Coronavirus has been found in sewage water in the Netherlands and is likely to have got there from the faeces of patients with Covid-19, according to a new report.
Dutch researchers said the Sars-CoV-2 coronavirus was present in samples taken from a sewage treatment plants at Amsterdam Schiphol Airport and the village of Kaatsheuvel, which treats waste water from the town where the country's first Covid-19 patient lives.
Their report, published by the Dutch National Institute for Public Health and the Environment, suggests monitoring sewage water is a good way of checking whether viruses such as SARS-COV-2 are present in the population.
It has previously found traces of the norovirus, antibiotic-resistant bacteria and measles in waste water using the same technique.
A small percentage of infected people, particularly those who experience diarrhoea as a symptom, excrete virus genomes into sewers.
"Using molecular methods, the virus that causes COVID-19 was detected in wastewater at Amsterdam Schiphol Airport, in Tilburg and at the wastewater treatment plant in Kaatsheuvel," the report said.
"This plant treats the wastewater from Loon op Zand, the town where the first reported Covid-19 patient in the Netherlands lives."
To get their data, researchers collected weekly samples from the sewage treatment plants at Schiphol Airport, Tilburg and Kaatsheuvel from February 17 onwards.
"During the first two weeks, the virus that causes Covid-19 was not detected," they wrote.
"However, the genetic material from the virus was detected in the airport wastewater samples taken on 2, 9 and 16 March. The first sample containing the virus was taken four days after the first person in the Netherlands tested positive for Covid-19 on February 27.
"Genetic material from the virus was detected in wastewater samples taken from the wastewater treatment plant in Tilburg on 3, 10 and 17 March. Again, the first sample containing the virus was taken within the first week after the first confirmed cases occurred.
"Of the wastewater samples taken from the wastewater treatment plant in Kaatsheuvel on 3 and 18 March, only the sample taken on 18 March contained genetic material from the virus that causes COVID-19."
Dutch authorities said sewage treatment workers were already required to wear personal protective gear that protects them from pathogens, including Sars-CoV-2.
The report was met with scepticism by some experts, who said there was no evidence the virus traces in the Dutch sewage system posed a direct threat to humans.
"We repeat to the gazillions time (sic): Detection of RNA is not the same as detection of infectious virus!!" Bjorn Meyer, a virologist at the Pasteur Institute in Paris, tweeted.
"Yes, patients excrete #SARSCoV2 genomes through their faeces, shown now many times over. This doesn't mean they easily excrete infectious virus, never mind it surviving (the) environment!"