An "acute" case is most often caused by an infection from bacteria. The e-coli bacteria are a common cause for infection.
- In children who haven't reached puberty, the infection may start in the bladder or kidney. It then spreads to the teste. Some boys get more urinary tract infections, and may get this more often.
- In men, a STD (sexually transmitted disease) is one of the causes. Mostly from chlamydia, mycoplasma or rarely gonorrhea. These infections start in the urethra. They can then move into the teste. Sometimes there is a discharge of fluid from the urethra.
Sometimes it is caused by something else:
- Enlarged prostate blocking the bladder
- Infection of the prostate gland ("bacterial prostatitis")
- Partly blocked urethra
- Recent catheter use
Epididymitis is sometimes caused by other things:
- Chemical or inflammatory non-bacterial epididymitis may happen from urine flowing backwards to the epididymis. This is most often from heavy lifting. The urine causes swelling but no infection.
- The drug "Amidarone" can be a cause but this is rare
- An infection from the bloodstream (as with tuberculosis)
- Other unknown causes
In any of these cases, the first sign of a problem is often pain in the back of the teste.
A "chronic" case may result after acute epididymitis. It doesn't seem to go away. It can also happen without acute symptoms or known infection. In this case, the cause is unknown.
Orchitis alone is mostly from a mumps virus (or other virus) infection. "Mumps orchitis" appears in about 1/3 of males who get mumps after puberty. It only occurs in boys that have mumps AFTER puberty. In some cases of mumps, interferon can be given to prevent orchitis. This infection doesn't spread to the epididymis.
Acute epididymo-orchitis is most often from a bacterial infection. It can also be caused by a tuberculous infection of the epididymis, but this is rare. Rarely, it can start in the teste and spread to the epididymis.