The highly contagious and deadly poliovirus has been detected in Perth’s wastewater, marking the first time that the disease has been found in Australia in close to two decades.

WA Health confirmed that the vaccine-derived Type 2 poliovirus strain was identified in a sample taken from the Subiaco Wastewater Treatment Plant in mid-April.

The same strain has previously been identified in parts of Africa, Europe and Papua New Guinea.

Staff from the National Laboratory in Melbourne notified WA Health of the discovery, before the Centers for Disease Control and Prevention in the United States were consulted on how to respond to the incident.

“This is the first time that we’ve had a detection like this in Perth,” WA Chief Health Officer Dr Clare Huppatz said.

“We really wouldn’t know where this has come from in terms of the person that might have been involved with this.”

Authorities believe the virus sample is most likely linked to a person from overseas who may have come from a region where oral polio vaccines are used.

“When you’ve been exposed, you can shed for quite some time, and they’ve probably come back to Australia after shedding. It’s very possible that they have also left,” Dr Huppatz said.

Testing on the Subiaco treatment plant and two adjacent sites will be increased to weekly testing for the next six months.

The vaccine-derived Type 2 poliovirus is contracted primarily through the fecal-oral route, when infected fecal matter is ingested.

Most people won’t experience symptoms but in rare cases the disease causes paralysis or death.

Similar detections have been made in other countries, including across Europe, and have not led to outbreaks, Dr Huppatz said.

“It is a timely reminder that polio virus is still circulating around the world. And of course, with international travel, it is something that people could be exposed to, even in Perth,” she said.

“The best way to ensure that you’re protected is to be vaccinated. Poliovirus is one of the vaccinations in the normal routine childhood vaccination campaign. So I would just really encourage all parents to make sure their children are up to date with their vaccinations, and if other people want to check their vaccination status, they can do that through MyGov or with their local doctor.”

Curtin University’s Professor Jaya Dantas, from the school of population health, described the urgent need for vigilance around vaccination.

“Polio continues to be of concern in Pakistan and Afghanistan where it is endemic,” she said.

“Whilst we have a great health system in WA and with the Australian CDC commencing and setting up its advisory council – we need to remain vigilant and ensure that our messaging about vaccination and its long-term benefits is consistent, strong and ongoing and be supportive of those most at risk.”