The coronavirus was already present in two large cities in northern Italy in December, over two months before the first case was detected, a national health institute study of waste water has found.
Italian scientists say sewage water from two cities contained coronavirus traces in December, long before the country’s first confirmed cases.
The National Institute of Health (ISS) said water from Milan and Turin showed genetic virus traces on 18 December, BBC reported.
It adds to evidence from other countries that the virus may have been circulating much earlier than thought.
Chinese officials confirmed the first cases at the end of December. Italy’s first case was in mid-February.
In May French scientists said tests on samples showed a patient treated for suspected pneumonia near Paris on 27 December actually had the coronavirus.
Meanwhile in Spain a study found virus traces in waste water collected in mid-January in Barcelona, some 40 days before the first local case was discovered.
In their study, ISS scientists examined 40 sewage samples collected from wastewater treatment plants in northern Italy between last October and February.
Samples from October and November came back negative, showing that the virus had not yet arrived, ISS water quality expert Giuseppina La Rosa said. Waste water from Bologna began showing traces of the virus in January.
Italy was the first European country to be hit by the virus and the first in the world to impose a nationwide lockdown. The first known case, other than a couple of visiting Chinese tourists, was a patient in the town of Codogno in the Lombardy region.
Nearly 35,000 people have died with Covid-19 in Italy, a tally from Johns Hopkins University shows.