First detection of SARS-COV-2 In untreated wastewaters in Italy.

The first detection of SARS-COV-2 In untreated wastewaters in Italy. Jefferson T, Heneghan C.

Published on June 30, 2020

Reference La Rosa G, Iaconelli M, Mancini P, Bonanno Ferraro G, Veneri C, Bonadonna L, et al. FIRST DETECTION OF SARS-COV-2 IN UNTREATED WASTEWATERS IN ITALY.  medRxiv. 2020:2020.04.25.20079830. 2020
Study type
Country Italy
Setting Wastewaters
Funding Details Non reported
Transmission mode Orofecal
Exposures Sewage

Bottom Line

SARS-CoV-2 RNA fragments have been identified in sewage in Italy however the WHO protocol for sewage treatment of enveloped viruses after appropriate modifications is viable. The authors report a novel RT PCR test for screening of waters.

Evidence Summary

Thirty SARS-CoV-2 RNA detection occurred in volumes of 250 mL of wastewaters collected in both areas at high (Milan) and low (Rome) epidemic circulation, according to clinical data. 

Six out of 12 samples were positive. One of the positive results was obtained in a Milan wastewater sample collected three days after the first notified Italian case of autochthonous SARS-CoV-2 at Codogno. A second positive sample was taken on the 28th of February in Milan when COVID-19 cases were only 29.

The study shows that wastewater-based epidemiology has the potential to be applied to SARS-CoV-2 as a sensitive tool to study population trends in virus circulation.  Environmental screening may be a very sensitive tool to gauge viral presence before clinical symptoms develop. 

What did they do?

This is an environmental surveillance study based on twelve influent sewage samples, collected between February and 26 April 2020 from wastewater treatment plants in Milan and Rome. These were tested adapting the standard WHO procedure for Poliovirus surveillance by molecular analysis with three nested protocols, including a newly designed SARS-CoV-2 specific primer set.

Study reliability

The authors did not sample before the 23rd of February so we do not know whether SARS-CoV-2 was present before the 21st of February (the date the index case report to Codogno Hospital A&E)

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes N/A Yes N/A N/A

What else should I consider?

The study was limited in time and number of plants. No comment is made on the viability of retrieved samples, although the first isolate is described as weak.

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Tom Jefferson

Tom Jefferson, epidemiologist.