Home environment exposure assessment in hypersensitivity pneumonitis

Abstract

Objective: To identify the causal agent in hypersensitivity pneumonitis.

Method: Between 2015 and 2020 an occupational hygienist performed an exposure assessment in the home environment of patients with hypersensitivity pneumonitis (HP), in whom common causes of HP were excluded. If indicated, work place exposure was assessed. Indoor and outdoor air samples were analysed for fungi. In the case of qualitative or quantitative abnormal patterns in the analysed samples indicating the presence of an etiologic agent, serology (double diffusion/Ouchterlony and electrosyneresis on cellulose acetate) was performed for general panels and specific fungi.

Results: Assessment was performed in 41 patients (23-73 yrs). In 8 (20%) a source and causal agent was identified in the home environment, in two cases results were controversial. Main sources were carpets, mouldy bathrooms, poorly maintained dwellings and a car air conditioning. Among causal agents were Aspergillus spp., Penicillium sp., Wallemia sebi, Botrytis cinerea, Trichoderma pseudokoningii, Cephalotrichum sp., Thermoactinomyces vulgaris and goose feathers. Additional exposure assessment in the work place was performed in 8 patients, which revealed a causal agent in another 3 cases and one controversial finding. Sampling repeated in 2 cases after removal of the source showed that the causal agent was no longer present.

Conclusion: A causal agent was identified in at least 25% of patients with HP. Standard protocols for indoor air sampling and individual tailored serology may contribute to the diagnosis of HP and intervention (Reboux G, et al. Indoor Air 2019; 29:5-16).

This study is part of ZonMw project Topzorg, PRJ140088