Viral fragments of the virus were found at wastewater treatment plants at Cairns South, Cairns Marlin Coast, Nambour, Maroochydore, Pulgul at Hervey Bay, Condon at Townsville, and Yeppoon.

Queensland recorded no new coronavirus cases on Tuesday.

However, chief health officer Dr Jeanette Young said authorities were treating the detections seriously.

“A positive sewage result means that someone who has been infected was shedding the virus,” Dr Young said, adding it can happen several weeks after being infectious.

“If there is a case we are not yet aware of, it is critical we detect it through our testing mechanisms as quickly as possible to contain any potential spread.”

She urged Queenslanders in those communities who feel unwell to get tested and isolate.

“Symptoms include fever, cough, sore throat, runny nose, fatigue, diarrhoea, nausea or vomiting and loss of taste or smell,” she said.

More than 6300 tests were conducted in Queensland in the 24 hours to Tuesday.