The STI Files: Chlamydia

Stat: Chlamydia is the most common sexually transmitted bacterial infection⁠ in the United States, with about 3 million new cases reported annually. Chlamydia ("cla-mid-ee-ah") is so common in young women that, by age 30, 50% of sexually active⁠ women have evidence that they have had chlamydia⁠ at some time during their lives.

The highest age-specific chlamydia rates have occurred among women ages 15 to 19 and 20 to 24, and among U.S. males, were also highest in 15- to 19-year-old and 20- to 24-year-old men (CDC, 2009).

What is it exactly? A bacterial infection which infects the cervix⁠ initially and can spread to the urethra⁠ , fallopian tubes⁠ , and ovaries⁠ in people who have a vulva⁠ . It can cause chronic bladder infections and pelvic inflammatory disease, ectopic pregnancy⁠ , and permanent infertility. Chlamydia can also infect the throat when acquired through oral sex⁠ .

For people who have a penis⁠ , chlamydia infects the urethra and can spread to the testicles, which can cause male infertility. According to Planned Parenthood, chlamydia can also lead to Reiter's syndrome, especially in young men, which involves eye infections, urethritis, and arthritis. One in three men who develop Reiter's syndrome become permanently disabled.

About how many people have it? About 3 million cases are reported each year in the United States alone. From 1989 through 2008, reported chlamydia rates rose from 102.5 to 401.3 cases per 100,000 population in the United States (CDC, 2009). That increase is partly attributed, to improved screening and reporting. However, in young people ages 15-24, the reported rate of Chlamydia is four times that of the general population, so it is known to be a particularly widespread infection for those in their teens and twenties.

How is it spread? Through vaginal or anal intercourse⁠ , oral sex, during childbirth, and in rare cases, from hand to eye and other nonsexual contact.

What are its symptoms? In most cases, chlamydia shows no symptoms. When symptoms are present, they may include: pain or burning while urinating, vaginal bleeding, painful vaginal intercourse⁠ for people who have a vulva, spotting between periods or after or during intercourse⁠ , stomach or abdominal pain or nausea, fevers, swelling or pain of the rectum⁠ or cervix, or in people who have a penis, of the testicles or fertility⁠ problems. People who have a penis may also experience discharge⁠ from the penis.

How is it diagnosed? By a urine or tissue sample from the genitals⁠ or throat.

Is it treatable? Yes, with antibiotics. It is also usually very easy to treat. However, ALL partners MUST be treated when one partner⁠ tests positive. If you get Chlamydia and get treated, but your partner does not, and you keep having sex⁠ (particularly unprotected), you can wind up passing⁠ the infection back and forth again and again, something which happens frequently in partnerships where everyone isn't getting tested or partners are still going without condoms even after a recent Chlamydia infection. It's really important to abstain from any unprotected sex until all partners are completely finished with treatment, and found, via a new test afterward, to be clear of the infection.

Is it curable? Yes, but you can get it again.

Can it affect fertility? In people of all genders, left untreated, chlamydia can cause infertility when left untreated or when someone waits a long time to get treatment, which often happens when people don't get tested regularly to know they need treatment. Chlamydia can also cause (via PID⁠ ) ectopic pregnancy, and in infants, chlamydia can cause pneumonia, eye infections or blindness.

Can it cause death? Not in and of itself.

How can we protect against it? By using condoms every time for vaginal intercourse, anal intercourse and/or oral sex, getting tested regularly and making sure sexual⁠ partners are also being tested regularly.

Want to find out about other STIs?

Similar articles and advice

  • Finn Black

About one in five people in the United States over age 12 — approximately 45 million individuals — are infected with HSV-II, the virus that causes genital herpes. Around 50-80 percent of the adult population has oral herpes, which most people contract through nonsexual contact in childhood.