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. Chlamydia infection is one of the most common sexually transmitted infections worldwide. Chlamydia can be transmitted during vaginal, anal, or oral sex, and can be passed from an infected mother to her baby during childbirth. In men, infection by C. trachomatis can lead to inflammation of the penile urethra causing a white discharge from the penis with or without a burning sensation during urination. Later it spreads to the epididymis in men. Whereas women will have infection of the cervix without symptoms and may not realize they are infected. It later spreads to upper genital tract in women.The major research centers for Chlamydia is NIAID research center at the Institute's Rocky Mountain Laboratories in Hamilton, Montana.