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Chlamydia (“kla-MID-ee-uh”) is a curable sexually transmitted infection (STI), which is caused by bacteria called Chlamydia trachomatis. You can get genital chlamydial infection during oral, vaginal, or anal sexual contact with an infected partner. It can cause serious problems in men and women, such as penile discharge and infertility respectively, as well as in newborn babies of infected mothers.

Chlamydia is one of the most widespread bacterial STIs in the United States. The Centers for Disease Control and Prevention (CDC) estimates that more than 3 million people are infected each year.

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Chlamydia bacteria live in vaginal fluid and in semen. Chlamydia is sometimes called the “silent” disease because you can have it and not know it. Symptoms usually appear within 1 to 3 weeks after being infected. Those who do have symptoms may have an abnormal discharge (mucus or pus) from the vagina or penis or experience pain while urinating. These early symptoms may be very mild.

The infection may move inside your body if it is not treated. Bacteria can infect the cervix, fallopian tubes, and urine canal in women, where they can cause pelvic inflammatory disease (PID). In men the bacteria can cause epidydimitis (inflammation of the reproductive area near the testicles). PID and epidydimitis are two very serious illnesses.

C. trachomatis also can cause inflammation of the rectum and lining of the eye (conjunctivitis or “pink eye”). The bacteria also can infect the throat from oral sexual contact with an infected partner.

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Chlamydia is easily confused with gonorrhea because the symptoms of both diseases are similar and the diseases can occur together, though rarely.

The most reliable ways to find out whether the infection is chlamydia are through laboratory tests.

  • The usual test is for a health care provider to collect a sample of fluid from the vagina or penis and send it to a laboratory that will look for the bacteria.

  • The other test looks for bacteria in a urine sample and does not require a pelvic exam or swabbing of the penis, and results are available within 24 hours.

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If you are infected with C. trachomatis, your health care provider will probably give you a prescription for an antibiotic such as azithromycin (taken for one day only) or doxycycline (taken for 7 days). Or, you might get a prescription for another antibiotic such as erythromycin or ofloxacin.

Health care providers may treat pregnant women with azithromycin or erythromycin, or sometimes, with amoxicillin. Penicillin, which health care providers often use to treat some other STIs, won’t cure chlamydial infections.

If you have chlamydia, you should

  • Take all your medicine, even after symptoms disappear, for the amount of time prescribed

  • Go to your health care provider again if your symptoms do not disappear within 1 to 2 weeks after finishing the medicine

  • Tell your sex partners that you have chlamydia so they can be tested and treated, if necessary

You also should not have sexual intercourse until your treatment is completed and successful.

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The surest way to avoid transmission of STIs is to not have sexual contact or to be in a long-term mutually monogamous relationship with a partner who has been tested and is not infected.

You can reduce your chances of getting chlamydia or giving it to your partner by using male latex condoms correctly every time you have sexual intercourse.

Health experts recommend chlamydia screening annually for all sexually active women 25 years of age and younger. Health care experts also recommend an annual screening test for older women with risk factors for chlamydia (a new sex partner or many sex partners). In addition, all pregnant women should have a screening test for chlamydia.

If you experience genital symptoms like burning while urinating or have a discharge, you should see your health care provider immediately.

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Each year up to 1 million women in the United States develop PID, a serious infection of the reproductive organs. As many as half of all cases of PID may be due to chlamydial infection, and many of these women don’t have symptoms. PID can cause scarring of the fallopian tubes, which can block the tubes and prevent fertilization from taking place. Researchers estimate that 100,000 women each year become infertile because of PID.

In other cases, scarring may interfere with the passage of the fertilized egg to the uterus during pregnancy. When this happens, the egg may attach itself to the fallopian tube. This is called ectopic or tubal pregnancy. This very serious condition results in a miscarriage and can cause death of the mother.

In men, untreated chlamydial infections may lead to pain or swelling in the scrotal area. This is a sign of inflammation of the epididymis. Though complications in men are rare, infection could cause, pain, fever, and sterility.

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A baby who is exposed to C. trachomatis in the birth canal during delivery may develop an eye infection or pneumonia. Symptoms of conjunctivitis, which include discharge and swollen eyelids, usually develop within the first 10 days of life.

Symptoms of pneumonia, including a cough that gets steadily worse and congestion, most often develop within 3 to 6 weeks of birth. Health care providers can treat both conditions successfully with antibiotics. Because of these risks to the newborn, many providers recommend that all pregnant women get tested for chlamydia as part of their prenatal care.

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National Library of Medicine MedlinePlus

Centers for Disease Control and Prevention

CDC National STD and AIDS Hotline

American Social Health Association

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