Chlamydia

*Chlamydia trachomatis* infects columnar epithelial cells, especially in the cervix, urethra, rectum, and pharynx. The infection may produce little inflammation at first, so many people have no symptoms and can unknowingly transmit it. That silence is the clinical problem. Infection in the lower genital tract can ascend through the cervix into the uterus and fallopian tubes. The resulting pelvic inflammatory disease (PID) can scar reproductive structures, increasing the risk of infertility, ectopic pregnancy, and chronic pelvic pain. In people with testes, ascending infection can cause epididymo-orchitis. A reactive inflammatory arthritis can occur after infection even when genital symptoms have resolved. Chlamydia is not limited to genital exposure. Oral and anal sexual contact can result in pharyngeal or rectal infection, so the site of testing must match the sites of exposure.