SARS-CoV-2 (the virus that causes COVID-19) and other respiratory viruses like influenza (Flu A and B) and respiratory syncytial virus (RSV) enter wastewater, or sewage, through the toilets and sinks of infected people. Monitoring respiratory viruses in sewage can provide an important early warning signal of increasing infections of various diseases; for example, it was used to detect polio spread in the 1930s and 1940s.
The Kentucky Wastewater Surveillance System (KYWSS) is part of the National Wastewater Surveillance System (NWSS). KYWSS is nicknamed “Cues” in the same way the NWSS program is known as “News”. A cue is a signal for actors to start saying or doing something. We think that wastewater surveillance can provide ‘cues’ for managing respiratory disease outbreaks before diseases like flu, Covid-19 and/or RSV are seen in your community so people can do what they can to lower their risk of becoming ill.
The Kentucky Wastewater Surveillance System (KYWSS) is a joint project of three divisions of the KY Dept for Public Health (KDPH): Public Health Protection & Safety (PHPS), Epidemiology & Health Planning (EHP) and the Division of Laboratory Services (DLS). Laboratories at both the University of Kentucky (UK) and the University of Louisville (UofL) assist KYWSS by analyzing samples from some of our sites. Collection sites are the sewage catchment area, or “sewershed,” served by a local wastewater treatment plant. UK collects and analyzes samples from both sewersheds in Lexington and those in the East Region: UofL manages samples for all five (5) of the Louisville sewersheds. KYWSS includes wastewater treatment plants (WWTPs) in regionally important sites such as university towns, military installations, tourism, and economic and medical hub cities to provide ample data for reliable wastewater-based sentinel epidemiologic data collection.
As part of the Centers for Disease Control and Prevention (CDC) National Wastewater Surveillance System (NWSS), KYWSS helps provide the public health infrastructure to monitor infectious diseases. Wastewater monitoring data can help local public health agencies identify outbreak trends early, direct prevention efforts to where they are most needed, and provide additional insight into disease spread that complements other public health surveillance data. Health departments, community leaders, and individuals can use wastewater monitoring data to make decisions about how best to protect their community.
How does this work?
Twenty-four (24) hour composite (combination of 1 sample/hour) samples are taken from influent (collected community sewage) before it enters a wastewater treatment plant (WWTP). The term 'influent' is used to describe the untreated wastewater that enters a wastewater treatment plant. Whether you live in an area with hundreds to hundreds of thousands of people sharing a WWTP, this sampling point increases personal privacy while actively monitoring for respiratory viruses. Laboratories analyze the samples using PCR (polymerase chain reaction), a technology that can identify specific viruses. Public health officials can compare these data with trends in respiratory disease reports to assist in public health communications.
KYWSS maintains a
dashboard that regularly reports wastewater viral activity in Kentucky. The KYWSS dashboard displays Wastewater Viral Activity Level (WVAL) for COVID-19, Flu A, and RSV. KYWSS does not examine any other viruses or substances. Data is presented as maps displaying sewersheds with each site’s most recent week’s WVAL as well as state and regional graphs showing a history of WVAL changes. To learn more about WVAL, visit the
NWSS About the Data page.
Why is this important?
Monitoring viral activity in wastewater gives public health officials the ability to identify changing infection trends for some viruses, on average showing changes well before those same changes in trends are seen in clinical cases Wastewater monitoring data can help local public health agencies identify outbreak trends early, direct prevention efforts to where they are most needed, and provide additional insight into disease spread that complements other public health surveillance data. Health departments, community leaders, and individuals can use wastewater monitoring data to make decisions about how best to protect their community.
Compared to other surveillance systems, wastewater testing:
• Can be more cost and time efficient.
• Does not rely on availability of COVID-19 or other disease testing.
• Captures viral activity even when healthcare access is limited, or if an infected person does not seek healthcare when sick.
• Protects privacy since sewersheds capture all public sewer in a community; hundreds to thousands of households and commercial sites contribute to the sewershed depending on size.
Why is this ‘sentinel’ epidemiology?
