France has declared a significant rise in coronavirus cases – as researchers have said traces of COVID-19 are once again being found in Paris’ sewage system.
The country’s health ministry has reported more than 1,000 new cases per day, after a series of localised flare-ups prompted officials to make mask-wearing compulsory in enclosed public spaces.
Meanwhile, researchers say some locations in Paris that had been testing negative for traces of the virus in their wastewater have been testing positive since the end of June.
Image: A laboratory technician handles samples of waste water in Ivry-sur-Seine
The virus traces had initially been detected at the beginning of the outbreak but vanished when France went into lockdown.
Early studies by scientists across the globe suggest that sampling sewage for signs of coronavirus could help estimate the number of infections in a geographic area without having to test every person, and it could act as an early indicator before people are even diagnosed or sent to hospital.
Parisian researchers suggested in April that sampling wastewater in the city for a month reflected the rising and falling number of infections there.
Infection rates in France had appeared to be slowing.
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Laurent Moulin, who heads the research laboratory run by public water utility company Eau de Paris, insists the new findings on their own did not mean the virus is resurging.
But he said it could be used in conjunction with other data to detect early warning signs of the virus spreading, even before people become sick enough to seek medical help.
“We had the lockdown, which reduced the number of sick people, and then a little while later we saw a reduction of the concentration of [COVID-19] in the wastewater,” Mr Moulin said.
“What are we seeing since the end of June? We’ve seen some locations that were negative [for virus traces] and are becoming positive,” he said.
To collect the samples, workers at a sewage plant in Noisy-le-Grand have been filling plastic bottles with wastewater and putting them in a cool box.
These are then taken to the laboratory, where they are analysed by researchers in biohazard suits and masks.
The researchers test for coronavirus genomes – fragments of the virus’ genetic material which are not infectious and can be emitted by people who have no symptoms.
The evidence gathered by the laboratory will be used along with other data to track the progression of the virus.Scientists in the UK, led by the UK Centre for Ecology & Hydrology, are also conducting a similar study of wastewater.
Source : Sky News