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Illustration by Marta Pucci

Sex

Chlamydia 101

by Nicole Telfer, Science Content Producer
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Top things to know about chlamydia:

  • Chlamydia is often asymptomatic, meaning that many people don’t know they have it
  • Chlamydia symptoms can include pus-like yellow discharge; frequent or painful urination; spotting between periods or after sex; and/or rectal pain, bleeding, or discharge
  • Untreated, it can lead to pelvic inflammatory disease, chronic pelvic pain, ectopic pregnancy, and/or infertility in women and people with female reproductive tracts
  • Antibiotics are used to treat chlamydia infections

What is chlamydia?

Chlamydia is a very common sexually transmitted infection (STI). Chlamydia trachomatis is a type of bacteria which can cause a number of different infections across the body. Chlamydia is most commonly known for infecting body parts related to reproduction (1).

What are chlamydia symptoms?

Chlamydia in women and people with female reproductive organs is often asymptomatic. This means that people often do not experience any discomfort or notice any changes while infected.

Without any symptoms, people may be infected and not know it. Some people may have very mild or vague symptoms after they are infected, which can be confused with a urinary tract infection or vaginal infection (2).

Chlamydia symptoms can include:

  • Pus-like yellow discharge
  • Frequent painful urination
  • Spotting/bleeding between periods or after vaginal intercourse
  • Rectal pain, bleeding, or discharge

What happens if chlamydia goes untreated?

A sexually transmitted infection of chlamydia can cause an infection of the cervix, urethra, and fallopian tubes in people with female reproductive organs (2,3).

As time progresses and an untreated chlamydia infection continues to spread, serious and long-term consequences like pelvic inflammatory disease (PID), ectopic pregnancy, infertility, or chronic pelvic pain may develop in individuals with female reproductive organs. Chlamydia bacteria travel up the reproductive tract from the vagina through the cervix to the uterus, ovaries, and fallopian tubes, causing inflammation and infection. Once inside, the bacteria damage the ovaries and fallopian tubes, and can cause scarring (4). This can have long-term effects including infertility, as scar tissue can block the fallopian tubes, preventing sperm from fertilizing an egg. Ectopic pregnancies (where a pregnancy implants outside of the uterus) are also more common, as a fertilized egg may get stuck in the damaged fallopian tube—this can be life threatening.

Chronic pelvic pain is also a possible long-term consequence of untreated chlamydia infections and is a symptom of PID (5).

In people with male reproductive organs, chlamydia can cause an infection of the urethra and epididymis, the tube that collects and stores sperm from the testicles (1).

How common is chlamydia?

In the United States, chlamydia infection rates are on the rise, making chlamydia the most commonly reported sexually transmitted infection in the country. In 2016, almost 1.6 million cases of chlamydia were reported to the Centers for Disease Control (CDC) (1).

In the U.S., women are about twice as likely to be reported to have chlamydia as men. However, this is likely due to screening practices, since women are often screened during their annual pelvic exams. Men do not generally have similar annual screenings of their reproductive organs.

Since women are more likely to be asymptomatic, the number of people who actually have chlamydia could be even higher. Also, as testing becomes more sensitive and screening becomes more common and available, this trend is expected to continue to rise.

People (both men and women) aged 15 to 25 years old make up almost two thirds of all chlamydia cases reported in 2016 to the CDC (1). More specifically, up to 1 in 20 sexually active young women aged 14-24 could have chlamydia in the US (6).

Outside of the US, chlamydia is also very common. In 2012, the worldwide estimate of chlamydia infections was around 131 million new cases of chlamydia per year (7). This number is close to that of the entire population of Japan.

How does one get chlamydia?

Chlamydia is spread through sexual contact with an infected partner. It can be spread through any type of unprotected sex, including penis in vagina sex, anal sex, and oral sex (3). An eye infection, conjunctivitis, can also be acquired through contact with genital fluids infected with chlamydia.

A person can also be re-infected with chlamydia after having been treated previously. People don’t become immune to chlamydia after they’ve had it once.

How do I prevent chlamydia?

Using condoms every time you have sex can greatly reduce the risk of contracting chlamydia. Condoms should be used not just during ejaculation, but before any genital or sexual contact starts. If you are having oral-vaginal sex, use a dental dam to stay protected.

Ask a partner whether they’ve been tested recently for STIs before starting sexual contact. If a partner has sex with multiple people, ask about their STI status and encourage them to also get tested. Limiting the number of sexual partners you are exposed to will also decrease your risk of contracting chlamydia.

For people with female reproductive organs, a yearly gynecologic visit is recommended, even for those in a monogamous longterm relationship. People who are sexually active should always be screened for chlamydia. The screening can easily be performed—on a urine specimen, or as part of a pelvic exam.

How is chlamydia treated?

Chlamydia can be treated with antibiotics to kill the bacteria. After getting a diagnosis, it is recommended that any partner that you have had sexual contact with in the last 60 days, and/or your last sexual partner, be tested.

It is possible to transmit chlamydia even while being treated with antibiotics. Stay away from sexual contact until 7 days after completion of the full course of antibiotic medication—even if symptoms have already gone away. Three months after treatment, you should get re-tested for chlamydia (2).

Special cases: chlamydia in infants, and HIV

Newborn infants are also at risk for chlamydial infections if their mother has an untreated infection at the time of delivery. Newborn infants can contract chlamydia trachomatis as they travel through the birth canal and develop eye infections or pneumonia (1). For this reason, chlamydia testing should be routine during pregnancy.

Having an STI, like chlamydia, can also increase your chances of contracting HIV if you are exposed it to it, or spreading HIV if you are already infected (8,9). If you think you have chlamydia, or any STI, it is important for you to seek help immediately from your healthcare provider or an STI clinic. Many clinics provide free or low-cost STI testing. This will all help keep you, your sexual partners, and your community healthy.

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Article was originally published on June 11, 2018.

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