This is actually not one specific disease but a group of infections which all cause urethritis. Urethritis is simply an inflammation of the urethra, the tube that is responsible for allowing urine to flow from the bladder out of the body.
Although it often goes undetected and untreated but without proper treatment, it can lead to pelvic inflammatory disease for women. For men, it will cause testis inflammation which will lead to infertility.
This condition can also be treated with antibiotics. For more severe or complicated cases, we may prescribe a longer than a typical course of antibiotics.