Wastewater Surveillance: A New Frontier for Public Health

June 18, 2024
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Wastewater surveillance sampling continues to provide valuable insights into the spread of infectious diseases.

While many people have pushed memories of the COVID-19 pandemic as far to the back of their minds as possible, variants of COVID continue to work their way through populations in the US and internationally.

Currently, Orange County officials in Orlando, Florida, report only a few cases of clinical infection, even though wastewater samples reveal that some COVID-19 variants are still very much present in Central Florida.

What’s changed for Orange County since the peak of the pandemic in 2022 is that at this time, omicron represents almost 100 percent of strains identified in wastewater surveillance samples obtained by Orange County utilities. While considered highly contagious, omicron symptoms tend to be milder than those of some other strains of COVID-19.

Orange County Mayor Jerry Demings recently confirmed that individuals hospitalized for a COVID variant “are being primarily infected by the delta variant.” This insight suggests that while omicron has been the most prominent variant in the Orlando area in recent weeks, infected people typically do not wind up in the hospital.

Why is Central Florida such a significant barometer for tracking the management of infectious diseases?

Although the area has a sizable population of more than 8 million residents, most importantly, it hosts hundreds of millions of visitors annually from all over the world.

The National Wastewater Surveillance System

In response to the COVID-19 pandemic, CDC launched the National Wastewater Surveillance System (NWSS) in September 2020. The NWSS was established to coordinate and support the nation’s capacity to monitor SARS-CoV-2 in wastewater.

Tracking infectious diseases through wastewater is not a new concept. The poliovirus was detected in wastewater sampling as early as 1939. However, the global pandemic of 2022 certainly brought a new emphasis on the importance of this type of wastewater testing. While the startup of NWSS was very grassroots, today the initiative includes more than 1,200 testing sites across the U.S.

Given the valuable information learned through NWSS wastewater surveillance testing, the CDC plans to expand the system to better understand antimicrobial resistance, foodborne illness, and infectious disease.

The CDC describes wastewater surveillance as “a new frontier for public health.” Wastewater surveillance (also called wastewater-based surveillance or wastewater-based epidemiology) tracks chemical markers by analyzing a population’s wastewater. The indicators tracked can be biological or chemical, which expands the use of wastewater surveillance beyond tracking disease and illness to include tracking illegal or pharmaceutical drug use.

From the CDC: Key public health advantages of wastewater surveillance include:‎

  • The ability to identify changing infection trends for SARS-CoV-2, on average, shows changes 4 to 6 days before those same trends are seen in clinical cases.
  • Cost and time efficiencies.
  • There is no dependence on the availability of COVID-19 testing and no limitations caused by only sampling people with access to healthcare or people seeking healthcare when sick.
  • Feasibility for implementation in many communities since nearly 80 percent of U.S. households are served by sewer systems.

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