What is Chlamydia?

Chlamydia is the most commonly reported infectious disease in the United States. It is caused by the bacterium chlamydia trachomatis. In 2005 nearly a million cases were reported, but most cases go undiagnosed, and so the CDC estimate that about three million infections occur each year in the United States.[1] The disease is found primarily among teenage girls and young women. In fact, nearly three out of every four cases of chlamydia in women are found in girls between the ages of fifteen and twenty-four.[2] It is estimated that 40 percent of sexually active single women have been infected at some time with chlamydia.[3] (However, since the disease is curable, this does not mean that 40 percent of women are currently infected.) The disease is so common that there are more cases of chlamydia reported than all cases of AIDS, chancroid, gonorrhea, hepatitis (types A, B, and C), and syphilis combined![4] This STD can also be spread by means of oral sex.[5] Some of the symptoms of genital chlamydial infection include vaginal or urethral discharge, burning with urination, pelvic pain, and genital ulcers. Men can experience many of these symptoms, and also tenderness of the scrotum. In many cases the man will experience no symptoms, despite the fact that the STD can damage his fertility.[6] Sometimes a chlamydial infection can lead to sterility in men, although this is not common.

As is the case with most STDs, women are more likely to suffer serious consequences of chlamydial infection. For example, chlamydia may spread to a woman’s uterus and fallopian tubes, causing pelvic inflammatory disease (PID). This can lead to infertility and may become a life-threatening infection. One way it can be deadly is by increasing a woman’s risk of having an ectopic pregnancy, where the newly conceived baby implants outside of the uterus. One reason this can happen is that PID can scar the fallopian tubes, making it more difficult for a newly conceived baby to be transferred through them to the womb. If the baby gets stuck in one of the tubes and the condition is not treated, it can be fatal for the mother because the fallopian tube can burst.

Ectopic pregnancies account for less than 2 percent of all pregnancies, and the vast majority of these women survive. But the complications that can arise from the condition make it the leading cause of maternal death in the first trimester of pregnancy.[7] Each year more than a million American women experience PID.[8] According to the CDC, “Up to 40 percent of females with untreated chlamydia infections develop PID, and up to 20 percent of those may become infertile.”[9] Unfortunately, most women (and half of men) who are infected with chlamydia show no symptoms.[10] Consequently they may not receive treatment with the necessary antibiotics.

Additionally, the screening test for chlamydia may miss the infection, and the woman can be given what is called a “false negative” diagnosis. In other words, she is told that she does not have chlamydia, despite the fact that she is infected.[11] Even when diagnosed accurately, the antibiotics prescribed may stop the bacteria from reproducing, but the disease may reactivate later. Years after the initial infection, the disease can still be present in the woman’s fallopian tubes, without symptoms.[12]

Even when the disease is treated, its effects may linger. While in a woman’s body, chlamydia causes the production of heat shock protein (HSP). Especially when a woman has a prolonged chlamydial infection without knowing it, her immune system creates antibodies against the HSP. This means that her white blood cells learn to attack HSP, because they associate it with chlamydia. If the woman becomes pregnant, this creates a problem. One of the first proteins made by an embryo is a type of HSP similar to the one made by chlamydia. Because the chlamydial infection trained her immune system to be hostile to HSP, her immune system may react against her baby. This can interfere with the development of the embryo. It can also leave the embryo less protected, making the unborn child more likely to die before implanting in the uterus.

Finally, it can create an inflammatory reaction in the uterus. This may cause a “spontaneous abortion” or miscarriage.[13] In one study of 216 women with infertility problems, 21 percent of them tested positive for chlamydial HSP antibodies, despite the fact that none of them knew that they had ever been infected.[14] Larger studies of women with fertility problems estimate that between 30 and 60 percent of them have chlamydia antibodies in their serum (blood plasma), indicating that they had been infected with chlamydia at some point in the past.[15] A teenager may contract chlamydia, never show symptoms of the infection, and then experience fertility problems ten years later when she and her husband try to conceive a baby. For all of these reasons chlamydia is called the “silent sterilizer.”

Because of the physical nature of STDs, the emotional consequences of the infections are often overlooked. One woman said, “Sometime during my wild college days, I picked up an infection that damaged the inside of my fallopian tubes and left me infertile. I am now married to a wonderful man who very much wants children, and the guilt I feel is overwhelming. We will look into adoption, but this whole ordeal has been terribly difficult.”[16] Should a woman contract chlamydia and conceive successfully, it is possible for her to pass the infection on to her baby. This can lead to blindness, pneumonia, or premature birth.[17] Even when a woman receives treatment for chlamydia, doctors are encouraged to follow up with her three months later.[18] This is because many girls get reinfected from their untreated partner(s).

Because of how the disease compromises a woman’s immune system, women with chlamydia are up to five times as likely to become infected with HIV, if exposed,[19] and are more likely to develop cervical cancer from HPV.[20] One rare form of chlamydia is known as Lymphogranuloma Venereum (LGV). This disease may cause a person’s lymph nodes in the groin to swell up to the size of a lemon and burst. LGV is not nearly as common as chlamydia, but it has been detected especially in people who engage in high-risk sexual behaviors.

