Untill an infant is up walking around and getting into mischif, i doubt they would be exposed to the tic vector. I believe it must attach and feed for 24 hr before it will pass its germ.Most parents would notice a tic during bathing.
That said, I have seen it in a 15 mo. The primary bite wound and secondary target ring lesion were dramatic. In infants a ring worm would be more likely.