Screening for indoor allergens in student's dwellings in Alentejo, Portugal

Abstract

Background: In “healthy” homes and buildings most of the fungi come from external sources and the total number of fungi is usually lower than in the outdoor environment. On the other hand, pollen detected in the indoor environment is usually dependent on the concentration of ambient air pollen. The contribution of indoor expo-sure to allergic disease is undetermined. The aim of this work was to detect the presence of fungi and pollen in indoor environments in dwellings in Évora, south of Portugal, by molecular methods. Method: Electrostatic dust fall collectors (EDC), developed in the scope of the COST ADOPT action CA-18226, were used for indoor sample collection and placed near the entrance door of the house, living room or bedroom, during the 3rd week of November 2022.The bioaerosols counting was executed using standard Hirst-typetraps and identified by optical microscopy, according to the stand-ard methodology (REA.com). Eighteen volunteers participated in this study by completing a questionnaire and placing the EDC in a specific location in the house. For Real-Time PCR fungal detection, the Internal Transcribed Spacer (ITS) region was considered, and for airborne pollen detection, the trnL gene was selected. Results: The results of the bioaerosol counts showed that the largest outdoor contribution is represented by fungi. PCR results showed an amplification curve and a respective melting peak in all the samples for the ITS gene, and 8 out of 18 were positive for the trnL gene in samples placed next to windows. Electrophoresis results showed 2bands, demonstrating the presence of, at least 2 different fungal species. The results demonstrated that regardless of the sampled location the presence of fungi was detected. For pollen species, only 1 band was observed. Total DNA concentration extracted from the EDCs were around 4 ng/μL. Nevertheless, the low amount was still able to detect several bioaerosols in the indoor environment that are more difficult to detect by the standard methods. Conclusion: The results have shown that it is possible to identify different biological particles, from different species, in the indoor environment, contributing to generate alert systems to the populations and, thus being useful in outbreak prevention.