Four Questions Answered About Monitoring Coronavirus Wastewater

Researchers around the world are testing wastewater from the SARS-CoV-2 virus and hope that what goes down the drain will serve as an early warning system for COVID-19 infection in the community.

Environmental Engineer Kyle Bibby Is coordinating a national research network hosted by the National Science Foundation, aimed at helping scientists pool research in this area. Here he describes the relationship between sewage and viruses and how researchers hope to transform raw measurements into useful public health information in the end.

How do you monitor bacteria in wastewater?

This idea has received a lot of attention lately, but it’s not new. Scientists are looking for pathogens in sewage At least since the 1940s, Especially poliovirus.

The overall concept is fairly simple. Infected people excrete pathogens, which are flushed down the toilet or into sewers. Pathogens, or fragments of their genes, pass through the community’s sewer system Processing plantIf its presence can be detected by careful sampling.

About two-thirds of people infected with SARS-CoV-2 Excretion of coronavirus in feces.. In the treatment facility, molecular tools can be used to monitor viral RNA wastewater.

Although there are no real standards yet, most approaches concentrate the wastewater sample to some extent, increasing the likelihood of detecting RNA. We are looking for a small sequence of a single SARS-CoV-2 gene rather than a complete intact genome.

The RNA fragment we are measuring is too small to be physically captured directly. Therefore, they are usually hooked using another trick called electrostatic interaction. Attach the RNA to something like a filter or use other chemicals to agglomerate.

Then quantify the amount of viral RNA in the sample.

It is important to realize that it is not possible to directly infer how many people in the community have from measurements made in wastewater Coronavirus— At least not yet.

What does the presence of the coronavirus tell you?

When looking for viral RNA in wastewater, you can set three related goals. The first is direct monitoring. Basically, does the virus exist, yes or no? This is perhaps the most promising for small confined communities, schools, dormitories, prisons, nursing homes and more. This requires sampling directly from the facility’s sewer. For example, University of Arizona Detected the presence of asymptomatic infected students Test wastewater from campus residences.

The next potential application is trend monitoring. Is the apparent concentration of virus increasing? This may indicate an increase in infections within the community.

And a third application (probably in the furthest place) applies the measurements directly to estimate the number of infected individuals in the community.

There are many uncertainties about how and for how long an infected individual excretes this virus. Viruses are reportedly volatile. One person can become ill with COVID-19 and excrete 100 copies of the coronavirus genome per gram of stool. Another individual may be excreting 100 million copies per gram of stool, a huge difference.

The overall vision is that wastewater monitoring can inform all types of public health interventions and disease monitoring programs. It can complement clinical surveillance, which often lags the true disease level of the community.

Is the wastewater itself a pollution risk?

Wastewater monitoring has been commonly used to detect pathogens that spread through the oral route rather than the respiratory route that is believed to be responsible for SARS-CoV-2 infections. There is a discussion about Whether the coronavirus can spread through water.. I think it’s plausible, but it’s certainly not the main route of transmission and has not yet been proven.

There are several reports that infectious virus was excreted in the stool, It seems that the majority is disabled After leaving the patient’s body. So I really don’t believe that coronavirus in wastewater should be of great concern to the general public.

For wastewater processors, it’s probably a bigger concern. But the consensus is that standard personal protective equipment for treating wastewater is adequate to control the coronavirus. Except for a pandemic, wastewater can always contain other infectious agents.

But imagine swimming on the beach downstream of the processing plant. You don’t have to worry about the viral genome debris left in the water. Concerns are infectious viruses, and we have never seen infectious viruses transmitted to sewage treatment plants.

What are the issues to be solved?

It’s a misconception to think that this technique is ready for use. There are still many open sciences on how to do it well.

It’s not appropriate to think of it as everyone in the community testing COVID-19. Limitations of detection have various problems, including the acquisition of complex samples that incorporate wastewater all day long, and, of course, the fact that many sick people cannot detect viral RNA without excretion. Poor results from wastewater treatment do not really mean that zero people in the area carry the coronavirus. Therefore, wastewater monitoring is subtly different from clinical diagnostic tools.

I’m worried that the city’s Department of Health will get wastewater data from a contract lab. Suddenly, we believe that everything is safe and the coronavirus cases are low or over-extrapolated in the area. This did not mean that we couldn’t immediately use this tool. Not yet today

My colleagues and I are helping to establish a framework that transforms this information into a format that can be used by the community, so municipalities use sewer monitoring to make rigorous decisions that affect people’s lives and economics. Helps to defeat. There is also a project to investigate the persistence of this infectious virus. Wastewater..

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