A strain of polio has been detected in a wastewater sample in Perth, sparking fears the deadly disease has returned to Australia 26 years after it was eliminated.

Polio is a highly contagious infection caused by the poliovirus which can cause long-term disability, paralysis and death.

There is no cure for the illness, but it can be prevented with vaccination.

Australia has been polio-free since 2000, with the last locally-acquired case recorded decades before in 1972.

But, on Friday, the WA Government's Department of Health reported that its surveillance program had detected poliovirus in a wastewater sample taken from a catchment in Perth in mid-April.

The monitoring system offers early warnings of potential outbreaks.

Evidence was found this week of a vaccine-derived poliovirus Type 2 strain, similar to what has been detected in various countries over the last few years, including in Africa, Europe and Papua New Guinea. 

While polio is a serious virus, WA's Chief Health Officer Dr Clare Huppatz said the single detection was considered a very low risk to the public.

'The potential for this strain to circulate in a highly vaccinated population is very low, and the poliovirus vaccination coverage in WA children is 92 per cent,' she said.

'While this is a significant finding, this detection does not provide evidence of spread of the disease in WA.'

The presence of the virus in wastewater in Europe during 2024 and 2025 did not lead to anyone developing the disease.

'This finding is most likely from someone who has travelled overseas and is shedding this virus strain,' Dr Huppatz added.

'Fortunately, Australia has an excellent vaccination program against poliovirus which will protect the community against this strain.

'This does however serve as a timely reminder that poliovirus continues to circulate in other countries, and the importance of making sure you and your family are fully vaccinated.'

Before vaccines were introduced, polio was a major cause of death and disability.

But, thanks to global eradication efforts, annual cases have declined by over 99 per cent since the 1980s. 

Although the risk of polio in Australia is low, health authorities recommend vaccination, as outbreaks sometimes occur in neighbouring countries. 

Most people with poliovirus infection have no or mild symptoms.

However, a very small number of cases can progress to paralysis, which may involve severe muscle pain, weakness, and involuntary movements.

The WA Department of Health said it is increasing wastewater testing across metropolitan areas and working with clinicians to improve systems detecting possible polio cases in hospitals.

Free polio vaccines are available under the National Immunisation Program for children, eligible people under 20, and refugees and humanitarian entrants of any age.