Insist on a change of clothes for at your house and put those on him for play and keep them at your house. Yes they could very well be on his clothes - pockets cuffs - anywhere dark. Probably not as likely in the sense of if they are clean clothes he is wearing they won't have come in contact with too many surfaces where the fleas are.

While it may not be like lice in terms of them being on the child it is the same in that if only a few arrive at your house they will trive quite nicely in your carpets and couches and multiply so the problem could be coming to you.

The fact the child knows all about them and the name and can talk about them tells you that it is a problem at their house so yes I would confront the parents and let them know what steps need to be taken care of. Not sure if your local health unit or some other agency would have advice on how you should deal with the child coming into care in terms of precautions.

If you find some bites then send the child home due to "rash" till he has been seen by a doctor and it varified in writing for him to return. At that point the doctor will advise the parents on measures to take.
Also just reread your post and it sounds like the child actually had a flea he brought to daycare from home - sorry for the impromtu show and tell. I might also visit the pet store to look at some products and talk to staff there about treating your own house. There is a powder you can sprinkle and vacuum I think and well you might just feel better if you do that.