Samples of sewage taken from Brisbane and the Sunshine Coast have tested positive for coronavirus.
Traces of coronavirus were found in Townsville's sewage earlier this month, which Chief Health Officer Jeannette Young said could have been from an asymptomatic person still shedding the virus.
Wastewater in Townsville, in north Queensland, has since tested negative but samples from October 12 and 13 taken at Sandgate, Maroochydore and Wynnum in the state's south-east tested positive.
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"It could of course be someone who recently had the infection and then has gone to those places, so they're not infectious, they've recovered but they're still shedding virus, it could be that," Dr Young said.
"But it could of course be a person that we've not picked up, that's out there in the community.
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"We have most recently seen, both in Victoria and New South Wales, that when they've had positive results in their sewage, they've gone out then and done more testing and they have found cases.
"That could be happening here in Queensland, so although it's now over a month since we've had an infectious case in the community, we could have an infectious case again any day."
Queensland recorded no new cases of coronavirus overnight.
The state's total remains at 1,164 with four cases still listed as active.
Dr Young said it was "absolutely critical' any new cases were detected as soon as possible for the health system to be able to manage them.
"We don't know how long, someone can continue to shed the virus, we know from other situations you can shed virus for months and months and months, it's probably the case here," she said.
Blood samples from an woman who tested positive, several days after leaving Queensland and arriving in Victoria, have also now tested negative in serology tests.
Dr Young said the samples were taken before the woman left Queensland and before she was showing any symptoms.
"It doesn't confirm anything but it just suggests that she didn't have the infection while she was in Queensland," she said.
The woman had visited several locations in Townsville and Cairns, including medical facilities, before flying to Melbourne on October 7 .
Dr Young said Queensland Health was still waiting on results from tests in Melbourne to confirm the woman's case.
Days since the last reported case of COVID-19
NSW
0
SA
0
VIC
0
WA
0
QLD
1
TAS
67
NT
77
ACT
99
Last updated 5:50 AM AEST on Sunday, October 18
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