Brazilian researchers recall how they find coronavirus in waste water

Brazil: Researchers at the Federal University of Santa Catarina (UFSC) in Brazil, who had detected the presence of the novel coronavirus traces in the waste water samples collected from last November in the country, recalled the process of finding and offered the plan for the next step.

Their sewage water study in early July showed that sewage water samples from November 27 last year in Florianopolis, the capital and second largest city of the state of Santa Catarina, was found to contain COVID-19 traces. "Particles of the new coronavirus, SARS-CoV-2, were found in two samples of Florianopolis sewage collected on November 27, 2019," the research group said in a report published on the university's official website.

The finding is three months earlier than the first reported case in Brazil at the end of February, which arouses global concern.

The research team collected urban sewage samples in Florianopolis in six independent sampling events between October 2019 and March 2020.

"Results came back positive for SARS-CoV-2 for the first time for a sample from November 27. And tested samples from December, February and March all came back positive. Our study shows that novel coronavirus was already present in Brazil waste water in November 2019," said Gislaine Fongaro, co-author of the study.

At first, the researchers were skeptical of the result, so they conducted a second test with virus markers in different labs, repeated all data and tracked the virus genome. The test results are the same. Then, the research group also sequenced the full genome of the virus samples. The group leader, Patricia Stoco, a geneticist, said that they found the gene sequence of new coronavirus in samples based on the first phase of full genome sequencing.

Now, researchers have begun to look into older clinical samples taken from patients with similar symptoms of COVID-19, in order to further prove that the virus had existed last year. "If the sequencing results prove the virus is the new coronavirus, we can confirm COVID-19 clinical cases and novel coronavirus in sewage water were present earlier than the official record, which had circulated very early," she said.

Apart from Brazil, coronavirus had been scientifically identified in sewages in Spain and Italy collected on March 12 and December 18 respectively before the first confirmed cases were reported in Europe earlier this year.