Definition of Prostatitis - nonbacterial:

Nonbacterial prostatitis is an inflammation of the prostate gland with no known cause.

Causes, incidence, and risk factors:

There are many theories about the cause of nonbacterial prostatitis: fungi, viruses, trichomonads, and obligate anaerobic bacteria have been suspected. Irritation caused by a reflux of urine flowing into the prostate may also be a cause.

Up to 65% of patients with chronic prostatitis have the nonbacterial form. The disorder is seen in 5 of every 10,000 outpatient visits by men.