Testing Perth wastewater for virus could start in October

As early as next month PathWest could start testing wastewater from Alkimos and Beenyup wastewater treatment plants for the virus which causes Covid-19. File picture

OCTOBER is provisionally when the Department of Health expects PathWest to start testing metropolitan wastewater including samples from the Alkimos and Beenyup wastewater treatment plants for SARS-CoV-2, the virus which causes Covid-19.

Earlier this month Health Minister Roger Cook said preliminary sampling had been happening in the metropolitan area.

Last week a Department of Health spokeswoman confirmed the Water Corporation had started collecting samples from the Alkimos and Beenyup wastewater treatment plants in April.

The spokeswoman said the results of the testing would be released to the public.

“The timing and method of releasing results is yet to be determined,’’ she said.

In Testing wastewater could prevent local Covid-19 outbreaks, May 6 the Water Corporation said wastewater from households and businesses within the City of Wanneroo’s boundaries was treated at both the Alkimos wastewater treatment plant, which treats wastewater from about 80,000 people and the Beenyup wastewater treatment plant in Craigie, which treats wastewater from about 660,000 people.

The Department of Health spokeswoman said there was no plan to sample the wastewater in Ledge Point, Lancelin and Seabird but whether wastewater was to be sampled in other regional towns was yet to be determined.

She said the lack of deep sewerage in many areas of WA such as old Yanchep and much of the Shire of Gingin where homes have septic tanks would not put some limitation on using data from wastewater testing to help inform WA’s Covid-19 restrictions.

She also said the lack of deep sewerage in many areas would not put some limitation on using data from wastewater testing to help inform any decisions about locking parts of WA down if Covid-19 ever starts to spread in the community.

How sewage testing helps contain Covid-19 describes the testing of wastewater as an early warning tool for detecting the spread of Covid-19.

According to the CSIRO sewage analysis can detect SARS-CoV-2, the virus causing Ccovid-19, in a population days before positive cases or clusters show up.

CSIRO researcher Paul Bertsch said it was now known that people start shedding the virus in their faeces about two to three days after first being infected with SARS-CoV-2 – well before they show symptoms of Covid-19, if they notice any symptoms at all.

“After it’s flushed into the sewerage system, the virus gradually disintegrates, leaving behind fragments of its unique RNA signature.’’

Scientists use a process called reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to isolate and confirm the virus’s fingerprint over any other genetic material present in the sample.

He said as some experts say it could be a long time before there is a vaccine.

“So a national wastewater surveillance program or network could help Australian authorities detect and contain emerging Covid-19 clusters faster and more cost-effectively,’’ he said.

“The technique can also be used to detect the virus in smaller populations, like aged-care facilities, schools and prisons, where Covid-19 prevention is particularly critical.’’

On September 18 Mr Cook said the collaboration on sewage surveillance of SARS-CoV-2 (ColoSSoS) project would track and monitor for traces of the virus in WA’s sewerage network.

The project will aim to answer questions such as what are the best sites to test, the testing frequency and interpreting the information.

Individual testing of people at Covid clinics and other collection facilities remains the mainstay of detection for Covid-19 in WA.