A community’s sewage holds clues about its COVID-19 burden. Over the course of the pandemic, wastewater surveillance has become an increasingly popular way to try to understand local infection trends.

Microbiologists Susan De Long and Carol Wilusz met and became wastewater aficionados in April 2020 when a grassroots group of wastewater treatment plant operators asked them to develop and deploy a test to detect SARS-CoV-2 in samples from the sewers of Colorado. De Long is an environmental engineer who studies useful bacteria. Wilusz’s expertise is in RNA biology. Here they describe how wastewater surveillance works and what it could do in a post-pandemic future.

Wastewater surveillance takes advantage of the fact that many human pathogens and products of human drug metabolism end up in urine, feces or both. The SARS-CoV-2 virus that causes COVID-19 shows up in surprisingly large quantities in feces of infected people, even though this is not a major route of disease transmission.

To figure out whether any pathogens are present, we first need to collect a representative sample of wastewater, either directly from the sewer or at the point where what engineers call “influent” enters a treatment plant. We can also use solids that have settled out of the wastewater.

Technicians then need to remove large particles of fecal matter and concentrate any microbes or viruses. The next step is extracting their nucleic acids – the DNA or RNA that holds the pathogens’ genetic information.

The sequences contained in the DNA or RNA act as unique bar codes for the pathogens present. For instance, if we detect genes that are unique to SARS-CoV-2, we know that the coronavirus is in our sample. We use PCR-based approaches, similar to those used in clinical diagnostic tests, to detect and quantify SARS-CoV-2 sequences.

Characterizing the nucleic acid sequence in more detail can provide information about viral strains – for instance, it can identify variants like omicron BA.2.

Currently, the vast majority of wastewater surveillance efforts are focused on SARS-CoV-2, but the same techniques work with other pathogens, including poliovirus, influenza and noroviruses.

Before the pandemic, one application was monitoring for rare poliovirus outbreaks in areas where polio vaccination is ongoing. Wastewater can also be monitored for signs of various drugs to give insights into the level and type of drug use in a population.

During the pandemic, the U.S. Centers for Disease Control and Prevention developed the National Wastewater Surveillance System specifically to track SARS-CoV-2 across the country. Over 800 sites report data to this NWSS system, but not all states and counties are currently represented.

Many state agencies, like the Colorado Department of Public Health and Environment, and cities, like Tempe, Arizona, have their own dashboards for reporting data. Some companies performing wastewater analysis report data on their own dashboards, too.

In our opinion, the NWSS represents an exciting first step in monitoring population health through wastewater. Similar systems are being established in other countries, including Australia and New Zealand.

SARS-CoV-2 levels in wastewater from large populations are an excellent indicator of the infection level in a community. The system automatically monitors everyone who lives in the sewershed, so it’s anonymous, unbiased and equitable. Importantly, it is also impossible to track the infection back to a particular person, household or neighborhood without taking additional samples.

Wastewater surveillance doesn’t rely on the availability of clinical tests or people reporting their test results. It also picks up asymptomatic and pre-symptomatic cases of COVID-19; this is critical because people who are infected but don’t feel sick can still spread COVID-19.

In our opinion, wastewater testing is increasingly important as more COVID-19 tests are done at home. And because vaccination has also led to more mild and asymptomatic cases of COVID-19, people may be infected without getting tested at all. These factors mean that clinical case data are less informative than earlier in the pandemic, while wastewater data remains a consistent indicator of community infection level.

So far, you can’t accurately predict the number of infected individuals in a community based on the level of virus in its wastewater. The stage of someone’s infection, how their body responds to the virus, the viral variant, how far a person was from where the wastewater sample was taken, even the weather can all affect the amounts of SARS-CoV-2 measured in sewage.

But scientists can infer relative changes in infection rates. Watching viral levels go up and down in sewage provides a glimpse of whether cases are rising or falling in the community as a whole.

Because SARS-CoV-2 can be detected in wastewater days or even weeks before outbreaks occur, wastewater monitoring can provide an early warning that public health measures may be warranted. And trends in the signal are important – if you know levels are rising, it may be a good time to reinstitute a mask mandate or recommend working from home. At present, public health officials use wastewater monitoring data along with other information like test positivity rates and the number of clinical cases and hospitalizations in the community to make these kinds of decisions.

Data from sequencing can also help detect new variants and monitor their levels, allowing health responses to take into account the characteristics of the variant present.

In smaller populations, such as in college dormitories and nursing homes, wastewater monitoring can detect a small number of infected people. That can sound the alarm that targeted clinical testing is in order to identify infected people for isolation. Early detection, targeted testing and quarantining are effective at preventing outbreaks. Rather than using clinical testing for routine monitoring, administrators can reserve disruptive clinical tests for times when SARS-CoV-2 is detected in the wastewater.

Widespread and routine use of wastewater monitoring would give public health officials access to information about the levels of a range of potential infections in U.S. communities. This data could guide decisions about where to provide additional resources to communities, like holding testing or vaccination clinics in places where infection is on the rise. It could also help determine when interventions like masking or school closures are necessary.

