Chlamydial infections are caused by Chlamydia trachomatis. Infection of the urinary tract, rectum and, exceptionally, throat is caused by serotypes D-K.

Infections of the urethra, vagina and cervix usually progress without any particular symptoms, or the discharge is not noticed by the infected person. An untreated infection may transfer to the ovarian tubes and cause infertility.

In men, a bright slimy discharge and/or a burning sensation in the urethra appears 1 to 3 weeks after infection and disappears without treatment; however, chronic periodic aggravation or even inflammation of the epidydimis or prostate may follow. In the event of rectal infection, as many as 6 weeks may pass before the occurrence of a bloody discharge, painful defecation, fever, lesions in the anal channel, inflammation of the inguinal glands, headache and aching joints. The infection often progresses without any problems.

Chlamydial infections can be efficiently treated with appropriate antibiotics.