CS N ° 39/2020 - ISS study on wastewater, in Milan and Turin Sars-Cov-2 already present in December

ISS, 18 June 2020 - There were already traces of the SARS-CoV-2 virus in the wastewater of Milan and Turin in December 2019. A study is soon to be published by the Italian National Institute of Health (ISS) carried out through the analysis of wastewater collected in times prior to the occurrence of COVID-19 in Italy. The samples taken in the purifiers of urban centers in northern Italy were used as a "spy" of the circulation of the virus in the population.

"Since 2007 with my group* we have been carrying out research in environmental virology and collecting and analyzing wastewater samples taken at the entrance to sewage treatment plants," explains Giuseppina La Rosa of the Department of Water Quality and Health of the Department of Environment and Health of the Italian National Institute of Health, which conducted the study in collaboration with Elisabetta Suffredini of the Department of Food Safety, Nutrition and Veterinary Public Health. "The study,” continues La Rosa, “examined 40 samples of wastewater collected from October 2019 to February 2020, and 24 control samples for which the collection date (September 2018 - June 2019) allowed to safely exclude the presence of the virus. The results, confirmed in two different laboratories with two different methods, showed the presence of SARS-Cov-2 RNA in the samples taken in Milan and Turin on 18/12/2019 and in Bologna on 01/29/2020. In the same cities, positive samples were also found in the following months of January and February 2020, while the samples of October and November 2019, as well as all the control samples, were negative."

This research may help us understand when the virus began circulating in Italy and provides information consistent with other results obtained from a retrospective analysis of samples of hospitalized patients in France, which identified a SARS-CoV-2 positive in a respiratory sample, then clinical, dating back to the end of December 2019; and to a recent Spanish study that found SARS-CoV-2 RNA in wastewater samples collected in mid January in Barcelona, about 40 days before the notification of the first known case."

"Our results,” says Luca Lucentini, director of the Quality of Water and Health Department, “confirm the evidence now consolidated internationally on the utility of monitoring the virus in samples taken regularly in the sewers and at the entrance to treatment plants, as a tool to be able to identify and monitor early circulation of the virus in the various territories, supporting the fundamental information of integrated, microbiological and epidemiological surveillance. It should be noted that the discovery of the virus does not automatically imply that the main transmission chains that led to the development of the epidemic in our country originated from these first cases, but, in perspective, a surveillance network on the territory can prove invaluable in controlling the epidemic. Through the activities carried out in our laboratories, we are developing an environmental surveillance network that can count on the availability and reliability of health and environmental standards of excellence at the regional level, and on the contribution and collaboration of water managers who can contribute to its widespread and timely development."

"Moving from research to surveillance,” Lucentini goes on, “it will be essential to arrive at a standardization of methods and samplings since the positivity of the samples is affected by many variables such as, for example, the sampling period, meteorological precipitations, the emission of waste from industrial activities that can affect the results of activities conducted by different groups. We work to give the country a surveillance network together with Arpa (Regional Environmental Protection Agency) and ISPRA (Higher Institute for Environmental Protection and Research).

"In this sense,” concludes Lucia Bonadonna, director of the Department of Environment and Health of the Italian National Institute of Health, “we have presented a proposal for action to the Ministry of Health for the launch of a surveillance network on SARS-CoV-2 in wastewater, and as early as next July we will launch a pilot study on priority sites identified in tourist locations. Based on the results of the pilot study, we hope to be ready for surveillance throughout the country in the potentially most critical periods of next autumn."

* Marcello Iaconelli, Giusy Bonanno Ferraro, Pamela Mancini e Carolina Veneri