Have you ever wondered what goes on behind the scenes in an airplane toilet? Well in uncertain times, the Commonwealth Scientific and Industrial Research Organization (CSIRO) is checking poop for COVID.

CSIRO said on Monday it had analyzed samples of sewage from long-haul flights of returning Australians. They said the poo from the plane proves signals from the SARS-CoV-2 virus can be detected even before passengers show symptoms.

Scientists, working with Qantas and the University of Queensland, have shown that wastewater monitoring can provide valuable data to public health agencies as Australia begins to reopen to the world.

Teams analyzed sewage samples from toilets from 37 Australian government repatriation flights from COVID hotspots, including India, France, UK, South Africa, Canada and the ‘Germany landing at Darwin International Airport between December 2020 and March this year.

Research found that sewage samples from 24 of 37 repatriation flights (65%) showed a positive signal for the virus that causes COVID-19 despite the fact that all passengers (except children of less than five years) tested negative for the virus 48 hours before boarding.

Infected people shed the virus in their poop about two to five days before showing symptoms, says CSIRO. Traces of COVID can also be detected in the wastewater of previously infected people, still shedding the virus, but are no longer infectious to others (although this is usually a weaker signal).

There was 87.5% agreement between positive detections by surveillance of airplane poop.

“This provides an additional layer of data, if there is a possible delay in viral detection in deep nose and throat samples and if passengers are not yet showing symptoms,” said Dr Warish Ahmed of CSIRO .

“Rapid on-site monitoring of wastewater at points of entry can be effective in detecting and monitoring other infectious agents circulating around the world and alerting to future pandemics. “

The work was published today in Environment International.