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.

What is it exactly? A bacterial infection which infects the cervix and can spread to the urethra, fallopian tubes, and ovaries in women. It can cause chronic bladder infections and pelvic inflammatory disease, ectopic pregnancy, and permanent infertility. In men, chlamydia infects the urethra and can spread to the testicles, which can cause male infertility. Accoording 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.

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 intercourse for women, 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 men, of the testicles or fertility problems.

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

Is it treatable? Yes, with antibiotics.

Is it curable? Yes.

Can it effect fertility? In both men and women, left untreated, chlamydia can cause infertility. 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 or anal intercourse and oral sex.