In the best case, wastewater monitoring might catch a new virus when it first arrives in a new area; an early shutdown in the very localized area could potentially prevent a future pandemic. Interestingly, researchers have detected SARS-CoV-2 in archived wastewater samples collected before anyone had been diagnosed with COVID-19. If wastewater monitoring had been part of the established public health infrastructure back in late 2019, it could have provided an earlier warning that SARS-CoV-2 was becoming a global threat.

For now, though, establishing and operating a national wastewater surveillance system, particularly one that includes building-level monitoring at key locations, is still too costly and labor-intensive.

Ongoing research and development efforts are trying to simplify and automate wastewater sampling. On the analysis side, adaptation of PCR and sequencing technologies to detect other pathogens, including novel ones, will be vital to take full advantage of such a system. Ultimately, wastewater surveillance could help support a future in which pandemics are far less deadly and have less social and economic impact.

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Susan De Long, Associate Professor of Civil and Environmental Engineering, Colorado State University and Carol Wilusz, Professor of Microbiology, Immunology and Pathology, Colorado State University

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There are thoughtful and meaningful things to do to celebrate new mothers on Mother’s Day.

Mothers with young children have lower levels of leisure and physical activities than the rest of the population, which puts their physical and mental health at risk. So the gift of sleep, time, self-care (“me time”) and a message of what a remarkable job she is doing may be what she needs most.

We’re a team of researchers who have studied the life-changing transition to motherhood for nearly 10 years. Our research has examined how motherhood enriches women’s lives at the same time as we challenge society’s notion of being a “good mother.” The role of policy (maternity leave legislation, childcare, access to leisure services) in shaping women’s experiences has been a central focus.

Similar to other research findings, in a recent study currently undergoing peer review, the new mothers we worked with sought out leisure and physical activities to minimize stress, decrease their anxiety, increase self-esteem and navigate their new mothering identity. The women’s participation gave them a sense of freedom and control over their lives.

For example, for some mothers, running on their own provided an opportunity to carve out time for themselves. For other mothers, running with their baby in a stroller helped them develop a sense of family.

But the reality is that postpartum activities are not accessible to all women.

In our recent study, we worked with new mothers from pregnancy to 18 months post-birth. We found that during pregnancy the women had unrealistic expectations of what life would be like, in contrast to the realities that they faced after the baby was born.

This included frustration about how much time they actually have to participate in leisure and physical activities. It also included disappointment about the type and intensity of activities they could return to — especially when considering their recovering postnatal bodies (for example, C-sections, general fatigue). The data also suggested that returning to work poses an additional challenge to women and successful leisure and physical activity engagement.

In western societies, “good mothering” practices are informed by an intensive mothering ideology that is informed by middle class and white values. It embodies motherhood as child-centred, emotionally absorbing and self-sacrificing. Compared to previous generations, mothering now extends beyond the provision of children’s safety and well-being. Mothers are expected to maximize their children’s growth and development. Participation in organized programs is one way to do this (for example, mommy and me swimming).

These societal expectations of “good mothering” often leave new mothers feeling unprepared, disappointed and fearing failure. However, research has shown that having more realistic expectations predicts better adjustment for mothers, including decreased depression.

Our research on parental policies found that they privilege paid work while reinforcing a socio-economic hierarchy in which only some mothers are able to access the benefits. This can affect women’s chances for improved health and well-being.

New mothers in our recent study who were self-employed were unable to access formal maternity leave policies. Consequently, they had reduced participation in leisure and physical activities — on their own or with their baby. This led to feelings of failure as a mom and in their careers.

Women in precarious employment who did not qualify for maternity leave programs also reported difficulties. Many community recreation programs are user pay, which excludes women of lower socio-economic status.

Although financial assistance may be offered for organized recreation programs, research has highlighted the humiliation of having to publicly declare or prove their low-income status. Other research points to the fear of going out in unsafe neighbourhoods in order to access community programs and services.

The COVID-19 pandemic has also disproportionately affected low-income mothers. The new mothers in our recent study talked about the high cost of transportation and difficulties using public transportation with a stroller. Consequently, many women feel judged and vulnerable from the outset of being a mother.

Generally, the stories from new mothers who qualified for maternity leave revealed that they had more time, money and choice of leisure and physical activities that they could access than mothers who did not qualify. Yet, they still have reduced income and higher costs with the arrival of the new baby. They also had to overcome challenges such as the stigma of breastfeeding in public spaces or the inability to participate in leisure and physical activities without their baby.

Social relationships play an important role in facilitating new mothers’ participation in their own leisure and physical activities.

Family support networks helped the mothers in our most recent study to resist the notion of self-sacrificing motherhood and to find time for themselves. The mothers’ partners and their extended family members (for example, mother, father-in-law) were important support networks to look after the baby. These support networks helped the mothers schedule and find much-needed time for themselves.

New mothers face challenges with their return to leisure and physical activities after the birth of a child. But it is clear that with support such as parental leave and family support, these activities can help them negotiate the difficult transition to motherhood and improve their health and well-being.

Dawn Trussell, Associate Professor of Sport Management, Brock University's Chancellor's Chair for Research Excellence, Brock University; Jennifer Mooradian, Research Assistant, Faculty of Applied Health Sciences, Brock University; Shannon Hebblethwaite, Associate Professor of Applied Human Sciences, Concordia University, and Stephanie Paterson, Professor, Political Science, Concordia University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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