Consistent and correct condom use may reduce (but not eliminate) the risk of being infected with chlamydia, but the degree of protection offered by the condom is not certain. According to the most comprehensive research on condom effectiveness for STD prevention, the National Institutes for Health reported, “Taken together, the available epidemiologic literature does not allow an accurate assessment of the degree of potential protection against chlamydia offered by correct and consistent condom usage.”[21] Since the time of this report, other studies have suggested that condom use may decrease the risk of chlamydia infections by about half.[22]

[1]. “Trends in Reportable Sexually Transmitted Diseases in the United States, 2005,” 1.
[2]. “Trends in Reportable Sexually Transmitted Diseases,” 2.
[3]. Joe McIlhaney,M.D., Safe Sex (Grand Rapids,Mich.: BakerHouse Books, 1992), 103.
[4]. Medical Institute for Sexual Health, “Sexual Health Update,” 7:2 (Summer 1999), 1.
[5]. S. Edwards and C. Carne, “Oral Sex and Transmission of Non-Viral STIs,” Sexually Transmitted Infections 74:2 (April 1998), 95–100.
[6]. S. S. Witkin, et al., “Relationship Between an Asymptomatic Male Genital Tract Exposure to Chlamydia Trachomatis and an Autoimmune Response to Spermatozoa,”Human Reproduction 11 (November 10, 1995), 2952–2955; R. Gdoura, et al., “Chlamydia Trachomatis and Male Infertility in Tunisia,” The European Journal of Contraception & Reproductive Health Care 6:2 (June 2002), 102–107; A.A. Pacey and A. Eley, “Chlamydia Trachomatis and Male Fertility,” Human Fertility 7:4 (December 2004), 271–276.
[7]. Tatiana Goldner, et al., “Surveillance for Ectopic Pregnancy—United States, 1970–1989,” MMWR Weekly 42:SS-6 (December 17, 1993) 73–85; “Current Trends Ectopic Pregnancy—United States, 1990–1992,” Centers for Disease Control, MMWR Weekly 44:3 (January 27, 1995), 46–48.
[8]. Centers for Disease Control, “Pelvic Inflammatory Disease,” Fact Sheet (May 2004).
[9]. “Trends in Reportable Sexually Transmitted Diseases, 2005,” 1.
[10]. “Tracking the Hidden Epidemics, Trends in STDs in the United States 2000,” CDC, 6.
[11]. Jolande Land, et al., “Chlamydia Trachomatis in Subfertile Women Undergoing Uterine Instrumentation,” Human Reproduction 17:3 (March 2002), 526.
[12]. Land, et al., 525–527; S.D. Spandorfer, “Previously Undetected Chlamydia Trachomatis Infection, Immunity to Heat Shock Proteins and Tubal Occlusion in Women Undergoing In-Vitro Fertilization,” Human Reproduction 14:1 (January 1999), 60–64; J. Debattista, et al., “Immunopathogenesis of Chlamydia Trachomatis Infections in Women,” Fertility and Sterility 79:6 (June 2003), 1273–1287.
[13]. S. S. Witkin, et al., “Unsuspected Chlamydia Trachomatis Infection and In Vitro Fertilization Outcome,” American Journal of Obstetrics and Gynecology 171:5 (November 1994), 1208–1214; A. Neuer, et al., “The Role of Heat Shock Proteins in Reproduction,” Human Reproduction Update 6:2 (2000), 149–159; S. S. Witkin, et al., “Immune Recognition of the 60kD Heat Shock Protein: Implications for Subsequent Fertility,” Infectious Diseases in Obstetrics and Gynecology 4 (1996), 152–158; A. Neuer, et al., “Humoral Immune Response to Membrane Components of Chlamydia Trachomatis and Expression of Human 60 kDa Heat Shock Protein in Follicular Fluid of In-Vitro Fertilization Patients,” Human Reproduction 12:5 (1997), 925–929; A. Neuer, et al., “Heat Shock Protein Expression during Gametogenesis and Embryogenesis,” Infectious Diseases in Obstetrics and Gynecology 7 (1999), 10–16.
[14]. A. Neuer, et al., “The Role of Heat Shock Proteins in Reproduction,” Human Reproduction Update 6:2 (March/April 2000), 149–159.
[15]. Land, et al., 525–527; C.M. J. Mol, et al., “The Accuracy of Serum Chlamydial Antibodies in the Diagnosis of Tubal Pathology: A Meta-Analysis,” Fertility and Sterility 67:6 (June 1997), 1031–1037.
[16]. Thomas Lickona, “The Neglected Heart: The Emotional Dangers of Premature Sexual Involvement” (January 2007), 11.
[17]. “Tracking the Hidden Epidemics,” 4.
[18]. Centers for Disease Control, “2006 Sexually Transmitted Diseases Treatment Guidelines” (September 2006).
[19]. “Chlamydia,” fact sheet, CDC.
[20]. F.X. Bosch, et al., “Chlamydia Trachomatis and Invasive Cervical Cancer: A Pooled Analysis of the IARC Multicentric Case-Control,” International Journal of Cancer111:3 (September 1, 2004), 431–439.
[21]. National Institutes of Health, “Workshop Summary: Scientific Evidence on Condom Effectiveness for Sexually Transmitted Disease (STD) Prevention,” 17.
[22]. Ahmed S, et al., “HIV Incidence and Sexually Transmitted Disease Prevalence Associated with Condom Use: A Population Study in Rakai, Uganda,” AIDS 15:16 (2001), 2171–2179; J. Baeten, et al., “Hormonal Contraception and Risk of Sexually Transmitted Disease Acquisition: Results from a Prospective Study,” American Journal of Obstetrics & Gynecology 185:2 (2001), 380–385.