Evaluating various composite sampling modes for detecting pathogenic SARS-CoV-2 virus in raw sewage

Area of Science:

• Environmental microbiology
• Public health surveillance
• Molecular epidemiology

Background:

• Inaccurate wastewater sampling can bias viral concentration estimates, impacting public health decisions.
• Sporadic viral input in wastewater necessitates robust sampling strategies for reliable monitoring.

Purpose of the Study:

• To determine the optimal composite sampling strategy for representative SARS-CoV-2 detection in raw wastewater.
• To evaluate different time intervals and windows for wastewater composite sampling.

Main Methods:

• Field trial in residence halls using composite samplers with 1h to 24h intervals and various time windows.
• Quantification of SARS-CoV-2 and pepper mild mottle virus (PMMoV) RNA using reverse transcription-quantitative polymerase chain reaction.
• Statistical analysis (Quade Nonparametric ANCOVA) to identify significant factors influencing sample representativeness.

Main Results:

• PMMoV RNA showed higher abundance and lower variability than SARS-CoV-2 RNA, serving as a reliable indicator of fecal contamination.
• 1-hour composite samples exhibited higher variability for both viruses compared to longer composite intervals.
• A 6-hour morning composite sampling window was identified as optimal for capturing representative SARS-CoV-2 RNA levels.

Conclusions:

• A focused 6-hour morning composite sampling strategy is a pragmatic and cost-effective method for wastewater-based epidemiology of SARS-CoV-2.
• This optimized sampling approach enhances data accuracy and reliability for community-level public health surveillance.
• Improved wastewater surveillance can lead to more informed public health decision-making during pandemics.