Community wastewater surveillance to determine COVID-19 viral loads made a splash during the pandemic as awareness of its usefulness spread.

Now, Halifax-based researchers are using tools and approaches gleaned from the pandemic to monitor other water systems and water-related health threats in Nova Scotia. 

“When we worked in tracking SARS-CoV-2, it was a very exciting time for us,” Dr. Graham Gagnon said in an interview. “There are few projects that I’ve worked on that have engaged the public so quickly and so profoundly with so many questions.” 

Gagnon is director of the Centre for Water Resources Studies (CWRS) and a Dalhousie University researcher. While looking for SARS-CoV-2 in wastewater at the onset of the pandemic, he and his team developed a method for measuring the virus. That tool is now commercially sold.

Although highly effective, Gagnon said the tool’s drawback is that it’s specific to SARS-CoV-2. Throughout the pandemic, he and his team have frequently found themselves fielding questions from media and members of the public about the ability to measure other pathogens, like norovirus or respiratory syncytial virus (RSV). 

“Our answer was normally, ‘Yes, we’re aware there’s other viruses that humans have. We can’t track them in wastewater at this time.’ And, of course, we’re in the middle of a pandemic so the urgency wasn’t as acute,” Gagnon said. 

“Last summer, as the cases of RSV and influenza increased, we received those questions more frequently.”

Help ensure safety of drinking and surface water

Their ability to more rapidly identify waterborne pathogens recently got a boost. The team received $1.1 million in Research Nova Scotia funding to purchase equipment that will allow them to analyze water samples themselves rather than sending them out of the province. 

“The foundational work completed as part of a pandemic response has provided additional opportunities to address a range of water issues important to Nova Scotia,” Stefan Leslie, CEO of Research Nova Scotia, said in a media release. “This work will not only continue to develop our capacity to monitor pathogens of concern in wastewater but will also help ensure safety of drinking and surface water.”

In a separate media release, Dalhousie University said the new equipment will allow for “timely analyses” of various water surveillance samples. It will also increase the current water surveillance laboratory’s capabilities.

Gagnon explained that research samples used to be sent to the Public Health Agency of Canada (PHAC) in Winnipeg. Due to the volume of samples received by the agency, wait times were often long.

“Sometimes it would be months of time lags. And if you’re collecting a sample at a wastewater facility or we were doing work at residences and at lakes, sometimes a full season would go by,” he said. 

“And then you go, ‘OK. Is the same person even living in this house or in this residence? Or the lake has turned over, it’s no longer summer, it’s now ice on the lake, and there’s no re-sample at that moment.” 

Algae blooms

Beyond wastewater surveillance, the team has been researching harmful algae blooms produced by cyanobacteria. Blue-green algae blooms can be lethal for pets and negatively affect human health.

The Nova Scotia Department of Environment and Climate Change has an information page about blue-green algae, encouraging people to be on the lookout for it between the months of May and October.

“In people, blue-green algae exposure when swimming can cause itchy, irritated eyes and skin. Swallowing or inhaling the water can cause headaches, fever, diarrhea, abdominal pain, nausea and vomiting,” the department notes. “Prolonged exposure can damage the liver.”

The surface of a lake is clouded by swirling blue-green algae.
A medium-density bloom of blue-green algae species in Nova Scotia near the shoreline of a lake. Credit: Nova Scotia Department of Environment and Climate Change

Climate change means many Nova Scotia lakes are experiencing algae blooms at a higher frequency and for longer periods. 

The CWRS team is interested in exploring whether they can look at algae blooms like they do viral signals to determine if there are connections within watersheds, or if unique circumstances exist in a particular watershed. 

“We’re very interested in taking our knowledge that we learned from the pandemic with wastewater,” Gagnon said. 

“We know that some of the lakes are impacted by runoff, whether it’s agriculture, whether there’s straight pipes, or whatever the scenario might be… and just trying to understand whether or not what we observed in sewer systems is observable in our lakes and making sure that the safety of these lakes are to a standard of care that Nova Scotians hope and aspire them to be.”

Gagnon expects they’ll soon be able to at least begin to answer some of the questions posed to them in the past.

‘Uniquely placed to take on’

He said he was working in the town of Lunenburg several years ago when the mayor at the time was being challenged about wastewater outfalls. He recalls being asked questions he wasn’t equipped to answer at the time.

“This, I think, starts us down a path to get to the questions the public were asking us three or four years ago. There weren’t many labs really at all in the world that could answer the questions that the public was asking of the mayor,” he said. 

“I see this as something that we are going to be uniquely placed to take on. Really important questions around lakes, the health of our lakes, the health of our wastewater systems. And in a way that very few international labs can.”

The research group is now working with community groups to sample a handful of identified lakes in HRM for different biological species.

“I’m hopeful as early as the end of the summer we’ll have new information for the city and the community groups that engage with the city to try to help answer those questions that are really hard to get at,” he said. 

“I don’t think we’ll have all the questions answered, but we may have methods developed or we may have new clues that we didn’t have before.”

The technology may also be useful in helping optimize water treatment plant efficiency. Gagnon said many wastewater treatment systems operate biologically, meaning they use bacteria to degrade organic material.  

“If you have the wrong cluster of organisms taking up space, you may be wasting energy. You actually want the organisms that are going to quickly degrade organisms to be there,” he said.

“That will… just make much more efficient operations.”

Wastewater surveillance increasing rapidly

An article published in the Journal of Travel Medicine last month noted the role of wastewater surveillance “is increasing rapidly” as a way to assess global transmission of not only SARS-CoV-2 and its variants, but other pathogens. 

The authors highlighted the need to establish a global wastewater surveillance consortium for future pandemic preparedness. 

“We propose here that wastewater surveillance should be incorporated into such international and regulatory framework as a global infectious disease surveillance system,” the authors wrote. 

“Urban wastewater data generated in a geographical region can be used to prepare appropriate infection control measures in another geographical region. Furthermore, aircraft wastewater genomic surveillance can potentially track the transboundary pathways of emerging viruses.”

Monitoring of aircraft wastewater is already happening in a number of countries, including Canada. Several of those countries have also established an international wastewater monitoring consortium by open data sharing of SARS-CoV-2 in both urban and aircraft wastewater.

In February, the Halifax Examiner reported on a group of Canadian researchers at the forefront of improving wastewater surveillance in planes and airports.

They developed a model that standardizes data collection, reporting, and storage of wastewater, making it easier for users to share and compare data. Their model has been adopted by 27 countries and is being recommended by the European Union. 

That research group is also investigating the addition of surface testing (swabbing) in airports and on airplane surfaces.

Opens up opportunities

Gagnon said the ability to sequence samples onsite with their newly acquired equipment puts CWRG in a unique position among many research teams doing similar work.

“With this investment, we’d be among the few that have these types of tools right at their fingertips,” he said.

One of the lessons Gagnon has learned from the pandemic is that most Nova Scotians have a “profound experience” with water. He said he’s “thrilled” his team can help contribute to people experiencing the province’s water safely.

“I think the public understands water systems,” he said. 

“We have a province that has many septic tanks, many wells, we have many lakes that people connect with water, and beaches. So we’re a community of people that engage with water in many, many ways… This opens up opportunities to pursue this research even further.”

A smiling white woman with long straight dark blonde hair and bangs, with half her face in dramatic shadow

Yvette d'Entremont

Yvette d’Entremont is a bilingual (English/French) journalist and editor, covering the COVID-19 pandemic and health issues. Twitter @ydentremont

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