Wastewater-based Epidemiology: A Collective Effort to Track COVID-19

March 2, 2022
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Wastewater-based epidemiology has been used for many years to understand the spread of various diseases, drugs, and contaminants throughout communities in the world. Usually collected at sewage treatment plants and analyzed for trace chemicals and biomarkers, wastewater can indicate that the local population has been exposed to or consumed hazardous chemicals or pathogens. Modern examples of WBE go back to at least 1954, but we can look back to the 1800s and our friend, Dr. John Snow, for its beginnings.

 While Dr. Snow didn’t have access to the testing capabilities we have today, he was able to connect cholera to water contamination and saved numerous lives. By using what we now know as WBE, he identified locations that correlated with contaminants and water flow to not only figure out where water pumps were contributing to illness, but also to identify the source of the contamination. Later research by Dr. Snow explored the water companies in the area and determined that the source of the contamination was the Thames River.

 Modern-day WBE has been used around the world to:

 Currently, researchers are trying to detect the SARS-CoV-2 virus, which causes COVID-19, in wastewater by looking for the virus’s RNA. People infected with SARS-CoV-2 can shed the virus in their waste even if they don’t have symptoms, so mapping the presence of SARS-CoV-2 in wastewater can help local health departments understand what may be happening before it would otherwise be detectable. While it is not possible to determine the number of individuals infected with the SARS virus, mapping these data can provide a warning that COVID-19 is spreading in a community before a significant outbreak occurs.

 Collective Research

 WBE requires a collective effort between various public, private, and academic organizations to detect and manage infectious disease transmission in communities. Collective efforts to coordinate research and responses to the pandemic using GIS and other tools began in early 2020. Many experts saw the potential for collaborative epidemiological surveillance of the SARS virus at the global, regional, and local levels.

 Dr. Aaron Bivins founded the WBE Collaborative in March 2020, while in a postdoctoral position at Notre Dame. The collaborative is a partnership of the Sewage Analysis CORe group Europe network with the Global Water Pathogen Project to coordinate and promote the efforts of research groups undertaking WBE for SARS and COVID-19.

 The COVID-19 Healthcare Coalition was established In March 2020 as a coordinated response to the COVID-19 pandemic. Public and private organizations including healthcare organizations, technology firms, nonprofits, academia, and startups came together to find ways to support organizations, communities, and individuals impacted by the Pandemic. Now coordinated by MITRE, the more than 900 member organizations of the coalition support many aspects of the pandemic response, including evaluating testing technology and providing analytics, modeling, and simulation.

 The United States Centers for Disease Control and Prevention further encouraged the use of WBE to monitor and understand the spread of SARS-CoV-2 in the United States by launching the National Wastewater Surveillance System in September 2020. The CDC developed NWSS to build the nation’s capacity to track the presence of SARS-CoV-2 in wastewater samples collected across the country. By late March 2020, wastewater samples were being collected and analyzed around the world.

 In April 2020, the Missouri Department of Natural Resources contacted the Missouri Department of Health and Senior Services Bureau of Environmental Epidemiology to see if the bureau would be interested in testing wastewater for signs of SARS-CoV-2. According to Jeff Wenzel, bureau chief, they started with nine sites to determine if they could:

  •  Detect SARS-CoV-2.
  • Develop appropriate lab methods.

 Once they determined that they were successful, the Department of Health and Senior Services grew the testing network to over 100 community locations, with an additional 100 locations elsewhere. The project continues to grow as new community testing sites are added, and now includes the University of Missouri as a partner. The university is also one of the 335 NWSS partners.

 Why GIS?

 “...A map-based view has proven compelling and informative—letting people know whether things are getting better or worse in their area,” said Dr. Este Geraghty, the chief medical officer and health solutions director at Esri. “Scientific and spatial analysis will continue to surface the patterns and anomalies arising from the ongoing global spread of this outbreak, and mapping will aid epidemiologic understanding of those patterns and targeted actions.”

 At the beginning of the pandemic, Johns Hopkins University was one of the first to release comprehensive maps showing where COVID-19 was most prevalent. Not too long after the JHU map became widely used, government agencies at all levels stood up their own maps and dashboards. Maps have since been the way we have come to understand how SARS and COVID-19 has affected the world.

