Just finish a game (20+ days) and then save your file, throw all your hoes in the sleezey motel and watch the STD's come rolling in, if there isn't a red plus symbol above their name, send 'em back in for another treatment.
To cure them: send some to the shops and get pills, give it to them.
Herpes: Causes the girl to earn half as much cash from cam shows and half as many fans from photo shoots. Cannot be cured.
Gonorrhea: Prevents the girl from obtaining any talent or style. Curable.
Hepatitis: Prevents the girl from doing any cam shows. Curable.
Syphilis: Prevents the girl from doing any photo shoots. Curable.
Chlamydia: Causes the girl to become stressed out twice as fast. Curable.
AIDS: Prevents the girl from doing anything. Cannot be cured.