"The Australasian Society for Infectious Diseases (ASID) notes with significant interest the detection of poliovirus in Perth wastewater

This was detected as part of routine wastewater surveillance

The wastewater detection demonstrated evidence of a vaccine derived poliovirus type 2 strain, similar to that detected in various countries in recent years, including in Africa, Europe, and Papua New Guinea

ASID notes that no human cases have been detected, and there is no evidence of spread of disease in Australia

Many overseas countries use the oral polio vaccine, which contains a small amount of live, but weakened virus. Rarely, the virus in the oral polio vaccine can evolve to create a vaccine-derived strain, which can be transmitted in communities with low vaccination coverage.

Australia uses inactivated polio vaccines, which do not contain live virus and are given by injection.

ASID strongly supports health-led approaches to increase wastewater surveillance, alongside bolstering existing approaches to laboratory and clinical surveillance.

Existing polio surveillance, coordinated through the National Polio Surveillance Program, continues to undertake clinical and laboratory surveillance, alongside wastewater testing.

This is a timely reminder of the importance of keeping Australians protected through vaccination – and therefore encouraged everyone to know their vaccination status and if they are under vaccinated against polio and other vaccine-preventable diseases, to discuss with their immunisation provider."

Polio is a viral infection that first targets the stomach and gut. The virus is passed out and present in faeces for several weeks after active infection, which is why it can be found in wastewater. Inactivated poliovirus vaccination is recommended as a routine vaccination for infants and children. Those who receive three doses of inactivated polio virus almost always form antibodies to all types of poliovirus, which means that vaccinated Australians are at low risk of acquiring polio. Adults who are at high risk of exposure to poliovirus (such as healthcare workers, laboratory workers working with the virus or people travelling to countries where poliovirus is active) should also receive booster vaccinations every 10 years. Australia has been declared polio-free since the early 2000s however, from time to time, poliovirus can be found (especially in wastewater) in Australia as it is not yet eradicated in other countries (such as Pakistan and Afghanistan).

Oral polio vaccine is no longer used in Australia. One of the reasons for this is that people can shed the oral vaccine virus in their stools for up to 6 weeks if they are a healthy person, and years if they are immunocompromised. Oral vaccine strains that are shed can then mutate. In places where there are low vaccination rates, the virus can spread from unvaccinated people to other unvaccinated people, and as it does, it can mutate and cause paralysis mimicking the effects of poliovirus in the wild. This mutated virus can then spread and cause what we call circulating vaccine-derived poliovirus (cVDPV). Thankfully, poliovirus vaccination rates with inactivated poliovirus are high in Australia, therefore findings in wastewater such as these are generally of low risk.  Inactivated poliovirus vaccination cannot cause cVDPV.

"Australia has been officially polio-free since 2000, a testament to the success of comprehensive immunisation programs and vigilant public health surveillance. Today, approximately 3,980 polio survivors are registered in Australia (https://www.australianpolioregister.org.au/entries-to-date/).

Previously, the same strain of poliovirus (vaccine-derived poliovirus Type 2 strain) was detected in Melbourne's wastewater on 24 December 2024 (https://www.9news.com.au/national/polio-water-melbourne-vaccine/7ff3540a-d703-4cf8-bb35-22a818fd1cda). As with the last occurrence of poliovirus detection, there is an extremely low risk of transmission to WA residents as the vaccination rate for poliovirus in WA is 92% and that the poliovirus detected from wastewater is likely due to someone returning from overseas travel and has continued to 'shed' the virus.

However, to ensure continued protection against polio among the community, this serves as a reminder for people to be fully vaccinated against the virus while it continues to circulate overseas"

"Since the pandemic and ongoing conflicts globally, we have seen a resurgence of polio, cholera, and measles in many parts of the world. This is partly due to reduction in vaccination rates due to the pandemic, impacts on supply chains, vaccine hesitancy and most importantly misinformation.

The recent detection of polio in our waste water surveillance in Western Australia and Perth highlights the need for additional monitoring. The poliovirus Type 2 strain has in the last two years also been detected in Africa, and PNG as well as in returned travellers in Europe. There needs to be community education and review of vaccination rates in under-fives, especially for travellers from countries at risk in WA.

