Facts about Chlamydia

What is Chlamydia?

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 (also called "pink eye") and pneumonia. In addition, recent research has shown that women infected with chlamydia have a 3- to 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.

Number of Chlamydia Cases

Chlamydia is the most frequently reported infectious disease in the United States. Though 526,653 cases were reported in 1997, an estimated 3 million cases occur annually. Severe under reporting is largely a result of substantial numbers of people without symptoms whose infections are not identified because screening is not available. Highlights of reported data are as follows:

• From 1984 through 1997, reported rates(1) of chlamydia increased from 3.2 to 207.0 cases per 100,000 people. This trend primarily reflects increased screening, recognition of asymptomatic infection (mainly in women), and improved reporting capacity rather than a true increase in disease incidence.
• In 1997, the reported rate of chlamydia for women (335.8) substantially exceeded the rate for men (70.4), due mainly to increased detection of asymptomatic infection in women through screening. Low rates of reported chlamydia among men suggest that many of the partners of women with chlamydia are not screened or treated.
• As in previous years, 1997 rates of chlamydia were highest in the West and the Midwest, where substantial resources have been committed for organized screening programs.

Chlamydia's Impact on Young Women

• As many as 1 in 10 adolescent girls tested for chlamydia is infected.
• Based on reports to the CDC provided by states that collect age-specific data, teenage girls have the highest rates of chlamydia. In these states, 15- to 19-year-old girls represent 46% of infections and 20- to 24-year-old women represent another 33%. These high percentages are consistent with high rates of other STDs among teenagers.
• Among women entering the Job Corps in 1997, chlamydia rates ranged from 4 - 14% by state (20,000 entrants are screened annually). Chlamydia is widespread geographically and highly prevalent among these economically disadvantaged young women between 16 and 24 years old.