They don't allow sick kids -- fever, etc. to stay. They have to go home. Lot of times it's just a warning. If we were really really nervous about something, we'd probably keep him home, but there hasn't been anything too scary. Despite DS's cf, he's still going to catch a cold from time to time, just have to be vigilant.
DS has had his chicken pox vaccine -- all the kids have to be vaccinated to go to daycare. But a child in another room, got chicken pox anyway.
Stomach flu/the runs was going around. Everyone was warned that any child with loose stools, upset stomach was going to be sent home. Usually they spend the night disinfecting the place.
A couple years ago when whooping cough/pertussis hit our state pretty bad. An older child got it, so the director had to call all the parents and all children and staff were put on zithromax. I called my doctor at 10:30 at night and had a script waiting for me at the pharmacy -- other parents had to wait all day for a call from their doctor's office and had to stay home or make other arrangments. liza
If DS has a fever, either DH or I stay home with him or take him to the doctor. Last time he had an ear infection, I took him to the clinic and then my in-laws watched him the rest of the day.