Sewer system sampling for wastewater-based disease surveillance: Is the work worth it?

Area of Science:

• Environmental microbiology
• Public health surveillance
• Molecular epidemiology

Background:

• Wastewater-based disease surveillance relies on influent sampling, but sewer network processes can dilute pathogen signals.
• Understanding SARS-CoV-2 dynamics within sewer systems is crucial for accurate public health monitoring.

Purpose of the Study:

• To investigate SARS-CoV-2 concentration dynamics in three distinct sub-catchments.
• To compare the efficacy of sub-catchment sampling versus wastewater treatment plant (WWTP) influent sampling for disease surveillance.

Main Methods:

• SARS-CoV-2 RNA quantification in wastewater samples from selected sub-catchments and the main WWTP influent.
• Analysis of virus concentrations relative to population density and urban characteristics within sub-catchments.

Main Results:

• Sub-catchment sampling identified higher SARS-CoV-2 concentrations per inhabitant compared to WWTP influent samples.
• Localized sampling revealed virus concentrations missed by aggregated influent monitoring.
• Sewer network sampling provided spatially resolved data on SARS-CoV-2 circulation.

Conclusions:

• Sub-catchment wastewater sampling is more sensitive for detecting localized SARS-CoV-2 hotspots.
• This approach improves the precision of wastewater-based epidemiology for identifying high COVID-19 incidence areas.
• Targeted sewer sampling offers significant advantages over general WWTP influent sampling for public health insights.