Should we still let them play?

A close friend of mine recently told me that her daughter was having stomach issues and was expelling some types of parasite(worm) through her rectum. I was not surprised considering this child eats very little and when she does it's usually unhealthy, but this is beside the point. I told my husband and now he refuses to let our daughter to have any play dates with her daughter. I do not know for a fact that this can or can not be transmitted. I am kind of grossed out, and don't know what to think. Hygiene has always been an issue with this family as well, but now it's an illness. What should I do?