Thank you for your query. I would love to help to you with that. As you said in your question itself that the sexually transmitted diseases also known as Stds are responsible behind causing urethral discharge in males but there are other infections also which might cause urethral discharge. One of that is the infection in urinary tract. It leads to discharge. Also, it might also lead to burning sensation during urination, frequent urination from time to time, disturbance in the abdomen and slight fever making the person sluggish and pale. This infection is not very dangerous and with proper medication under the supervision of a doctor it can be treated fully. The best way to confirm whether the discharge is because of urinary tract infection or Stds is to have a proper urine test at the nearest pathology confirmed by the doctor. Coming to your second question; this is one of the most common questions. Sexually transmitted diseases as the name suggest are caused when two people have sexual relation with each other, during the time of intercourse between those two people, these diseases are caused. A person suffering from a sexually transmitted disease if has intercourse with person not suffering from it then he might pass on his disease to that unaffected person if there is no use of protection. Hence, in order to be on the protected side it is advisable that whenever you have sex with unfamiliar people like a sex worker, you should always wear protection like condoms. This will not only prevent you from getting infected by sexually transmitted diseases but will also give you peace of mind while having sex. I hope your queries are sorted. Take care.