Within just a few months of it emerging, the novel coronavirus has managed to unleash havoc across the world, not only causing illness and death, but ravaging economies globally. One of the biggest challenges that health officials are faced with is testing for the virus on a scale sufficiently broad enough to detect and isolate infections to curb the spread of outbreaks throughout communities.

Wastewater-based epidemiology (WBE) is an innovative new approach for monitoring harmful pathogens and hazardous chemicals in sewage, an approach which also holds great promise for identifying the extent of Covid-19 infections both locally and on a broader scale. Analyzing wastewater samples allows officials to monitor disease outbreaks, drug-resistant bacteria and viruses, as well as extent of drug usage or indicators of health issues such as diabetes, for example.

A study conducted by researchers from Arizona State University, which was recently published in the journal Science of the Total Environment, assesses the merits of using WBE for tracking Covid-19 in wastewater, and highlights the advantages this method offers over conventional method used to test, screen and monitor diseases.

"Our results show that exclusive reliance on testing of individuals is too slow, cost-prohibitive and in most places, impractical, given our current testing capacity," said study co-author, Rolf Halden, Director of the Biodesign Center for Health Engineering and a professor in the Fulton School of Sustainable Engineering and the Built Environment at ASU. "However, when preceded by population-wide screening of wastewater, the task becomes less daunting and more manageable."

Wastewater-based epidemiology, which uses DNA sequencing to identify pathogens, not only offers the potential to speed up coronavirus screening in highly populated developed countries such as the US, but could also provide a valuable tool for collecting health data from populations living in poorer regions, who are likely to be most vulnerable to Covid-19 outbreaks due to the lack of screening and testing facilities.

Having a clearer picture of the level of Covid-19 infections in communities allows authorities to take the necessary steps to reduce transmission and related fatalities. This can include measures such as redirecting resources to hot spots, and implementing localized lock downs and social distancing restrictions, while lifting these in regions where the virus is less prominent, thereby minimizing the social and economic impact of these restrictions.

Halden together with his colleagues has created a non-profit organization, OneWaterOneHealth, which aims to provide Covid-19 testing to regions who are unable to afford it.

According to Halden, if this approach was rolled out in the US, it would allow approximately of 70% of the population to be screened for Covid-19 by monitoring sewage at 15,014 wastewater treatment plants across the country at an estimated cost of $225,000 for the chemical reagents required in the process.

This approach could be used to identify local or global Covid-19 hot spots, and then refined further by using standard clinical methods for more targeted testing of individuals living within these hot spots.

According to the study:

"Each person infected with SARS-CoV-2 will excrete millions if not billions of viral genomes into wastewater per day."

Wastewater screening could therefore provide a reliable and cost-effective method of assessing the levels of infection within communities. The other side of the coin is that this could also pose a potential health risk if contaminated wastewater should escape into the environment. While wastewater treatment plants may have measures in place to ensure effluent that is discharged into the environment meets the required health standards, private septic systems are not monitored and therefore do not have the same precautionary measures in place to prevent contamination of freshwater systems and potentially drinking water sources.

Journal Reference

Olga E. Hart & Rolf U. Halden. Computational analysis of SARS-CoV-2/COVID-19 surveillance by wastewater-based epidemiology locally and globally: Feasibility, economy, opportunities and challenges. Science of The Total Environment, Volume 730, 15 August 2020, 138875