By candace.tyler in Stories May 10, 2024

Wastewater Surveillance in Las Vegas

How wastewater epidemiology is reshaping public health tools and messaging for millions of residents and tourists alike.

Cassius Lockett holds a doctorate in epidemiology from the University of California, Davis, and is the Deputy District Health Officer — Operations for the Southern Nevada Health District (SNHD), which serves unincorporated Clark County and the incorporated municipalities within the county, including the city of Las Vegas. Kimberly Franich holds a master’s in public health from the University of Nevada, Las Vegas, and is Communicable Disease Manager for SNHD.

Together, the two specialize in the oversight of disease surveillance,  investigation, and subsequent evidence-based disease intervention  strategies and disease control measures for the county. They work to  safeguard the health of more than 2 million residents and millions of  tourists in Las Vegas and beyond.

SNHD has been part of wastewater surveillance for SARS-CoV-2 in  Southern Nevada since the science emerged early in the pandemic,  working with the University of Nevada, Las Vegas, Southern Nevada  Water Authority, and the Desert Research Institute. Their work with  WastewaterSCAN to monitor SARS-CoV-2 and other infectious diseases  began in May of 2023 to complement the area’s current wastewater  monitoring program. The program acts as an early warning system for  potential COVID outbreaks showing up in the sewage flowing through  Clark County’s six treatment plants.

“Using heat maps, we quantify the viral load based on specific variant  types. Our optimism lies in the system’s potential to identify even the  BA.2.86 variant,” Lockett explained.

Franich works closely with SNHD’s Office of Informatics and  Epidemiology to better understand how wastewater can be used for  public health messaging. Her role is to respond to communicable and  infectious disease, whether that means disease investigation, strategic  planning, or preventative messaging.

“We have limited resources,” she says. “So, we use wastewater data in  collaboration with the other additional information to more effectively  communicate to populations most at risk, but also validating the relative  success of our interventions.”

An Important Transition

SNHD’s transition to relying on wastewater-based epidemiology (WBE) for SARS-CoV-2 monitoring has been game-changing.
“We have high confidence in wastewater data,” Franich puts it bluntly.

In particular, WastewaterSCAN’s rigorous science gives them confidence that what they are seeing in the wastewater data is happening in the community. Lockett finds the genomic sequencing to be his most important tool. He uses the data generated to communicate to the community and leaders, monitor the appearance and spread of new variants, and, in particular, understand which pathogens have a high pathogenicity — the greatest risk of mortality or hospitalization.

“We have pivoted exclusively to relying on wastewater epidemiology to guide us in the future. We’re in the midst [of] redoing our reports to the public,” Lockett
says. “We download charts right from WastewaterSCAN and show whether infections are high, medium, or low. That’s all I care about is ‘high, medium or low’ in the wastewater. It becomes super easy for me to communicate.”

Beyond COVID

The partnership with WastewaterSCAN has contributed to Clark County’s ability to now monitor for 11 infectious diseases in the community. During the national mpox outbreak in 2022, the team harnessed WBE to monitor and oversee response to elevated levels of mpox at the University of Las Vegas, Nevada, and also has been tracking another pathogen — norovirus — throughout Clark County, which historically experiences three to four “significant” outbreaks each year.

“Looking ahead, we recognize the immense utility of this system in monitoring influenza, RSV, and human metapneumovirus,” Lockett said. “Particularly noteworthy is the prevalence of RSV in our community, warranting timely alerts to fortify preventive measures, including vaccination campaigns.”

Lockett and Franich also see value in using WastewaterSCAN data to help inform their public-health messaging for the respiratory virus season and the “trifecta” of influenza, RSV, and COVID-19, as Lockett calls it. “We want a better understanding before we communicate out to any kind of high level officials or even the public what those impacts might look like.”

Data Dependent

While WastewaterSCAN’s science is impressive and trusted, Lockett and Franich find the simplicity of collection and, especially, the easy-to-grasp data interpretation and visual presentation to be among WastewaterSCAN’s most valuable tools. How the data are presented sets the program apart and makes Lockett’s and Franich’s job communicating to officials and to the public easy and impactful.

“The dashboards and the heat maps are a key value add,” Franich says. “We are delighted the system is driving towards using a methodology that can be easily understood by the public. This helps with policy-making, public communication, and reporting at the local, state, and federal levels.”

“Everyday people are aware of the science,” Lockett says. “They are very interested in how the data is being used as a public health tool. That’s really helpful at an individual level as citizens look to the dashboard to make personal decisions and by public health departments as they make recommendations for the community.”

“I think our community has been pretty receptive of incorporating this tool in our surveillance, and wastewater data makes it easy to communicate changing trends, even just amongst our team,” Franich says.

Unexpected Upsides

One of the lesser-appreciated benefits of wastewater monitoring over traditional surveillance like clinical testing data, hospitalizations, and mortality figures, is that wastewater collection is “very, very, very flexible” in its sampling administration, Lockett says.

SNHD already has tapped into wastewater science to engage in expanded disease monitoring on its own, beyond the scope of what WastewaterSCAN
is doing.

“We can pretty much collect from anywhere. We were able to sample, for example, around the bars and pubs near UNLV. We’re at airports. We were at a
hospital. It’s just so flexible and goes beyond traditional surveillance.”

In a city like Las Vegas, with a large resident population, but also high volume of tourists, that flexibility is a luxury few epidemiologists can pass up. Lockett and Franich are combining wastewater data with multiple traditional data sources to help them prepare for destination events, like the annual Consumer Electronics Show (CES), the largest tech conference in the world, that draw even more people to Las Vegas each year.
“There’s all kinds of different opportunities to go beyond just COVID to make sure that wastewater surveillance will have a growing role in pathogen detection in these populations,” Lockett says.

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