Victoria has increased surveillance testing for traces of the polio virus in wastewater.

Chief health officer Brett Sutton confirmed authorities stepped up testing after a man aged in his 20s was paralysed by the virus in New York earlier this year.

He said the risk of an outbreak in Victoria remained low but was “not out of the question”.

“We’ve got alternating sampling from the eastern and western wastewater treatment plants,” he told ABC radio.

“We need to make sure that we’re looking very closely because we want to detect this at the earliest possible time if it does come here.”

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Professor Sutton said the sensitive surveillance system was capable of detecting tiny amounts of the virus from one individual.

“If it’s detected in wastewater we would try and work out, you know, who it’s circulating in and hit [it] very hard with supplementary vaccination.”

He said Australia was still at a low risk of experiencing an outbreak because about 95 per cent of children were vaccinated.

“That puts us at a much lower risk than some other countries, but there are always pockets of under-vaccination,” he said.

“It’s something that we absolutely want to be ready for. We do not want to be a country where, you know, we’re flagged by WHO as having polio return.”

Professor Sutton said the case in New York and traces of the virus detected in London should be a reminder to every parent to make sure their child is vaccinated.

“If you’ve got unvaccinated kids, you know, it’s a risk and it’s a serious illness, it does cause paralysis in about one in 200.

“That case in New York happened after there will already likely to have been scores and scores of infections already occurring.”

He said Victoria had tested wastewater for traces of the virus for about 20 years.

– AAP