Chlamydia is a sexually transmitted disease (STD) that is caused by the bacterium Chlamydia trachomatis. Because approximately 75% of women and 50% of men have no symptoms, most people infected with chlamydia are not aware of their infections and therefore may not seek health care.

When diagnosed, chlamydia can be easily treated and cured. Untreated, chlamydia can cause severe, costly reproductive and other health problems which include both short- and long-term consequences, including pelvic inflammatory disease (PID), which is the critical link to infertility, and potentially fatal tubal pregnancy.

Up to 40% of women with untreated chlamydia will develop PID. Undiagnosed PID caused by chlamydia is common. Of those with PID, 20% will become infertile; 18% will experience debilitating, chronic pelvic pain; and 9% will have a life-threatening tubal pregnancy. Tubal pregnancy is the leading cause of first-trimester, pregnancy-related deaths in American women.

Chlamydia may also result in adverse outcomes of pregnancy, including neonatal conjunctivitis and pneumonia. In addition, recent research has shown that women infected with chlamydia have a 3 - 5 fold increased risk of acquiring HIV, if exposed.

Chlamydia is also common among young men, who are seldom offered screening. Untreated chlamydia in men typically causes urethral infection, but may also result in complications such as swollen and tender testicles.

1. Rates are per 100,000 population.

Resource: CDC.