Scientists in Italy have found traces of coronavirus in wastewater collected from Milan and Turin in December 2019.
It suggests COVID-19 was already circulating in Northern Italy before China reported the first cases on December 31.
The Italian National Institute of Health looked at 40 sewage samples collected from wastewater treatment plants in northern Italy between October 2019 and February 2020.
An analysis released last week said samples taken in Milan and Turin on December 18 showed the presence of the SARS-Cov-2 virus.
The first confirmed case of coronavirus in Italy came on January 31.
‘This research may help us understand the beginning of virus circulation in Italy,’ Giuseppina La Rosa, an expert in environmental wastewater at the Italian National Institute of Health who co-led the research, said in a statement detailing the findings.
Scientists in Italy have found traces of coronavirus in wastewater collected from Milan and Turin in December 2019
Small studies conducted by scientific teams in the Netherlands, France, Australia and elsewhere have found signs that the virus that causes COVID-19 can be detected in sewage, and many countries are beginning to use wastewater sampling to track the spread of the disease.
La Rosa said the detection of traces of the virus before the end of 2019 was consistent with evidence emerging in other countries that COVID-19 may have been circulating before China reported the first cases of a new disease on December 31.
A study in May by French scientists found that a man was infected with COVID-19 as early as December 27, nearly a month before France confirmed its first cases.
La Rosa said the presence of the virus in the Italian waste samples did not ‘automatically imply that the main transmission chains that led to the development of the epidemic in our country originated from these very first cases’.
Samples positive for traces of the virus that causes COVID-19 were also found in sewage from Bologna, Milan and Turin in January and February 2020.
Samples taken in October and November 2019 tested negative.
The institute said it plans to launch a pilot study in July to monitor wastewater at sites identified in tourist resorts.
It comes after previous research by University College London’s Genetics Institute suggested coronavirus may have emerged as early as October last year.
A genetic study of samples from more than 7,500 people infected with COVID-19 indicated that the new coronavirus spread quickly around the world after it emerged in China sometime between October and December last year.
Researchers at University College London’s Genetics Institute found almost 200 recurrent genetic mutations of the new coronavirus – SARS-CoV-2 – which the UCL researchers said showed how it is adapting to its human hosts as it spreads.
‘Phylogenetic estimates support that the COVID-2 pandemic started sometime around October 6, 2019 to December 11, 2019, which corresponds to the time of the host jump into humans,’ the research team, co-led by Francois Balloux, wrote in a study published in the journal Infection, Genetics and Evolution.
Balloux said the analysis also found that the virus was and is mutating, as normally happens with viruses, and that a large proportion of the global genetic diversity of the virus causing COVID-19 was found in all of the hardest-hit countries.