A chlamydia infection is caused by Chlamydia trachomatis bacteria. It is the most common sexually transmitted disease (STD) in the U.S. Many women infected with chlamydia have no symptoms. If there are symptoms, chlamydial infection can be easily confused with gonorrhea because the symptoms of both diseases are similar and the diseases can occur together.

There are several ways to diagnose a chlamydia infection:

• A culture of secretion from the vagina, cervix, fallopian tube, or penis, or urine. It can take up to one week to get results with a culture.
• A chlamydia antibody blood test.
• Testing for the "footprint" of chlamydia, their DNA: Direct fluorescent antibody test (DFA), Enzyme-linked immunosorbent assay (ELISA, EIA), Polymerase chain reaction assay (PCR), and Nucleic acid hybridization tests (DNA probe testing).