Space-time analysis of COVID-19 cases and SARS-CoV-2 wastewater loading: A geodemographic perspective.

Severe acute respiratory syndrome - coronavirus 2 (SARS-CoV-2) continues to effect communities across the world. One way to combat these effects is to enhance our collective ability to remotely monitor community spread. Monitoring SARS-CoV-2 in wastewater is one approach that enables researchers to estimate the total number of infected people in a region; however, estimates are often made at the sewershed level which may mask the geographic nuance required for targeted interdiction efforts. In this work, we utilize an apportioning method to compare the spatial and temporal trends of daily case count with the temporal pattern of viral load in the wastewater at smaller units of analysis within Austin, TX. We find different lag-times between wastewater loading and case reports. Daily case reports for some locations follow the temporal trend of viral load more closely than others. These findings are then compared to socio-demographic characteristics across the study area.

Droplet distribution and airborne bacteria in an experimental shower unit.

Although human exposure to water aerosols is common in residential showers, the droplet distribution patterns generated in showers are not well understood nor is the bacteria released during shower operation. In this study, a two-phase flow Particle Tracking Velocimetry (PTV) algorithm was successfully used to characterize the spatial spray pattern and velocity field in two experimental showers (one low-flow and one high-flow). In addition, the airborne bacteria present in the shower over nearly 5 months of controlled operation was determined for both showers. The results indicate that the droplet velocity out of the low-flow showerhead (which had fewer orifices) was significantly higher than that out of the high-flow showerhead resulting in a higher aerosol number concentration in the low-flow shower and more consistent wetting of the shower wall. Both showerheads generated droplets in the respirable range and genera of potential health concern were observed in the shower aerosols measured both prior to and following shower operation. The study provides one of the first visualizations of droplet spray patterns in residential showers and provides insight into the airborne bacteria present in showers.

Characterizing the bacterial communities in retail stores in the United States.

The microorganisms present in retail environments have not been studied in detail despite the fact that these environments represent a potentially important location for exposure. In this study, HVAC filter dust samples in 13 US retail stores were collected and analyzed via pyrosequencing to characterize the indoor bacterial communities and to explore potential relationships between these communities and building and environmental parameters. Although retail stores contained a diverse bacterial community of 788 unique genera, over half of the nearly 118K sequences were attributed to the Proteobacteria phylum. Streptophyta, Bacillus, Corynebacterium, Pseudomonas, and Acinetobacter were the most prevalent genera detected. The recovered indoor airborne microbial community was statistically associated with both human oral and skin microbiota, indicating occupants are important contributors, despite a relatively low occupant density per unit volume in retail stores. Bacteria generally associated with outdoor environments were present in the indoor communities with no obvious association with air exchange rate, even when considering relative abundance. No significant association was observed between the indoor bacterial community recovered and store location, store type, or season. However, predictive functional gene profiling showed significant associations between the indoor community and season. The microbiome recovered from multiple samples collected months apart from the same building varied significantly indicating that caution is warranted when trying to characterize the bacterial community with a single sampling event.