Early-stage Chlamydia trachomatis infections often cause few or no signs and symptoms. When signs or symptoms occur, they usually start one to two weeks after exposure to chlamydia. Even when signs and symptoms occur, they're often mild and passing, making them easy to overlook.

Signs and symptoms of chlamydia trachomatis infection may include:

• Painful urination
• Lower abdominal pain
• Vaginal discharge in women
• Discharge from the penis in men
• Painful sexual intercourse in women
• Bleeding between periods and after sex in women
• Testicular pain in men

Chlamydia trachomatis can also infect the rectum. While these infections often cause no signs or symptoms, you may experience rectal pain, discharge or bleeding.

It's also possible to acquire chlamydial eye infections (conjunctivitis) through contact with infected secretions.

Chlamydia trachomatis is caused by Chlamydia trachomatis bacterium and is most commonly spread through vaginal, oral and anal sex. It's also possible for a mother to spread chlamydia to her child during delivery, causing pneumonia or a serious eye infection in her newborn.

Factors that increase your risk of chlamydia trachomatis include:

• Being sexually active before age 25
• Multiple sex partners within the past year
• Not using a condom consistently
• History of prior sexually transmitted infection

Chlamydia trachomatis can be associated with:

• Other sexually transmitted infections. People who have chlamydia trachomatis are at higher risk of also having other STIs — including gonorrhea and HIV, the virus that causes AIDS.
• Pelvic inflammatory disease (PID). PID is an infection of the uterus and fallopian tubes that causes pelvic pain and fever. Severe infections may require hospitalization for intravenous antibiotics. PID can damage the fallopian tubes, ovaries and uterus, including the cervix.
• Infection near the testicles (epididymitis). A chlamydia infection can inflame the coiled tube located beside each testicle (epididymis). The infection may result in fever, scrotal pain and swelling.
• Prostate gland infection. The chlamydia organism can spread to a man's prostate gland. Prostatitis may result in pain during or after sex, fever and chills, painful urination, and lower back pain.
• Infections in newborns. The chlamydia infection can pass from the vaginal canal to your child during delivery, causing pneumonia or a serious eye infection.
• Infertility. Chlamydia infections — even those that produce no signs or symptoms — can cause scarring and obstruction in the fallopian tubes, which may make women infertile.
• Reactive arthritis. People who have chlamydia trachomatis are at higher risk of developing reactive arthritis, also known as Reiter's syndrome. This condition typically affects the joints, eyes and urethra — the tube that carries urine from your bladder to outside of your body.