Kerala-born Sudhi Payyappat is leading a team of 20 in examining dozens of sewage samples collected from wastewater treatment plants across New South Wales (NSW) in Australia testing for COVID-19 and trying to stop its spread in the community.

He and his team have helped millions across Australia in steering clear of the coronavirus, all by looking closely at human faeces.

In March last year, Payyappat, a microbiologist who is now settled in Sydney, adopted a methodology for testing waste-water to locate fragments of SARS-CoV-2 and thus detect hidden cases within the community.

His methodology is found on the premise that a person infected with coronavirus will start ‘shedding’ the virus within three-four days through his faeces.

“I was really surprised by the sensitivity of this method. If one person is shedding the virus in a catchment of a 20,000-30,000 population, we will be able to pick it (virus) up in the treatment plant. It has a huge economic potential as it is equivalent to monitoring that many people. It has helped in containing the spread of the infection,” 50-year-old Payyappat was quoted by the media.

Payyappat, who works as a technical specialist with Sydney Water, a government-owned corporation, for the past 20 years, said that after they detect a sample, they inform the department of health, which puts out an alert through the media that the remnants of SARS-CoV-2 were found in a particular area.

“The department asks people in that catchment to go and test for COVID even if they have mild symptoms,” he said.

According to the ABC News, about 80 samples a week from Sydney’s 25 wastewater treatment plants were brought into the lab, as well as samples from the 40 wastewater treatment centres across regional NSW.

The biggest advantage of the testing of sewage, he stressed, is that authorities can tell if someone is infected in the community even before they start showing symptoms.

He said that “once you get the virus, you may show symptoms only from six or seven days onwards, or you may be an asymptomatic carrier. But you start shedding the virus within three days.”

This helps them time to arrest the spread of infection. Another advantage is that if the infection is already present in the community, through sewage testing, they can see if the numbers are increasing, decreasing or stabilizing.

With the success of Payyapat’s model in Sydney, the testing regime has been expanded to other states of Australia. He’s currently working on devising a monitoring programme for COVID waste-water surveillance for Thailand, reports said.