Overview of Epididymitis and Orchitis
Epididymitis is inflammation of the epididymis, which is a structure located on top of each testicle (testis). The epididymes are an important part of the sperm development process and are more prone to infection than the testicles.
Orchitis, inflammation of the testicles, usually results from the spread of infection from the epididymis. Most cases of isolated orchitis (i.e., orchitis that develops without epididymitis) are a symptom of the mumps (a viral infection that usually begins in the salivary glands). When epididymitis and orchitis occur together, it is called epididymo-orchitis.
These conditions cause inflammation and pain that is often limited to one, but can involve both sides of the scrotum.
Acute epididymitis, orchitis, and epididymo-orchitis cause sudden pain that usually responds well to treatment. Chronic conditions cause pain that develops gradually and can be more difficult to treat. Acute and chronic cases may result in male fertility problems or testosterone deficiency.
Incidence and Prevalence of Epididymitis and Orchitis
Acute epididymitis is common in young men, and can affect males of any age. Orchitis and chronic conditions are less common. According to the U.S. Centers for Disease Control and Prevention (CDC), epididymitis is especially common in young sexually-active men and is the most common cause of acute (severe) scrotal pain in adolescent males.
In 2004, the CDC noted that approximately one-third of postpubertal (sexually mature) males with mumps develop mumps orchitis, which is the primary cause of isolated orchitis. However, in a 2006 outbreak of mumps in the United States, about 50% of infected postpubertal males developed mumps orchitis, according to the CDC. Mumps is rare in the United States, due to a widely available vaccine, but occasional outbreaks do occur. It is a common disease outside of the United States.