Health officials are warning about the importance of vaccinations, after small amount of the polio virus were detected on Melbourne's sewerage system.

Victoria's acting chief health officer Dr. Brett Sutton said the discovery came about during testing of pre-treated sewerage at the Western Treatment Plant in Melbourne.  But it doesn't necessarily mean that someone in Victoria has polio, and the risk of infection to the population is very low.

"Firstly, polio virus usually doesn't cause illness even when infection occurs. Secondly, this polio virus was found at concentrations that do not cause infection. Finally, Australia has very high immunisation coverage and excellent sanitation infrastructure that prevents people being exposed to sewage," Dr. Sutton said as quoted by Fairfax Media.  "There are currently no cases of polio in Australia. The last case of polio was in 2007 in a traveller who acquired the infection in Pakistan.  Victoria hasn't had a locally acquired case since the 1970s."

Aussies 50 or older might remember the scourge of polio, which killed or paralysed thousands of young people around the world every year.  Thanks to global vaccination efforts, the virus has largely been eradicated with documented cases going from 350,000 in 1988 to just 37 reported cases in 2016.