Wastewater surveillance researchers identify tools to estimate how many people are represented in a sample

two people collect wastewater samples
Andrew Rainey and Amber O’Conner, doctoral students in environmental and global health and members of the Gator WATCH™ team, sample wastewater from a manhole.

By Jill Pease

Wastewater-based epidemiology is a valuable public health surveillance tool that has been used throughout the COVID-19 pandemic to track disease trends in a community over time. A team of investigators from the University of Florida College of Public Health and Health Professions has identified a population biomarker that will help scientists generate the most accurate disease trend results in their communities.

The team of scientists in the PHHP department of environmental and global health, including Ph.D. student Andrew Rainey and faculty members Anthony Maurelli, Ph.D., Joseph Bisesi, Ph.D., Tara Sabo-Attwood, Ph.D., and Song Liang, Ph.D., published their findings in the journal PLOS ONE.

For their study, the investigators, who are also members of UF’s Emerging Pathogens Institute, evaluated population normalization factors, which are used to determine the relative human fecal contribution in a sample. With this information, scientists can control for fluctuations in the population contributing to a wastewater sample throughout time while quantifying the SARS-CoV-2 wastewater concentrations.

The Centers for Disease Control and Prevention’s National Wastewater Surveillance System currently recommends four population normalization factors. These factors are the most common biomarkers used in wastewater-based epidemiology research and their use is critical for the accurate interpretation of COVID-19 wastewater data. Yet to date, there has not been a comprehensive assessment of which population normalization factors generate the most accurate disease trend results.

For their new study, the UF team analyzed a large CDC National Wastewater Surveillance System dataset of 182 communities in multiple states to assess the correlation between SARS-CoV-2 wastewater concentrations and reported COVID-19 cases after normalizing for the four recommended population normalization factors. They found that wastewater flow rate produced a significantly higher correlation with COVID-19 cases, when compared to the three other population normalization factors.

“These results show that wastewater flow rate is a simple and effective measurement that can be used to improve the strength and interpretation of wastewater-based epidemiology results,” the authors write. “We anticipate this work will contribute to future research on more accurate and effective methods for tracking the spread of COVID-19 and other infectious diseases.”