A new study has shown the coronavirus was present in Milan and Turin's sewage systems as early as December, two months before the first Covid-19 cases were detected in Italy.
"Traces of SARS-Cov-2 have been found in samples of waste water taken in Milan and Turin on Dec. 18 and in Bologna on Jan. 29," said Giuseppina La Rosa, who led the research for a coming study from the country's ISS National Health Institute, reports Bloomberg.
"More traces were detected in other test samples through January and February."
The report is part of a regular round of testing on environmental virology that has been carried out since 2007 by the ISS's environment and health department.
Overall, 40 samples were analyzed from October 2019 to February 2020 with an additional 24 from September 2018 through June 2019 used as controls.
Hospital tests in the coastal region of Liguria have also indicated the likelihood that the virus was present in the country at the end of last year, Italian newspapers have reported. Italy's earliest reported domestic virus cases have been linked to a man who sought treatment in mid-February of this year, though some people arriving from abroad had been diagnosed with the disease earlier in the winter.
The new ISS study "may contribute to shedding light on the first phase of the virus's circulation in Italy," La Rosa said.
The results are consistent with similar tests carried out on waste water in Barcelona and with clinical tests on patients hospitalized in France, which showed biological traces of the virus as early as last December.