Double edged sword. First the right thing is to be truthful and if you get the (insert STD here) then would it not be in the best interest of the people in the hobby to let it be known? Sure her business will be impacted but such is a risk of the hobby is it not?
And the flip side... I am sure some trick/pimp/hooker/who knows at one point in time has done this to some trick/hooker/pimp/who knows just to get even with them for some unknown wrong the accused did (or what ever reason they cook up) which would be why it is a nuclear subject here (well besides creating mass hysteria)..
So the best way to do this if it actually happens to either a customer or provider would be via PM. Thankfully a lot is exchanged via PM here. Less drama that way.