Sewage tests could provide early indicator of COVID-19 outbreaks

The United Kingdom government is exploring if it is possible to detect novel coronavirus in municipal wastewater, which could help health officials predict where new outbreaks are set to occur.

On Monday, Prime Minister Boris Johnson said that if the virus can be detected in the "water supply" the government could then take steps to deal with "local flareups". A Downing Street spokesperson later clarified that the government is looking at testing sewage.

"Yes, that specifically is a reference to sewage or wastewater, as it is more politely described," the spokesperson said. "Some studies have been carried out overseas on this and I think it is something we are looking at as a possible way of seeing if you could track the rate of infections locally."

Wastewater-based epidemiology has flourished as a field of study in the last two decades. Researchers have developed various techniques to track levels of illicit drug use, pharmaceuticals, and other chemical compounds in populations by testing wastewater as it arrives at treatment plants.

Scientists have also used similar methods to test sewage in order to monitor human health and potential outbreaks of disease. In the UK, Yang Zhugen, a lecturer in sensor technology at the Cranfield Water Science Institute, is at the forefront of this research.

Yang says there are devices that can test wastewater for parasites including malaria, harmful bacteria including E.Coli and salmonella, and viruses including zika, human papillomavirus, and HIV.

In collaboration with researchers from the Chinese Academy of Sciences, Yang has started looking at developing a testing kit that could detect novel coronavirus in sewage.

"If COVID-19 can be monitored in a community at an early stage through wastewater-based epidemiology, effective intervention can be taken as early as possible to restrict the movements of that local population, working to minimize the pathogen spread and threat to public health," said Yang.

Yang said studies have shown that live novel coronavirus can be isolated from the feces and urine of infected people and the virus can typically survive for several days in an appropriate environment after exiting the human body.

In a study published in the journal Environmental Science and Technology, Yang and his colleagues propose an inexpensive paper-based device could be used to test novel coronavirus at wastewater treatment sites.

Yang says that currently, the most direct method for the detection of COVID-19 is a nucleic acid-based polymerase chain reaction assay. He says this method is not conducive to rapid detection in the field, as it requires complicated sample handling in the laboratory, skilled personnel, and a long period of data processing and analysis.

Instead, a comparatively simple paper device costing less than 1 pound ($1.24) can filter nucleic acids of pathogens from wastewater samples, then a biochemical reaction with reagents detects whether the nucleic acid of novel coronavirus infection is present. Results are visible to the naked eye－a green circle indicates a positive result and a blue circle is negative.

"We have already developed a paper device for testing genetic material in wastewater for proof-of-concept, and this provides clear potential to test for infection with adaption," Yang said. "This device is cheap and will be easy to use for non-experts after further improvement. We foresee that the device will be able to offer a complete and immediate picture of population health once this sensor can be deployed in the near future."

Scientists in the Netherlands say they have already been able to isolate novel coronavirus in sewage systems. Microbiologists at the KWR Water Research Institute in Nieuwegein detected the virus at a wastewater plant in Amersfoort, near Utrecht, on March 5. The sample was collected weeks before the first case of COVID-19 was confirmed in Utrecht, suggesting that wastewater-based epidemiology can be used as an early indicator for the presence of novel coronavirus in a population.

Researchers at Bangor University have been testing for novel coronavirus in wastewater treatment sites across Wales, and early analysis shows that concentrations of the virus are in line with infection rates in the tested areas.

Scientists at Newcastle University in the UK and the University of Santiago de Compostela in Spain are monitoring sewage from across networks in North East England and Spain.