Australian Polymer notes may pose a very small risk, however depending on where you are in the world you might get a different reaction to this issue. Disease experts in northeastern India issued a recent report that said ‘overused and soiled' currency can transmit tuberculosis, pneumonia and other lung infections. British health authorities and travel guides regularly warn tourists in the region to wash their hand following every financial transaction.
Some of the older Rups certainly don't look too healthy. I for one will continue to wash hands regularly & use Aquim gel.