Screeening the Microbiome of House Dust in the Alentejo Region

Abstract

Objective: In this study, in the context of project HERO (Impact of Artificial Habitats and Environmental contaminants on Chronic RespiratOry Diseases), we conduct a pilot study to determine the presence of Sars-Cov-2 in house dust collected in Alentejo Region Homes. Methods: Seven volunteers were recruited to participate in this study to providing house dust samples obtained by vacuum cleaning (in a total of 16 samples collected between June 2021 and May 2023). Sample were sorted and sieved, and the <63 µm fraction used for nucleic acid extraction and after processing, amplified by RT-qPCR using the ALS SARS-CoV-2 commercial kit. Results: 83.3% of the samples tested positive for the presence of SARS-CoV-2. In 42% of the houses with positive detection, the occupants reported to have been Covid free. One of the houses tested around a whole year always had amplifiable virus in all collected samples despite a single positive test for one of the occupants being reported. In two of the samples only after dilution (1:5) was it possible to detect the virus. Conclusions: Infectious agents can be used as surrogates of Environmental Contaminants (chemical and biological) with potential effects in Chronic Respiratory Diseases’ symptoms/ exacerbations. Furhermore, indoor dust can be used as a straightforward, suitable and effective matrix for viral surveillance, being able to detect asymptomatic infections and, potentially, be used in early detection of spreading infections (particularly important in the presence of vulnerable people). The fact that only after dilution was possible to attain some detections, attests to the presence of PCR inhibiting chemicals, more prevalent in areas influenced by rural practices. The small number of houses sampled limits these conclusions.