Chlamydia is a sexually transmitted disease caused by bacteria of the genus Chlamydia. It is caused by having unprotected sex with an infected person. It may be contracted through vaginal, oral, or anal sex. Penetration is not always necessary to transmit chlamydia. You can get this infection by simply touching genitals with an infected person. Sometimes babies contract this infection from their mothers during childbirth.
According to the Centers for Disease Control and Prevention (CDC) , over 1.7 million cases of chlamydia infection were reported in the United States in 2017 alone. This is not a reflection of the actual disease burden. Most cases of chlamydia go unreported, especially because the infection does not typically show symptoms. The CDC estimates that cases may be closer to 3 million yearly .
Most people who have chlamydia do not experience any symptoms. In people who experience symptoms, it typically takes around one to three weeks  for the symptoms to appear. Sometimes the physical signs of this infection take even longer to show. You may have chlamydia for months before the symptoms start to manifest.
The incubation period of chlamydia is determined by several factors. These include how much resistance the bacteria face from your immune system, the number of bacteria that entered your body, the rate at which the bacteria in your system reproduce, and the part of your body through which the bacteria entered.
Sometimes the symptoms appear only for a few days before vanishing on their own. The disappearance of chlamydia symptoms does not always mean the infection has cleared. You may still have the bacteria in your system and infect others.
This article discusses the signs and symptoms of this infection.