How do I know if a hostess is infected or not? My wife wont have sex with me.

YOu can't know. There is no good way to know whether or not someone else has a sexually transmitted infection. If you are having sex with a prostitute, you should just assume they are infected. I suggest you and your wife see a therapist to discuss your problems. I recommend against seeing a "hostess" for sex; it is extremely dangerous. If you must, condoms offer some (but not complete) protection.