Coronavirus was in Italy in December, waste water study finds
- Researchers discovered genetic traces of the virus in samples of waste water collected in Milan and Turin at the end of last year
- Italy’s first known native case was discovered mid-February
Researchers discovered genetic traces of Sars-Cov-2 – as the virus is officially known – in samples of waste water collected in Milan and Turin at the end of last year, and Bologna in January, the ISS institute said in a statement on Friday.
The results “help to understand the start of the circulation of the virus in Italy,” the ISS said.
They also “confirm the by-now consolidated international evidence” as to the strategic function of sewer samples as an early detection tool, it added.
Coronavirus: Decoding Covid-19
On February 21, the government designated Codogno a so-called red zone and ordered it closed, followed by nine other towns across Lombardy and Veneto. By early March it had extended the shutdown across the country.
Italy has recorded over 34,500 deaths.
ISS water quality expert Giuseppina La Rosa and her team examined 40 waste water samples from October 2019 to February 2020.
The results, confirmed in two different laboratories by two different methods, showed the presence of SARS-Cov-2 in samples taken in Milan and Turin on December 18, 2019 and in Bologna on January 29, 2020.
Samples from October and November 2019 were negative, showing the virus had yet to arrive, La Rosa said.
Given the large number of coronavirus cases that have little or no symptoms, waste water testing could signal the presence of the virus even before the first cases are clinically confirmed in areas untouched by the epidemic or where it has ebbed.
The ISS said it had urged the health ministry to coordinate the collection of samples regularly in sewers and at the entrance to purification plants “as a tool to detect and monitor the circulation of the virus in different territories at an early stage”.
It is launching a pilot study on priority sites identified in tourist resorts in July, and expected to set-up a nationwide surveillance network of waste water by the autumn.