I am a bigtime germ fanatic. I make sure my son tries not to put the fingers in the mouth, ect. Just by touching the feet, that walk along ANY dirty surface of ANY place... they can get something after touching the face.
Ringworm is usually triggered if there is a cat in the mix... typically from the litter box. This is contagious!
As for the childcare setting... Did you ask if anyone was ill when you brought your child in? Sickness does not develop until about two days later for most cases. It takes this long for the 'germ' period to incubate.
Do not forget... Other parents will not abide by the rules. I had my child in the hospital for a week previously with a sickness similar to the Rotovirus. Not fun and it was from a changing table. (Even if you forget to wash your hands, it / germs can spread.)
At this point, just be there for your child and take your own precautions for the ringworm... Best of Luck!