Chlamydia infection is a common sexually transmitted infection in humans caused by the bacterium Chlamydia trachomatis. Chlamydia is a major infectious cause of human genital and eye disease. The symptom for chlamydia vary between male and female. In Male: In men, those with a chlamydial infection show symptoms of infectious inflammation of the urethra in about 50% of cases. Symptoms that may occur include: a painful or burning sensation when urinating, an unusual discharge from the penis, testicular pain or swelling, or fever. The purulent penile discharge is generally not as thick and is lighter in color than that for gonorrhea. If left untreated, chlamydia in men can spread to the testicles causing epididymitis, which in rare cases can lead to sterility if not treated within 6 to 8 weeks In Female: Chlamydia is known as the "Silent Epidemic" because in women, it may not cause any symptoms in 70–80% of cases, and can linger for months or years before being discovered. Signs and symptoms may include abnormal vaginal bleeding or discharge, abdominal pain, painful sexual intercourse, fever, painful urination or the urge to urinate more often than usual (urinary urgency).