Poliovirus wastewater testing established amid heightened global risk

News article

21 April 2023

ESR (Institute of Environmental Science and Research) and Manatū Hauora have this week established routine poliovirus testing in wastewater following a successful three-month pilot.

Director of Public Health Dr Nicholas Jones confirms Aotearoa continues to be polio-free.

“The decision to introduce poliovirus wastewater testing is in response to the increased risk of poliovirus globally. In November 2022, WHO (World Health Organization) advised of an increase in polio activity in areas which have previously seen polio eradication. 

“During the COVID-19 pandemic childhood immunisation coverage fell globally, including in Aotearoa. This means that if poliovirus enters Aotearoa, the risk of it spreading and causing disease, especially in younger children, is greater than it was in pre-COVID-19 years,” Dr Jones says.

There is no cure for polio disease and for some people, it can be debilitating and even fatal. People who survive can be left with lifelong disability and other complications. 

“Vaccination dramatically reduces the risk from polio so it’s important that people are up to date with their vaccinations in the event that polio does re-enter Aotearoa.”

In New Zealand, children are immunised against 13 preventable diseases, including polio, whooping cough, chickenpox and measles. These immunisations are free for babies, children, adolescents, and pregnant people.

“If you are the parent or caregiver for a child who may not be fully immunised, or you are unsure, please contact your family doctor or nurse to arrange vaccination.”

Wastewater testing can detect different types of poliovirus – some of which are disease causing and some of which are not. When poliovirus is detected, further testing occurs to identify the type of poliovirus. For example, when someone has recently had oral polio vaccine (OPV), they can excrete non-disease-causing viruses in faeces and this can be detected in wastewater.

Aotearoa and most developed countries no longer use OPV but it is still used in some developing countries.  The polio vaccine used in New Zealand is an inactivated vaccine which means the virus is killed off.    

“Wastewater testing for poliovirus is already routine in many countries, including Japan and Australia, and now it is established it could help us identify the presence of poliovirus in New Zealand before any individual cases of polio are detected.

“Having this tool available has already yielded the first detection earlier this week of a non-disease-causing type 3 vaccine strain, or a Sabin-like virus, in a wastewater sample. This was likely being shed by someone who had recently been vaccinated overseas with an oral polio vaccine.

“This is an expected finding and does not pose a public health risk. The results provide assurance that wastewater testing is an effective tool to support detection of poliovirus in New Zealand.”

Wastewater testing complements existing polio surveillance, including national reporting of patients with Acute Flaccid Paralysis (when muscles do not work suddenly), a possible indication of polio. Wastewater surveillance is part of a broader move by Te Whatu Ora – Health New Zealand, Te Aka Whai Ora – Māori Health Authority, and Manatū Hauora – the Ministry to review our national polio preparedness including surveillance, case identification, testing and notification, and planning.

Poliovirus testing is currently being carried out on wastewater samples collected from Auckland, Wellington, Christchurch, and Queenstown.

Find more resources about how to access a vaccination: Immunise .

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