Australian researchers have found SARS-CoV-2 virus in wastewater samples from long haul flights arriving from outside the country, demonstrating that they can detect it even before passengers show symptoms.
The CSIRO and University of Queensland scientists worked with Qantas to show that wastewater surveillance can provide valuable data for public health agencies.
CSIRO lead author Dr Warish Ahmed said as global travel returns, testing wastewater of incoming flights could screen incoming passengers for COVID at points of entry.
“It provides an extra layer of data, if there is a possible lag in viral detection in deep nasal and throat samples and if passengers are yet to show symptoms,” Dr Ahmed said.
“The rapid on-site surveillance of wastewater at points of entry may be effective for detecting and monitoring other infectious agents that are circulating globally and provide alert to future pandemics.”
Co-author Professor Jochen Mueller from UQ’s Queensland Alliance for Environmental Health Sciences said wastewater testing could be a useful extra tool.
“The paper recommends that wastewater surveillance be used as part of an efficient clinical surveillance and quarantine system – providing multiple lines of evidence of the COVID infection status of passengers during international travel,” Professor Mueller said.
The study, published in Environment International, analysed wastewater samples from 37 Australian Government repatriation flights from COVID hotspots including India, France, UK, South Africa, Canada and Germany between December 2020 and March 2021.
The research found SARS-CoV-2 in wastewater samples from 24 of the 37 repatriation flights (65%) despite all passengers (except children under age five) having tested negative to the virus 48 hours before boarding. Virus is shed in the faeces of infected people about two to five days before showing symptoms.
Traces of SARS-CoV-2 can also be detected in wastewater from previously infected people who still shed the coronavirus, but are no longer infectious – although typically a weaker signal.
During 14 days of the passengers’ mandatory quarantine upon arrival in Australia, clinical tests identified only 112 COVID cases among the 6570 passengers (1.7%).
Monitoring of wastewater has a number of applications. Through its wastewater monitoring programme, the Durban University of Technology found that the recent unrest in South Africa was a superspreader event that drove up cases in KwaZulu-Natal.
Source: University of Queensland
