Colds and flu?  I'm fanatic about it.  If there is a family gathering where I know a child there has a fresh cold, we don't go.  If we go to church and I see a kid in Sunday school with a runny nose, I don't put my son in the class.  It is just that most illnesses for our 4 year old end-up with trips or near trips to the hospital.  His condition is well managed, maybe to the point of being slightly oversurpressed. 

Also, I've become a germa-phobe!  How do other parents balance the normal development of their child with avoiding illness?