Chlamydia, which is caused by the bacteria Chlamydia trachomatis, targets the cells of mucous membranes including the surfaces of the urethra (male and female), vagina, cervix, and endometrium (the lining of the uterus) as well as the anus and rectum. Although possible, it rarely targets the mouth or throat. If left untreated in women, it can spread to the fallopian tubes and lead to Pelvic Inflammatory Disease (PID), a serious medical condition that can cause infertility.

Chlamydia is transmitted through vaginal or cervical secretions and semen during unprotected anal, oral, or vaginal sex with an infected person. It can also be transmitted from mother to newborn during childbirth.

Chlamydia is not transmitted through such casual contact as hugging, shaking hands, sharing food, using the same eating utensils, drinking from the same glass, sitting on public toilets, or touching door knobs.

Signs and Symptoms:

  • Signs of infection usually appear within one to three weeks after contact. In some cases, infection is obvious only after several weeks or months. Approximately 75 percent of women and 50 percent of men do not have symptoms.
  • Women may experience such symptoms as itching, vaginal discharge, and burning during urination.
  • Some women may experience pain of the lower abdomen or back, pain during intercourse, bleeding between menstrual periods, nausea, or fever if the infection has spread to the fallopian tubes. This may indicate that the infection has progressed to PID.
  • Men may experience heaviness and discomfort in their testicles and inflammation of their scrotal skin. They may also notice pus in the form of a thick white fluid or watery or milky discharge from the penis. Men may also experience pain or burning during urination.



  • Chlamydia is diagnosed through cultures of secretions collected from the urethra, anus, throat, or cervix. It is also diagnosed through urine tests.



  • Chlamydia is curable with oral antibiotics prescribed by a health care provider. All partners should undergo treatment at the same time to avoid passing the infection back and forth. They should also be sure to finish the full course of antibiotics even if symptoms subside.


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  • National Data - CDC's STD Surveillance 2005 Report:
  • In 2005, 976,445 Chlamydia infections were reported to the CDC from 50 states and the District of Columbia for a rate of 332.5 cases per 100,000 people.
  • Nationally, cases of Chlamydia rose 5.1% between 2004 and 2005, from 316.5 cases per 100,000 people in 2004 to 332.5 cases per 100,000 people in 2005.


Data by Sex:

  • In 2005, the overall rate of reported Chlamydia infection among women in the United States (496.5 cases per 100,000 females) was over three times higher than the rate among men (161.1 cases per 100,000 males), likely reflecting a greater number of women screened for this infection


Data by Race/Ethnicity:

  • In 2005, Chlamydia rates increased for all race/ethnic groups.
  • The rate of Chlamydia among blacks was over eight times higher than that of whites (1,247.0 cases per 100,000 versus 152.1 cases per 100,000).
  • The rates among American Indian/Alaska Natives (748.7) and Hispanics (459.0) were also higher than that of whites (4.9 and 3.0 times higher, respectively).


Data by Age:

  • Among women, the highest rates of reported Chlamydia in 2005 were among young women ages 15-19 and ages 20-24 (2,796.6 and 2,691.1 cases per 100,000 females, respectively). These increased rates in women may be, in part, due to increased screening in this group.
  • Chlamydia rates among men were highest in young men ages 20-24 (804.7 cases per 100,000 males).


State, County, and City Data:



Condoms and Chlamydia Prevention
Gabriela Paz-Bailey, et al., "The Effect of Correct and Consistent Condom Use on Chlamydial and Gonococcal Infection Among Urban Adolescents," Archives of Pediatric and Adolescent Medicine, 159.6 (June 2005): 536-542.
Both correct and consistent condom use was reported by only 80 patients (16%).
Correct and consistent use was associated with a significant reduction in Chlamydia.

The full text of this article may be obtained online for a fee. For more information:
See the abstract at the, Archives of Pediatric and Adolescent Medicine, or contact your local librarian.

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