However, the Queenstown Lakes District Council is powerless to do anything more about the problem, chief executive Adam Feeley says.
During the open forum at this week's Wanaka Residents' Association annual meeting where Mr Feeley was guest speaker, Dr Pezaro called for tougher penalties against freedom campers, in light of concerns shared by health officials worldwide about predicted norovirus epidemics.
''Norovirus is expected to sweep the northern hemisphere in their summer and it will inevitably find its way south,'' Dr Pezaro told the meeting.
''Only 40 years ago we were taught there was no giardia,'' he said.
Yet pollution from poorly disposed toilet waste now meant New Zealand's streams were ''unreliable'' and freedom camping could cause the same devastating result with the norovirus stomach bug.
''My concern is that if you allow people to continue to camp with inadequate toilet facilities then goodness know what this norovirus will do ... I'm very concerned that it could disable communities and community water supplies.''
Although he appreciated what the QLDC was doing to address the freedom camping issue, ''I do think we need to strengthen our resolve''.
''We must stamp [freedom camping] out before it starts to beat us.''
However, the council had limitations under the Freedom Camping Act in what it could do, Mr Feeley said.
''What you want is a law to stop people breaking the law,'' he told Dr Pezaro.
''We can only exercise the powers that we've got.
''We simply do not have any power to do any more than what we are doing.
''We share your pain, we don't enjoy it any more than you do.''
If freedom camping issues did not improve in the next couple of years, it might be necessary to lobby central government for changes to the Act, he said.
''I think in reality we will have to go back and say `It's not working as well as it should, we have to change it'.''
A new strain of the norovirus stomach bug that has hit New Zealand was linked this week to a death in Northland.
