Several players are affected, including captain Louis Carey. The defender`s calf problem has responded well to an injection but illness could now postpone his comeback after almost six weeks on the sidelines.
"We've had to tell some of the lads to stay away because we cannot risk them coming into contact with the group," said City boss Keith Millen.
"It's easy to pass it on and a lot of the players and staff have gone down with it in the last week or so.
"This is a busy time of year and, with four games in nine days, we need everybody to be available. It's a matter of being sensible and taking the right precautions."
Meanwhile, defender Liam Fontaine remains out with an ankle injury.
Source: PA
Source: PA