 DHSS has used GIS since 1997, finding it a valuable management tool for policy making and resource management in the state. According to Jeff Patridge, GIS specialist at the Missouri Office of Geospatial Information, GIS has been an essential part of the collaboration between the State of Missouri and the various local agencies and other organizations around the state that are collecting and testing wastewater samples. “...The technology has allowed us to improve communication… and has also improved collaboration,” Patridge said. Partridge explained that while some places in the state have GIS, some still don’t; the fact that they have collaboratively established reporting standards and all provide information to his office, which is then mapped, allows everyone to see the patterns and trends. OGI established a storymap and several dashboards using Esri software to help agencies and the public see what is happening in their communities and around the state.

 Dr. Geraghty summed up the situation by pointing out that using spatial tools is important because modeling and spatial analysis “offer something special that you just don't get with regular tools.”

 More Collective Research and Collaboration

 As the pandemic continues, we see many examples of public, private, and academic collaborations, all focused on WBE and mapping. Local jurisdictions are partnering with other local and regional organizations to collect, analyze, study, and identify the existence of SARS-CoV-2 in communities, and to help predict outbreaks of COVID-19.

 The City of Tempe, another NWSS partner, started using WBE and GIS in 2018 to study opioid use. In the case of opioids, it is possible to tell the difference between “raw” opioids that may have been medications flushed into the wastewater and metabolites that are the result of illegal drug use. The city collected wastewater samples and compared them with EMS calls for service data related to probable opioid overdose calls. After the city put out a map of the study, researchers at the Arizona State University’s Biodesign Institute joined the city in a joint funding request to the city’s Innovation Fund to do further research. But, “when COVID hit, we pivoted fast,” said Dr. Stephanie Deitrick, Enterprise GIS & data analytics manager at the City of Tempe.

 The five existing sites used for wastewater testing of opioids started testing for SARS-CoV-2, and two new sites were added. “...As we started to watch the data and started to watch the trends, it actually looked like the wastewater turned into a leading indicator for what the infection rates were going to look like,” Dr. Deitrick said. This was particularly important when Site 6 was added. The new site was implemented before people were really starting to get tested, and there weren’t vaccines yet. The site is located near the Tempe campus of Arizona State and includes some large high-rise student apartments and residential areas with a high population of underserved populations, including low-income, older, and younger people. The area also has a large percentage of children living in poverty. It was a “recipe for disaster for people that would have fallen through the cracks, even outside of COVID,” Dr. Deitrick said. Another challenge was that this community tended to have larger household sizes, so if someone did get sick, there would be no way for them to isolate.

 Similarly to the State of Missouri, the City of Tempe has used GIS and GIS-related tools to map their data and create models. The city is using Esri’s ArcGIS Hub tools to share data, maps, and dashboards to engage the community. At the local level, the city is also using their data and models to reach out to the community directly. Dr. Deitrick’s team looked at the results of the testing being conducted and realized that Site 6, as small as it is compared to the other sites, had a disproportionately high amount of SARS-CoV-2 in the wastewater. “It was one of those things where we wouldn't have realized there was a problem, if we hadn’t seen that a very small area had high numbers,” Dr. Deitrick said. The data told the story. The larger numbers of SARS-CoV-2 plus the demographics and lack of access to resources mobilized the city to work with businesses and community leaders to do direct outreach in the affected community, including going door to door to hand out masks, hand sanitizer, items for children, and educational materials in multiple languages.

 One Health

 One Health is the idea that people’s health is closely connected to the health of animals and our shared environment—that these three facets of health intersect and that, in order to understand health and health care, we must use a collaborative, multisectoral, and transdisciplinary approach at the local, regional, national, and global levels.

 Dr. Geraghty believes that wastewater surveillance is a good example of the idea of One Health. “The environment is not simply the natural environment,” Dr. Geraghty said. “It's the infrastructure; it's the built environment… Municipalities have been testing the wastewater for 50 years or more. It’s not really a new concept, but [with WBE] it’s much more visible... and given the current situation, it's becoming more mainstream.”

 NWSS participation is expected to grow as health departments and public health laboratories develop wastewater surveillance coordination, epidemiology, and laboratory capacity. According to the CDC, as of August 2021, 43 public health departments are using CDC funds to support wastewater surveillance activities, 32 state and local health departments are participating in the public health community of practice, and nine states are reporting data to NWSS.

Wastewater-based epidemiology “provides a robust, highly adaptable platform for community-level disease surveillance that can be expanded to collect data on multiple pathogens,” Dr. Geraghty said.

Understanding the spatial and temporal trends of viruses like SARS-CoV-2 and other water-borne pathogens will continue to be valuable to our global and local communities, even beyond the current pandemic. Connecting WBE with supplementary information, other indicators, and available geospatial data related to demographics, emergency services, and many others will be critical as a public health tool, as humans continue to interact with each other on a global scale.

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