 2, respectively), whereas respiratory symptoms took longer to appear (maximum incidences of 3.2 and 2.5% in years 2 and 3 of the programme, respectively) [8]. The incidence of probable OA was 2.7% (28 out of 1,043 person-yrs).…”

“…Prospective cohort studies are more expensive than cross-sectional studies but are more powerful and less likely to be affected by selection or survivor biases; in particular, it is often possible to track the participants who leave the cohort and determine the possible effect of attrition on the estimates of both the frequency of OA and exposure/effect relationships [3]. This type of study has recently been successfully applied in cohorts of young apprentices [4][5][6][7][8][9][10]. Some case-referent studies have been carried out in the field of OA [11,12].…”

Occupational asthma caused by samba (Triplochiton scleroxylon) wood dust in a professional maker of wooden models of airplanes: A case study

“…Atopy increases the risk of development of occupational asthma due to sensitization to the high molecular weight allergens [22][23][24][25]. It was observed in bakers and farmers exposed to flowers and animals allergens [26][27][28]. There is no sufficiently proved relationship between atopy and occupational sensitization in the case of allergy to wood dust allergens, which are classified as the low molecular weight allergens.…”

Asma ocupacional

“…Destacan los realizados en trabajadores expuestos a enzimas 7 , sobre trabajadores de laboratorio, panaderos 8 en los que se detectó una incidencia acumulada de sensibilización a harina y alfaamilasa del 10,1% y de síntomas respiratorios en el 9%. Gautrín y col 9 estudiando trabajadores expuestos a animales de laboratorio encontraron que la tasa de sensibilización y la rinoconjuntivitis fue más alta en los 2 primeros años, si bien los síntomas respiratorios aparecieron sobre el tercer año. La incidencia de AO probable fue 2,7%.…”