Covid traces in the waste waters of Milan and Turin as early as December


AGI – In the waste waters of Milan and Turin there were already traces of the SARS-CoV-2 virus in December 2019. This was discovered by a study being published by the Istituto Superiore di Sanità carried out through the analysis of waste water collected in times before the onset of the coronavirus in Italy. The samples taken in the purifiers of urban centers in northern Italy have been used as a “spy” of the circulation of the virus in the population.

“Since 2007 with my group we carry out research in environmental virology and collect and analyze samples of waste water taken at the entrance of purification plants”, explains Giuseppina La Rosa of the Department of Water Quality and Health of the Department of Environment and Health of the Istituto Superiore di Sanità, 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 wastewater samples collected from October 2019 to February 2020, and 24 control samples for which the sampling date (September 2018 – June 2019) allowed to safely exclude the presence of the virus The results, confirmed in the two different laboratories with two different methods, showed the presence of SARS-Cov-2 RNA in the samples taken in Milan and Turin on 12/18/2019 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, gave negative results “.

This research may help to understand the beginning of the virus’s circulation in Italy and provides information consistent with other results obtained from the retrospective analysis on samples of hospitalized patients in France, which identified a SARS-CoV-2 positive in a respiratory sample , therefore clinical, dating back to the end of December 2019, and to a recent Spanish work that found SARS-CoV-2 RNA in waste water samples collected in mid-January in Barcelona, ​​about 40 days before the notification of the first case native “.

“Our results – underlines Luca Lucentini, director of the Quality of Water and Health Department – confirm the consolidated international evidence on the strategic function of monitoring the virus in samples taken regularly in the sewers and at the entrance to the treatment plants, as a tool able to detect and monitor the circulation of the virus in the various territories early, supporting the fundamental information of integrated, microbiological and epidemiological surveillance. the finding 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 in the area can prove invaluable in controlling the epidemic. Through the activity carried out in our laboratories, an environmental surveillance network is developing which can already count on the availability and reliability of health and environmental structures of excellence at a regional level and on the fundamental contribution and collaboration of water managers who can even more contribute to a widespread and timely development “.

“Moving from research to surveillance – continues Lucentini – it will be essential to arrive at a standardization of methods and sampling since the positivity of the samples is affected by many variables such as, for example, the sampling period, any meteorological precipitations, the emission of waste from industrial activities which can affect the results of activities to date conducted by different groups. We work to give the country a surveillance network together with Arpa and Ispra “.

“In this sense – concludes Lucia Bonadonna, director of the Department of Environment and Health of the ISS – 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 already 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 on the whole national territory in the potentially most critical periods of next autumn “.

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