Sentinel means early warning. Wastewater monitoring is fast and efficient. Wastewater data can show changes in disease trends before trends are seen in clinical cases. This information can be used to prepare health care providers and hospital systems for upcoming increases in visits and hospitalizations and can help communities take timely and effective preventive action.
From toilet flush to results only takes about five to seven days. KYWSS tests 24-hour composite samples taken twice a week from the combined sewage flow from the community served (sewershed) before it enters the treatment process at your local wastewater treatment plant (WWTP). This type of influent wastewater testing provides anonymized information on community-level disease trends for hundreds, thousands, even tens of thousands of people depending on the size of sewershed.
How does KYWSS protect my privacy?
Because each sewershed is comprised of hundreds, thousands or even tens of thousands of households, schools, and businesses, detected viral fragments pose minimal ethical risks or threats to privacy. The Kentucky Wastewater Surveillance System will never sell or share influent samples with commercial third-party laboratories. KYWSS will never sell or share raw analytical data with commercial third-party laboratories. The KYWSS regularly monitors just four (4) respiratory viruses: influenza A and influenza B (Flu A & B), respiratory syncytial virus (RSV), and SARS CoV-2 (Covid-19).
How will KYWSS use this data?
Wastewater can detect infection in a community before symptoms are apparent. Unlike other types of public health reporting, wastewater surveillance (monitoring) does not depend on people having access to healthcare, visiting a doctor when sick or availability of testing for an infection. Instead of identifying a specific individual with disease, the results show whether respiratory disease is increasing or decreasing for the entire population serviced by a particular WWTP. Very often, wastewater signals can precede case reports by as much as 2-4 weeks. With this information, local health departments and healthcare providers can anticipate the potential for an outbreak or determine when an outbreak has passed.
The KYWSS dashboard shows wastewater detection of virus in raw sewage. We use the WVAL calculations to show when levels of virus in a community shift significantly up or down. Sometimes this means an outbreak is developing or resolving. Sometimes it can indicate the presence of an unexpectedly large flow of wastewater – for example, a large, multi-day basketball tournament, start of semester for a university, or holiday travel. In addition, individuals vary in the amount of respiratory virus that they shed in urine or stool; some people shed a lot, and others shed much smaller amounts even when sick. That’s why the baseline (average) calculation (what’s ‘normal’) for the community associated with a given WWTP is so important to understanding viral activity. We don’t even report the data until we have 6-10 weeks of data. We continue to re-calculate the baseline every week at every site for the first six (6) months and then update that every six (6) months thereafter.
Will KYWSS ever test for other things in wastewater?
Wastewater monitoring can be rapidly adaptable to track emerging health threats. The KYWSS is managed by the Countermeasures Unit in the KDPH PHPS. This Unit has responsibilities for disaster preparedness, so we have organized participating sites within each of the five (5) Kentucky “Areas of Operation” (West, South, Central, Northern/Bluegrass, and East). Each region is supported by Area Health Liaisons and Regional Epidemiologists who facilitate communication regarding wastewater-based epidemiology (WBE) for participating municipalities as well as local and district health departments (LHDs) use. In the event of a worrisome outbreak that involves KYWSS sites and Kentuckians need to know the extent of the outbreak, the KYWSS will request permission of participating municipalities before adding any additional test parameters addressing a specific threat.
How can I use the KYWSS dashboard?
Wastewater surveillance data are most useful when used with other surveillance data. When reviewed together, wastewater and other surveillance data can provide a more complete picture of disease spread within a community. The KYWSS Dashboard is designed to mirror the NWSS Dashboard while scaled to regions within the Commonwealth and individual sites. The KYWSS epidemiologist will work with the KDPH DEHP and the NWSS Data Analysis Group to integrate early wastewater signals with later observed cases of disease with the intent of developing better predictions for outbreak potential. The KYWSS Dashboard will work together with the Kentucky Respiratory Disease Dashboard to help Kentuckians track respiratory disease trends. Our hope is that this information will minimize respiratory virus-associated school and work closures and assist communities in optimally managing healthcare resources.
For questions regarding Kentucky Wastewater Surveillance System (KYWSS) or the KYWSS dashboard, please contact:
KYWSS@ky.gov
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