Orchitis is an inflammatory condition of one or both testicles in males, generally caused by a viral or bacterial infection.Most cases of orchitis in children are caused by infection with the mumps virus.Orchitis caused by a bacterial infection most commonly develops from the progression of epididymitis, an infection of the tube that carries semen out of the testicles. This is called epididymo-orchitis.The majority of cases of mumps orchitis occur in prepubertal (less than 10 years old) males, while most cases of bacterial orchitis occur in sexually active men, or in men older than 50 years of age with benign prostatic hypertrophy.
