Does your library have a policy/procedure in place for when a visibly sick patron comes in to use the library?

Are we able to ask them to leave?  

I don't want to infringe on anyone's rights to use the library, but we have to protect our staff and patrons.  When someone comes in coughing and obviously ill with a cold, flu, or whatever, what can be done?

Thanks for your wisdom!

Perri