Sewage water could hold evidence of virus circulation

NEWDELHI: Testing sewage water could give clues about the circulation of Covid-19 in cities. Scientists in the Netherlands found the virus in sewage water even when the outbreak was still in its early stages in Dutch cities.

In another analysis, scientists suggested the use of paper-based devices to trace these pathogens early on.

In the Dutch study, published in pre-print service medRxiv, tests were conducted on sewage water samples three weeks before the first Covid-19 case in the Netherlands but no markers were found. When the test was conducted again a week after the outbreak, markers were found.

Scientists clarified there was no evidence yet that sewage is a transmission mode for the virus. Although SARS-CoV-2 has been detected in a significant proportion of stool samples in earlier studies, just two studies reported finding infectious virus from these samples. This indicates it doesn’t sustain in treated sewage water for long. “Sewage surveillance could also serve as early warning of the re-emergence of Covid-19 in cities, much like the sewage surveillance for poliovirus that has been used for this purpose,” authors from the KWR Water Research Institute in the Netherlands said in the study.

Another analysis published in the Environment Science and Technology journal by scientists from the School of Water, Energy and Environment, Cranfield University, and Chinese Academy of Sciences spoke on the paperbased devices.

Dr Zhugen Yang, lecturer at Cranfield Water Science Institute, said: “In the case of asymptomatic infections in the community or when people are not sure whether they are infected or not, real time community sewage detection through paper analytical devices could determine whether there are Covid-19 carriers in an area.”

“Sewage surveillance has been done for polio and non-polio viruses in the past. But I think that would be a post -pandemic response in India. We need testing kits to be available right now. That’s a priority,” said Dr Shobha Broor, former head of microbiology at AIIMS, Delhi.