E.B.
ringworm is very contagious. however there are some people who get it because they are immuned to it than others. my sister works at a vet and she gets ringworm the moment she works with a dog/cat that has it because she's proned to it. my son has had it three times and i haven't caught it. There isn't anything you can really do to protect him from getting it other than not sending him out to play. but please be informed, you can get ringworm from the barber, a shopping cart, the playground and many other places but it's so contagious. if he doesn't get the ringworm at all more than like he might not be one of those who gets it all the time or so easily. i grew up playing in dirt my whole preteen life and never got it but friends and cousins were always around me and they had it. if he does develop it i use lanisol cream (athletes foot cream) on my son and in three days its gone. lanisol treats the fungus in athletes foot and ringworm is a form of fungus. you can read up on ringworm to learn more about it. but i wouldn't be too overprotective about it because he can get it from anything else.
To add: If the parent knows that the cat has ringworm more than likely he is being treated by a vetinarian. Also, I wouldn't recommend my kids playing out with others if they had the ringworm to prevent from it spreading to them.