Polio continues to be of concern in Pakistan and Afghanistan where it is endemic. 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. We can urge those travelling to certain regions to get a booster where needed."

"Vaccine-derived poliovirus Type 2 was detected in a Perth wastewater sample collected in mid-April 2026, marking the first such detection in Australian wastewater. Health authorities believe it most likely originates from an overseas traveller rather than local transmission, and stress the public health risk is very low.

Australia uses inactivated polio vaccines (no live virus), and WA's childhood vaccination coverage sits at 92%, providing strong community protection. Similar detections in Europe in 2024–2025 did not result in any clinical cases. In response, wastewater testing frequency across Perth has been increased, and authorities urge the public to confirm their polio vaccinations are up to date."

"The detection of vaccine-derived poliovirus type 2 in Perth’s Subiaco wastewater is important, but it is not a cause for alarm. It is, however, a timely reminder of the value of wastewater surveillance. Vaccine-derived polioviruses are linked to the live oral polio vaccine used in some countries - not the inactivated polio vaccine used in Australia. The most likely explanation is a returning traveller who is shedding the virus. At this stage, the risk to the broader community remains very low. There is no evidence of clinical polio cases or ongoing local transmission. However, continued vigilance is warranted.

Childhood polio vaccination coverage in Western Australia is around 92%. While high, this is a little below the level typically preferred for very strong population protection. Similar detections in other countries have often not led to cases, but they do underline the importance of maintaining high vaccination coverage and strong surveillance systems."

"Poliovirus at its worst can cause paralysis and death, especially in children. Global vaccination programs over many decades have almost eradicated it, but we are not quite there.

People can get polio in two ways. The first is through "natural" circulating virus. This still occurs in Pakistan and Afghanistan, where there have been challenges with their vaccination programs.

Another way is through infection with mutated forms of virus derived from the oral polio vaccine, which are shed in faeces. It is one of these vaccine-derived strains that have been detected in Western Australian wastewater.

Australia doesn't use the oral polio vaccine anymore, only the injection form, which does not contain live virus. So this means that someone has brought this strain from overseas.

The good news is that in a highly immunised country like Australia, the chance of this vaccine-derived strain of poliovirus causing cases of polio is extremely unlikely.  Furthermore, outbreaks of polio in our region have been few and far between, although they have occurred in the Philippines, Indonesia and PNG.

Another important point is that the detection of poliovirus in wastewater reinforces the importance and success of Australia's surveillance programs against communicable disease."

"Vaccine-derived poliovirus type 2 has been detected in wastewater in Perth; however, this poses a very low risk to the general public. Health authorities have confirmed there is no evidence of transmission in the community, and Western Australia has very high childhood vaccination coverage (around 92%) which makes community transmission very unlikely.

Wastewater surveillance is an important early warning system for protecting public health. The virus detected is not wild poliovirus, but a strain related to the oral polio vaccine. The most likely explanation is that someone who was recently vaccinated overseas has travelled to Australia and is temporarily shedding vaccine derived viral material, which has been detected in sewage testing.

This detection is a timely reminder of the importance of being fully vaccinated against polio, particularly before travelling to regions where the virus still circulates."

"Detection of vaccine-derived poliovirus in wastewater in Perth is significant, but represents a very low risk of further spread of the disease or an outbreak.

Australia previously detected vaccine-derived poliovirus in Melbourne wastewater in 2024, linked to an unvaccinated traveller. Detection in wastewater in Perth is also likely due to an overseas traveller shedding this virus strain.

Similar detections have occurred globally in many countries (e.g., London, New York, Jerusalem), mainly in under-immunised populations, with no subsequent outbreaks.

It is worth noting that while recent detections in most countries are vaccine-derived, wild polio is currently present only in two countries, Afghanistan and Pakistan. So the risk of emergence of wild polio is still there as well. For example, wild poliovirus had been declared eradicated in Africa in 2020 and it re-emerged in Malawi and Mozambique in 2022, with genetic evidence tracing the origin to Pakistan.

However, given Australia’s high vaccination coverage and use of Inactivated Poliovirus Vaccine (IPV), the risk remains low, but continued monitoring and strong vaccination coverage are essential."