But coach Tim Sheens said he hoped the outbreak was under control and was confident the Kangaroos will field their top side in Saturday's decider (November 15) in Wellington.
"We've had a bit of disruption this week with that bug in the camp, but we're confident going into the weekend's game," Sheens told reporters.
Medical staff have isolated the ill players, who were not named, in an attempt to prevent the virus sweeping through the rest of the team.
The virus has disrupted the Kangaroos' build-up since they arrived in Wellington this week after a late qualification for the final when they beat Samoa 44-18 in Wollongong last Sunday (November 9).
The world champions suffered a shock loss to the unbeaten Kiwis in the first round before bouncing back with wins over England and then Samoa, but Sheens believes it will be tough to maintain the momentum with the short turnaround between games.
"I don't think anyone gave us much chance and certainly after game one, they gave us no chance," he said. "Now some are saying we're favourites, although I don't know how they figure that. AFP