In a significant development, Indian scientists recently discovered the genetic material of SARS-CoV-2 virus in wastewater. The discovery has paved the way for using wastewater-based epidemiology (WBE) for real-time surveillance of Covid-19 in the country, India Today reported.
The study, led by scientists in IIT-Gandhinagar, found that increased “gene copies” of the virus in Ahmedabad’s wastewater matched the incidence of the disease in the city. With this, India “joins the ranks of a handful of countries doing a WBE on Covid-19,” Andrew Singer, an environmental microbiologist at the UK Centre for Ecology & Hydrology, posted on Twitter.
WBE is an effective approach to monitor the spread of the virus in a particular catchment by monitoring viral load in wastewater.
Recent studies have also proved the presence of the novel coronavirus (SARS-CoV-2) in the faeces of infected individuals. Genetic material (RNA) from the virus has been found in sewage entering treatment plants.
Researchers saiduntreated wastewater may provide deep insights into the percentage of people infected in a particular catchment area.
According to the India Today report, all the three SARS-CoV-2 genes -- ORF1ab, N and S -- were present in the wastewater flowing into the treatment plant, said the researchers, who have submitted their study for publication in the international journal Science of the Total Environment.
They noted that no gene was spotted in the effluent leaving the plant after treatment.
The scientists said the gene copy loading - the quantity of genetic material of the virus - increased 10-fold between May 8-May 27.
This corresponded broadly with the trajectory of the incidence of the disease. The number of active Covid-19 patients in Ahmedabad city was two times higher on May 27 than on May 8, they said.
According to the scientists, WBE was an effective tool during outbreaks of other viruses such as poliovirus and hepatitis A.
The Ahmedabad study aims at assisting the concerned authorities and policymakers to formulate or upgrade Covid-19 surveillance to get a clear picture of the phase of the pandemic, the researchers added.
Kumar cited reports to say that the same study had pointed out the presence of the virus in Italy in late December, way before the first confirmed case was reported in the country.
Advanced surveillance system
“Developing an advanced surveillance system for environmental samples using biotechnological approaches is the need of the hour. This can help us track real-time situations not only for the current pandemic but also for seasonal epidemics,” Madhvi Joshi, joint director of GBRC and one of the authors of the paper, told PTI.
According to the researchers, the number of gene copies found was similar to the tally of Australia, China and Turkey, and lower than that of the US, France and Spain.
Prosun Bhattacharya of Sweden’s KTH Royal Institute of Technology noted that WBE can be very impactful in the war against Covid-19 with the right information about the catchment and number of people residing in the vicinity.
He added that the research by Kumar and his colleagues has put India on the world map pertaining to WBE surveillance.
According to the European and North American data estimates, each Covid-19 infected person will excrete millions if not billions of viral genomes into wastewater per day.
This translates to between 0.15 and 141.5 million viral genomes per litre of wastewater generated, the researchers said.
Using reverse transcription PCR (RT-qPCR) -- a laboratory technique of molecular biology -- researchers should be able to detect the novel coronavirus with high sensitivity, Kumar said.
“The findings reported by Kumar and colleagues demonstrate the successful detection of SARS-CoV-2 in wastewater -- a highly valuable contribution to global SARS-CoV-2 surveillance research efforts,” Kyle Bibby, associate professor and leader of Global Collaboration on WBE, the University of Notre Dame in the US, told PTI.
“I would like to congratulate India as one of the elite nations in world-wide efforts in detecting and quantifying SARS-CoV-2 genetic materials in their sewage samples. Kumar and his colleagues showed the capabilities of wastewater-based epidemiology (WBE) in India, the second most populated nation with rapidly growing numbers of Covid-19 confirmed cases,” said Keisuke Kuroda, associate professor in Environmental and Civil Engineering at Toyama Prefectural University, Japan.
“This report will surely facilitate a nationwide initiative for detecting the early warning signals of Covid-19 outbreaks in various communities,” Kuroda told PTI.
Ryo Honda of Japan’s Kanazawa University, who is leading a task force on wastewater surveillance in Japan, said the study is an important step for WBE of Covid-19 in India.