Too much information

So is it possible to tell someone, tactfully, that said person is a bit too interested in my private life?  Can I say I prefer to keep our relationship professional?  Or is that too harsh?  The person isn't taking my non-committal answers or evasiveness as a clue.  Instead, the person just continues asking questions that I feel are somewhat inappropriate given our relationship.  You see, this person is my TA (and yes, feel free to hate me for having a TA; I hate myself a little bit).  Given that, I don't feel it is appropriate for this person to ask about really personal stuff. Nor do I want to know really personal things about the TA.  For example, the TA just called me to say s/he's missing class.  Saying, "I'm not feeling well" is more than sufficient, but instead, this person felt the need to go into detail regarding the severity of the stomach flu that has afflicted hir.  For real.  I don't need to know that.   Just sayin'.