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Waste water tests can identify virus weeks before symptoms


Testing untreated sewage can detect COVID-19 in communities weeks before people display symptoms.

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That’s the conclusion of new research by the CSIRO and the University of Queensland and could lead to an early detection system as economies re-open and people become more mobile.

The researchers analysed Brisbane wastewater samples from February and March, tracking genetic fragments of the COVID-19 virus flushed into the wastewater system through infected people’s faeces.

They found the samples were able to detect the genetic fingerprint of the virus up to three weeks before the first COVID-19 cases were publicly reported.

The discovery could allow authorities to target specific areas for public health interventions and avoid full lock-downs of larger regions.

CSIRO CEO Dr Larry Marshall said wastewater testing could help open up borders to drive Australia’s recovery and reduce future disruption.

“Australians want to do the right thing, but this solution from science detects the disease before people feel the symptoms, so we can out-think and outmanoeuvre this insidious virus,” Marshall said.

CSIRO study lead author Dr Warish Ahmed said wastewater testing was gaining international recognition as an important tool in the pandemic response.

The analysis involves tracking genetic fragments of the COVID-19 virus which are flushed into the wastewater system through infected people’s faeces.

Only two other studies have been published globally confirming the virus detection between one and four weeks prior to people showing clinical symptoms.

Professor Trevor Drew, from CSIRO’s Australian Centre for Disease Preparedness, confirmed people can become infected and spread – or “shed” – SARS-CoV-2, the virus that causes COVID-19, before showing any symptoms.

“Evidence has shown that this virus can infect people and replicate itself for some time before they start showing any symptoms, and some people are entirely asymptomatic but still shed the virus,” he said.

The study also suggested if sampling was frequent and widespread, testing could detect the virus before people felt sick, as their bodies start shedding fragments of the virus into the wastewater system through their faeces before they know they’re infected.

The researchers have been helping Queensland Health with a wastewater surveillance program since July.

They have tested sewage for traces of the COVID-19 virus in dozens of locations across Queensland.

The findings were published in the journal Science of the Total Environment.

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