Polio Strain Detected in Perth Wastewater, Risk to Public 'Very Low'
A vaccine-derived strain of poliovirus type 2 was detected in a wastewater sample collected in Perth, Western Australia, in mid-April 2026. Health authorities have stated the detection poses a very low risk to the public and does not indicate the spread of the disease. No cases of paralytic polio have been reported.
Detection and Initial Findings
- The positive sample was collected in mid-April 2026 from the Subiaco Wastewater Treatment Plant in Perth.
- This is the first detection of this specific strain in Australia.
- The detected strain is a vaccine-derived poliovirus type 2, similar to strains previously identified in wastewater in parts of Africa, Europe, and Papua New Guinea.
- The finding was made by the national polio surveillance program, which monitors wastewater as an early warning system.
Risk Assessment
- The Western Australia (WA) Department of Health assessed the risk to the population as very low.
- This assessment is based on high vaccination coverage in the state, with approximately 92% of WA children vaccinated.
- Australia uses the inactivated polio vaccine (IPV), which does not contain live virus.
- The detection is considered a single environmental event with no evidence of local transmission.
- The WA Chief Health Officer, Dr. Clare Huppatz, stated the source is most likely a traveler who shed the virus after receiving an oral polio vaccine overseas. She noted that similar detections in European wastewater during 2024-2025 did not lead to any cases of polio.
- The detection does not change Australia's status as polio-free, which has been in place since 2000. No local transmission has occurred since 1972, and the only detected case since 1987 was acquired overseas in 2007.
Response Actions
- The WA Department of Health is increasing the frequency of wastewater testing for poliovirus in the Perth metropolitan area, with plans to test the Subiaco plant and two adjacent sites weekly for six months.
- The department is working with clinicians to enhance hospital-based detection systems for polio.
- The Australian Centre for Disease Control (CDC) reported the finding to the World Health Organization under the National Poliovirus Response Plan.
- The Australian CDC is collaborating with state authorities and expert groups to assess the situation.
Background on Polio and Vaccination
- Vaccine-derived poliovirus can emerge when the live, weakened virus in the oral polio vaccine (OPV) mutates and circulates in under-immunized populations. Australia uses only the inactivated polio vaccine (IPV), which does not contain live virus and cannot lead to vaccine-derived strains.
- Wild poliovirus remains endemic in two countries: Pakistan and Afghanistan.
- Most poliovirus infections are asymptomatic. In a small fraction of cases, it can cause paralysis or death.
- The inactivated polio vaccine is available free under Australia's National Immunisation Programme for children at 2, 4, 6, and 48 months of age. It is also free for catch-up vaccination of people under 20 years old, and for refugees and humanitarian entrants of any age.
"The inactivated polio vaccine is available free under Australia's National Immunisation Programme."
Expert Context
- Professor Jaya Dantas of Curtin University commented on the need for vigilance and consistent vaccination messaging.
- Australian National University infectious diseases specialist Dr. Sanjaya Senanayake noted that global vaccination programs have nearly eradicated polio, but outbreaks have occurred in the region, including in the Philippines, Indonesia, and Papua New Guinea.
- Flinders University epidemiologist Associate Professor Jacqueline Stephens highlighted that WA has high childhood vaccination coverage, around 92%.
"The detection poses a very low risk to the public and does not indicate the spread of the disease."