Reasons to keep a child out of day care or school include:
The child is lethargic, irritable, tearful, or acting such that he or she is unable to participate in the usual activities.
The child's illness is complex or severe enough that he or she takes all the time of a staff member or teacher.
Fever over 100.4 F.
Diarrhea not contained by diapers or the toilet, stools containing blood or mucus, or bacterial diarrhea (such as E. coli)
A contagious bacterial illness until the child has been on antibiotics for at least 24 hours. Contagious bacterial illnesses include conjunctivitis (pink eye) and strep throat. (Bacterial illnesses such as ear infections and urinary tract infections are not contagious.)
Children shouldn't be excluded for daycare simply for:
A runny nose, even if the mucus is green or yellow
A viral sore throat
One or two loose stools a day, contained in diapers