Literature Review of Wastewater Surveillance Tracking Pathogens
Project Introduction:
Wastewater surveillance is the most efficient and equitable approach to detecting and monitoring for an infectious pathogen within a population. The technique is free from the diagnostic biases seen with variable access to healthcare or testing across a community, particularly when vulnerable populations are involved. It is not impacted by clinical decisions to test or not test by a particular physician/provider, nor access (or lack thereof) to a diagnostic test that an individual patient may have. Rather, as has been seen across the world through many COVID-19 surges, WWS provides a universally applicable, leading indicator for a community when an infectious disease is beginning to circulate, while also providing the earliest indication that case rates are starting to decline on the other side of a surge. There are countless other infectious diseases for which WWS has been demonstrated effective, and many more for which it is likely to be important to informing population health decisions and healthcare capacity planning in the future.
Despite its promise, very little wastewater surveillance is underway in Santa Barbara County. The Santa Barbara Community Health Wastewater Collaborative was launched in late 2021 to bring together an array of public and private partners to build a regional wastewater surveillance initiative and bring the power of this tool to bear on a wide array of human and ecological health needs and opportunities. The Collaborative is a budding public-private partnership between UCSB, the County, City governments and utilities, major healthcare providers, local nonprofits and community members to build local capacity to equitably track COVID-19 and myriad other transmissible diseases through a regional wastewater surveillance program.
To move this effort forward, the Collaborative has formed and is growing a steering committee to govern its efforts, partnering with researchers and practitioners to meet immediate needs for monitoring COVID-19 outbreaks and the emergence of variants of concern, and working to secure the resources and partnerships needed to establish a regional wastewater surveillance lab and program. This initial website and the dashboard herein is the Collaborative’s first public facing initiative.
Santa Barbara Community Leader in this Effort
Image of Dr. Holden in her office.
Patricia (Trish) Holden is a Professor in the Bren School of Environmental Science & Management, University of California (UC), Santa Barbara, and Director of the UCSB Natural Reserve System. Her research spans environmental microbiology, microbial ecology, water quality, soil microbiology and processes, biodegradation, wastewater, and pathogens in the environment including SARS-CoV-2. Her education is in Civil & Environmental Engineering (B.S., University of Tennessee and M.S., Purdue University) and Soil Microbiology (Ph.D., and Postdoctoral, U.C. Berkeley), with eight intervening years in public and private sector civil / environmental engineering planning and design.
Relevant Academic Articles
Understanding the Factors That Affect the Detection and Variability of SARS-CoV-2 in Wastewater
Abstract: Wastewater-based surveillance (WBS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a promising complement to clinical testing as a means of assessing COVID-19 trends within a community. The objective of this project is to understand how the wastewater sampling designs impact the quantifiable SARS-CoV-2 genome in both centralized and decentralized wastewater collection and treatment systems. SARS-CoV-2 genome concentrations were analyzed in primary clarifier sewage influents and primary sludge samples from centralized wastewater treatment plants (WWTPs). Study of the decentralized wastewater collection and treatment system for SARS-CoV-2 genome detection was carried out in septic systems that serve the public restrooms at Zuma Beach, Malibu, California. The results showed that 24-hour composite samples can best represent the trends of SARS-CoV-2 concentrations in centralized WWTPs. The primary sludge samples had nearly 10 times higher concentrations of the viral genome, suggesting that sludge testing could provide greater sensitivity for SARS-CoV-2 detection. The decentralized wastewater management system also has the potential to be used as the access point for WBS. The pumping and hauling services can be used to easily access samples if direct sampling from septic tanks is not feasible.
Wastewater-Based Epidemiology: Global Collaborative to Maximize Contributions in the Fight Against COVID-19
Sources of Low Level Human Fecal Markers in Recreational Waters of Two Santa Barbara, CA Beaches: Roles of WWTP Outfalls and Swimmers
Abstract: Worldwide, fecal indicator bacteria (FIB) evidence coastal water contamination for which sources are unknown. Here, for two FIB-impacted Santa Barbara recreational beaches, hypothesized fecal sources were investigated over three dry seasons (summers) using nearly 2000 field samples of water (ocean, creek, groundwater), sand, sediments, effluent and fecal sources. In years 1 and 2, gull and dog feces were identified as the probable main FIB sources to surf zone waters, yet HF183 human fecal markers were consistently detected. Determining HF183 sources was therefore prioritized, via year 3 sub-studies. In lower watersheds, human and dog wastes were mobilized by small storms into creeks, but no storm drain outfalls or creeks discharged into surf zones. Beach area bathrooms, sewers, and a septic system were not sources: dye tracing discounted hydraulic connections, and shallow groundwater was uncontaminated. Sediments from coastal creeks and downstream scour ponds, near-shore marine sediments, and sands from inter- and supratidal zones contained neither HF183 nor pathogens. Two nearby wastewater treatment plant (WWTP) outfalls discharged HF183 into plumes that were either deep or distant with uncertain onshore transport. Regardless, local sources were evidenced, as surf zone HF183 detection rates mostly exceeded those offshore and nearshore (around boat anchorages). The presence of swimmers was associated with surf zone HF183, as swimmer counts (on weekdays, holidays, weekends, and during races) significantly correlated (p<0.05, n = 196) to HF183 detections. Besides comprehensively assessing all possible fecal sources, this study provides new explanations of chronic low-level human markers in recreational beach surf zones, suggesting likely lowest achievable HF183 thresholds.
Glossary
Wastewater surveillance - process of monitoring wastewater for contaminants. Amongst other uses, it can be used for biosurveillance, to detect the presence of pathogens in local populations, and to detect the presence of psychoactive drugs.
Tracking COVID-19 in wastewater - People infected with SARS-CoV-2 can shed the virus in their feces, even if they don’t have symptoms. The virus can then be detected in wastewater, enabling wastewater surveillance to capture presence of SARS-CoV-2 shed by people with and without symptoms. This allows wastewater surveillance to serve as an early warning that COVID-19 is spreading in a community. Once health departments are aware, communities can act quickly to prevent the spread of COVID-19. Data from wastewater testing support public health mitigation strategies by providing additional crucial information about the prevalence of COVID-19 in a community. (Sourced from the CDC).
Normalization - A statistical method to account for differences in variables such as wastewater flow rate and number of people served by a sewer system. In other words, normalization reduces excess variation (or “noise”) and helps account for things like changing population sizes or weather events that can impact wastewater. Normalized data can be compared over time and between different sites. Metrics presented on the dashboard page are based on SARS-CoV-2 viral RNA concentrations in wastewater that have been normalized using the pepper mild mottle virus (PMMoV). It is a plant virus belonging to the genus Tobamovirus in the family Virgaviridae caused by people eating peppers and their processed products, and is excreted from a large proportion of healthy human populations, but rarely found in animal feces. PMMoV was found to be the most abundant RNA virus in human feces, is globally distributed and present in various water sources in greater abundance than human pathogenic viruses, without substantial seasonal fluctuations. As the flow rate of sewage and the amount of fecal materials in sewage are quite variable, normalization needs to occur in order to compare across time. Thus, PMMoV is used to represent the amount of human fecal materials in sewage due to its prevalence in human population and high concentration in sewage. By dividing the concentration of SARS-CoV-2 by the concentration of PMMoV to obtain the ratio of SARS-CoV-2 versus PMMoV, we can eliminate the impacts of variable human fecal materials and sewage status during sampling. (Sourced from the CDC).