Chlamydia is caused by a germ that is spread by having sex with an infected person. Chlamydia infection is the most common sexually transmitted disease in the world. Chlamydia may infect men and women. Every sexually active person can get infected with chlamydia.
Babies can get chlamydia during birth if the mother is infected at the time of delivery.
Symptoms of chlamydia infections may appear within two weeks to a month after exposure to someone with the infection. Symptoms may be present early in the day and go away, only to return. The only way many people learn that they may have chlamydia is if a sexual partner has told them they have been exposed. The only sure way is to get a diagnosis from a health care provider. From the time a person is infected, he or she can spread the disease.