Orchitis is often caused by bacterial infection and the mumps virus. In young boys, orchitis begins 4-6days after the start of mumps. Boys who develop orchitis from mumps can end up with testicular atrophy(testicles shrink).Orchitis can also occur with infections of the prostate or epididymis(epididymes are tubes on top of the scrotum that transport sperm to the vas deferens).Orchitis may also be caused by sexually transmitted diseases(STD), eg gonorrhea or chlamydia.
Attribution: Straight Talk Foundation